ANNALS MISSOURI I < < 4/> z < VOLUME 74 1987 z o < S lu I The Annals, published quarterly, contains papers, primarily in systematic botany, contributed from the Missouri Botanical Garden, St. Louis. Papers origi- nating outside the Garden will also be accepted. Authors should write the Editor for information concerning arrangements for publishing in the Annals. Editorial Committee Georgf K. Rogers, Editor Missouri Botanical Garden Marshall R. Crosby Missouri Botanical Garden Gehrit Davidse Missouri Botanical Garden John D. Dwyer Missouri Botanical Garden & St. Louis University Peter Goldblatt Missouri Botanical Garden Henk van der Werff Missouri Botanical Garden Colophon This volume of the Annals of the Missouri Botanical Garden has been set in APS Times Roman. The text is set in 9 point type while the figure legends and literature cited sections are set in 8 point type. 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Editorial Committee George K. Rogers and Nancy R. Morin Coeditors (this issue), Missouri Botanical Garden Janice Wilson Editorial Assistant, Missouri Botanical Ga rden Marshall R. Crosby Missouri Botanical Garden Gerrit Davidse Missouri Botanical Garden John D. Dwyer Missouri Botanical Garden & Saint Louis University Peter Goldblatt Missouri Botanical Garden Henk van der Werff Missouri Botanical Garden subscrip Box scription price is $75 per volume U.S., $80 Canada and Mexico, $90 all other countries. Airmail deliv- ery charge, $35 per volume. Four issues per vol- ume The Annals of the Missouri Botanical Garden (ISSN 0026-6493) is published quarterly by the Missouri Botanical Garden, 2345 Tower Grove Av- enue, St. Louis, MO 63110. Second class postage paid at St. Louis, MO and additional mailing offices. Postmaster: Send address changes to Department Eleven, P.O. Box 299, St. Louis, MO 63166. Missouri Botanical Garden 1987 Volume 74 Number 1987 Annals of the Missouri Botanical Garden SYSTEMATIC EMBRYOLOGY OF THE ANISOPHYLLEACEAE 1 HiROSHI TOBE^ AND PeTER H. RAVEN^ Abstract An embryologicai study of Anisophylleaceae, which comprise Anisophyllea, Combretocarpus, Poga, and Polygonanthus, and which have traditionally most often been referred as a tribe or subfamily to Rhizophoraceae, is presented as a contribution to the clarification of the systematic position of the family and the evolutionary interrelationships of its constituent genera. The gametic chromosome number of Co mbretocarpus is reported as ^ = 8, that of the other three genera as « = 7. Embryologically Anisophylleaceae are diversified and show differences from genus to genus, but they are clearly distinct from Rhizophoraceae in having their combination of consistent character states, including persistent nucellar tissue at least until early stages of seed development, thin two cell-layered inner integument (Poga and Polygonanthus), and exalbuminous seeds. In contrast to Rhizophoraceae, Anisophylleaceae agree almost completely with Myrtales in their embryologicai features of the order. Embryologicai evidence therefore supports the recognition of Anisophylleaceae as a distinct family and, with support from other lines of evidence, suggests a Myrtalean affinity for the family. Proposed assignments of Anisophylleaceae to Resales or to Comales are not supported. An analysis of similarities in character states in the four genera suggests that the ancestral Anisophylleaceae diverged into two main branches: one leading to Anisophyllea and Combretocarpus, and the other leading to Poga and Polygonanthus. Combretocarpus, with which Anisophyllea shares a few synapomorphies, is most specialized within the family in having many apomorphies. In contrast, Poga and Polygonanthus share many plesio- morphies, most of which are also common to Anisophyllea. Anisophylleaceae, as defined here, consists of referred P(9/v^OA2art//2M5 to Euphorbiaceae(Ducke, four genera and 34 species, Anisophyllea (30 spp.), 1932, 1933; Kuhlmann, 1 940), Olacaceae (Croi- Combretocarpus{\ sp.), Poga{l sp.), sind Polygo- zat, 1939), Saxifragaceae (Baehni & Dansereau, nanthus (2 spp.) (Airy Shaw, 1973; Cronquist, 1939), or to its own family, Polygonanthaceae 1981, 1983). In contrast with the stable assign- (Croizat, 1 943). Despite these, there is little doubt, ment of three other genera, various authors have on the basis of morphological and wood anatom- * Supported by grants to the junior author from the U.S. National Science Foundation and in part by the Grant-in-Aid Scientific Research to the senior author from the Ministry of Education, Science and Culture, Japan. We are grateful to J. O. Ariwaodo, Peter S. Ashton, Paul Chai, Steven R. Hill, Adrian M. Juncosa, C. Kalkman, Duncan W. Thomas, and Mohd Shah Bin Mohd Noor for their collection and arrangement of the excellent material used in this study, and to Rolf Dahlgren, L. A. S. Johnson, Adrian Juncosa, and Richard Keating for their useful comments regarding this manuscript. r ^ Biological Laboratory, Yoshida College, Kyoto University, Kyoto 606, Japan. ^ Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166. Ann. Missouri Bot. Gard. 74: 1-26. 1987, 2 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Table 1. Studied taxa and collections. Taxa (Jack.) Baill. Anisophyllca sp. Combretocarpus rotun- datus (Miq.) Dans. Poga oleosa Pierre Collections Anisophyllca disticha Singapore. Bukit Timah Nature Reserve. Sidek Bin Kiah & Tan Yam Leong s.n. in 1984, no voucher. Singapore. Botanic Garden, Singapore. Sidek Bin Kiah s.n. in 1984, no voucher; Mohd Shah s.n. in 1984, no voucher. Malaysia. Maxwell Hill, Perak. B. C. Stone 15403, (KLU, MO). Brunei. A. M. Juncosa s.n. in 1981, no voucher. Cameroon. D. W. Thomas 3494, (MO). Malaysia. Kuching, Sarawak. P. Chai s.n. in 1981, 1983, and 1985, no voucher. Brunei. A. M. Juncosa s.n. in 1983, no voucher. Cameroon. Korup Natl. Park. D. W. Thomas 2273, (MO). Nigeria. Awi, Akamkpa. J. O. Ariwaodo s.n. in 1983, (FHI 99607). Polygonanthus amazoni- Brazil. Along the Rio Paca, Amazonas. /. Zarucchi 3138, 3184, (US) cus Ducke ical evidence, that Polygonanthus fits well in An- lationships between Anisophylleaceae and Rhi- isophylleaceae, together with the three other gen- zophoraceae, placed Anisophylleaceae in Cor- own Rhizophorales (Myrtiflorae era that have traditionally been placed there (see nales Kuhlmann, 1944; Fires & Rodrigues, 1971; Van order Vliet, 1976). Of the four genera of this family, gren & Thome, 1984). Anisophyllca is relatively widely distributed in In the light of these diverse opinions, we have tropical Africa and Asia, also occurring in trop- attempted to determine whether Anisophylle- ical South America; Combretocarpus \^ restricted aceae are actually closely related to Rhizophora- to West Malaysia, Poga to tropical West Africa; ceae sensu stricto or not, or whether they might and Po/j/^ona/^/Z/w^ to the Amazon Basin of Bra- even be grouped together as one family. If the zil (Fires & Rodrigues, 197 1). two groups are not closely related, what are their The relationships of Anisophylleaceae have respective affinities? been controversial. A traditional view, and the Anisophylleaceae have been studied to a very one most widely accepted, is that Anisophylle- limited extent, particularly regarding their ana- aceae have close affinities with Rhizophoraceae, tomical characteristics. Their wood anatomy, and they often have been considered a tribe or however, has been studied relatively intensively subfamily within a broadly conceived Rhizopho- (Marco, 1935; Geh & Keng, 1974; Van Vliet, raceae (Bentham & Hooker, 1865; Baillon, 1877; 1976). Based on a comparison of the wood anat- Schimper, 1893; Melchior, 1964; Fires & Ro- omy of the two groups, Van Vliet (1976) sup- drigues, 1971; Geh & Keng, 1974; Van Vliet, ported a broad definition of Rhizophoraceae in- 1976; Takhtajan, 1980). Even when they have eluding Anisophylleaceae. In contrast, Behnke been treated as a distinct family, Anisophylle- (1984), basing his conclusions on the features of aceae have generally been considered closely re- tube plastids, suggested lated to Rhizophoraceae (Ridley, 1922; Comer, leaccae were quite distinct from Rhizophoraceae 1940). The resulting family, Rhizophoraceae sensu stricto. He found that both Anisophyllca sensu lato, has traditionally been placed in the and Combretocarpus have S-type plastids (con- Myrtales (Bentham & Hooker, 1865; Schimper, taining starch grains only) in contrast to the F-type 1893; Melchior, 1964; Takhtajan, 1980), but plastids (containing protein) that are character- Thome (1983) placed Rhizophoraceae (com- istic of Rhizophoraceae sensu stricto. Another posed of two subfamilies: Rhizophoroideae and interesting distinction between the two groups, Anisophylleoideae) in the Comales. which has been known for some time, is that all Recently, however, Cronquist (1981, 1983) four genera of Anisophylleaceae are aluminum concluded that Anisophylleaceae were not closely accumulators; whereas the genera of Rhizopho- related to Rhizophoraceae and assigned them to raceae sensu stricto are not (Chenery, 1948; Resales (Rosidae) and Rhizophoraceae sensu Miller stricto to its own order, Rhizophorales (Rosidae). logical information has been extremely useful in Dahlgren (1983), who also denied any close re- suggesting relationships at this level (see Tobe & 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 3 Raven, 1983), almost no information is available affin techniques, were embedded in a JB-4 plastic on Anisophylleaceae. The only published data and stained with 0.1% Toluidine Blue, on ovule morphology (of^'Anisophylleia zeylan- In order to count the number of cells in mature ica"") is that of Karsten (1891) nearly 100 years pollen, we attempted to use safranin-staining of ago; however, most of these observations seem the grains (Tobe & Raven, 1984). We failed to to be incorrect, as we shall discuss subsequently, obtain any staining of the pollen nuclei, however, Vaughan (1970) described the mature seed coat probably because a thick exine hinders the infil- structure of Po^^, providing a drawing; Geh and tration of dye. Consequently, we counted the Keng (1974) reported on the endosperm in the number of cells in the pollen using microtome- seeds of Anisophyllea and Combretocarpus. Ex- sectioned pollen grains. The expressions we have cept for these fragments of information, appar- used for the frequency of different shapes of mi- ently nothing has been reported about the em- crospore tetrads follow those of Schmid (1982). bryological features of Anisophylleaceae. In this paper, we present an overall study of the embryology of Anisophylleaceae, which is intended to provide information bearing on their relationships and systematic position. We have Observations ANISOPHYLLEA R. BR. The embryological characteristics were basi- sUxdi^d Anisophyllea w^<^ Combretocarpus m dc- cally the same in the two species studied, one tail, and Poga and Polygonanthus to a lesser de- from Africa and one from Asia. The features gree. Important features have been noted for all reported in the following descriptions were found genera and are presented here. Materials and Methods to be common to both species, unless particular comments are given. Anther and microspores. The anther is tetra- All four genera, Anisophyllea, Combretocar- sporangiate. The wall prior to maturation com- pus, Poga, znd Polygonanthus, were investigated prises basically five cell layers: an epidermis, an in this study. The species we studied are listed endothecium, two middle layers, and a tapetum in Table 1 together with their voucher infor- (Fig. 1); the wall formation therefore conforms in all stages of to be the Basic type (Davis, 1966: 1 0). The anther fruits development were collected and fixed in FAA (5 wall, however, often has only one middle layer, formalin; 5 parts glacial which shares a histogenetic origin with the ta- 90 parts 70% ethanol); however, female buds of petum. The tapetum is glandular (Fig. 2). At one Poga oleosa and fruits of Polygonanthus ama- point in their development, the cells of the ta- zonicus were not available. Herbarium material petum become 2-nucleate, but subsequently the of Anisophyllea znd Combretocarpus v^?i%siud\^d two nuclei fuse with each other. During matu- to supplement our observations of fruits and ration, the middle layer(s) degenerate and the epidermal cells are stretched tangentially while seeds. Preparations of microtome sections for obser- the cells of the endothecium become more or less vation were made following standard paraffin enlarged (Fig. 2). Eventually, the endothecium through develops fibrous thickenings. Although the epi- butyl alcohol series, the samples were embedded dermis persists, it is often collapsed on the en- in Paraplast with 56-58°C mp. Flower buds of dothecium (Fig. 3). Anther dehiscence takes place of Poga oleosa by longitudinal slits (Fig. 3). The connective tis- Anisophyllea disticha and fruits of Poga oleosa were too hard to be sectioned without being soft- sue between the two microsporangia of each the- ened initially. Therefore, after these structures ca is completely disorganized before an anther were trimmed to expose their tissues, the embed- dehisces (Fig. 3). ded samples attached to blocks were soaked in Meiosis in a microspore mother cell is accom- a mixture of a 10 : 3 : 90 glycerol : 10% Aerosol panied by simultaneous cytokinesis, and the re- Tumer 20-25 1977) for at least sultant microspore tetrads, on the basis of 50 len sectioned. Se- selected tetrads (of Anisophyllea disticha), are rial sections 6-10 /xm thick were stained with "usually" (92%) tetrahedral, "very occasionally*' Heidenhain's hematoxylin, safranin, and fast- (6%) decussate, and "rarely" (2%) isobilateral. green FCF and were mounted in Entellan. Ma- The pollen grains are two-celled at the time of ture seed coats of Anisophyllea sp. {D. W. Thom- shedding (Fig. 4). as 3494, MO) and Poga oleosa, which were too Chromosomes. Since pollen mother cells be- thick and hard to be sectioned by standard par- tween the telophase of meiosis I and the meta- 4 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figures 1-5. Anisophyllea. — l, 2, 4, 5. A. disticha. — 3. A. sp. (D. W, Thomas 3494, MO). — I. Transverse section (TS) of a young anther showing the five cell-layered wall structure. Bar = 10 /xm. — 2. TS of an older anther with degenerating middle layers (arrow). Bar = 10 mhi. — 3. TS of a developed anther. Its wall consists of the fibrous endothecium and the epidermis. Bar = 50 mhi.— 4. Two-celled mature pollen at the time of shedding. Arrows indicate nuclei of the two cells. Bar = 10 ^m. — 5. Chromosomes of a pollen mother cell at a stage between telophase I and metaphase IL n = 1. Bar = 10 ^m. ep, epidermis; et, endothecium; ml, middle layer; I, tapetum; mc, microspore mother cell. 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 5 phase of meiosis II were fixed by chance and inner integument and the (only) true integument included in microtome sections, we were able to as the outer integument. count the chromosome number of Anisophyllea A micropyle is always formed by the integu- for the first time: A, disticha has n = 1 (Fig. 5), ment, excepting one very unusual case in which Megagametophyte and nucellus. The ovule the integument did not grow beyond the nucellar is anatropous. A single archesporial cell differ- apex (Fig. 16). In this respect as well, Karsten entiates beneath the apical dermal layer of the (1891) seems to have erred: he considered the nucellus (Fig. 6). The archesporial cell divides persistent, lateral nucellar tissue to be the inner periclinally into two: the upper primary parietal integument, which he concluded did not enclose cell and the lower sporogenous cell (Fig. 7). The the nucellar apex. In fact, Karsten concluded that primary parietal cell divides periclinally, and its a micropyle is not formed in "'Anisophylleia zey- derivatives further divide anticlinally and peri- /an/c^." Referring to Karsten's drawing of ovules clinally, forming parietal tissue with three to five and descriptions, we also mistakenly character- layers above the embryo sac. The sporogenous ized the ovule of Anisophyllea not only as being cell develops into a megaspore mother cell and bitegmic but also as having a nucellar beak (which undergoes meiosis, giving rise to a linear tetrad actually was the well-developed persistent nu- of megaspores. A triad of megaspores may also cellar cap; see Tobe & Raven, 1983). be formed by suppression of the second, mitotic The integument is about five to seven cells division on the micropylar side. In the mega- thick in Anisophyllea disticha (Fig. 15) and about spore tetrad (or triad), the chalazal megaspore four to five cells thick in A. sp. (Fig. 1 7). The functions (Fig. 8). A functional megaspore de- thickness of the integument is not different from velops successively into a 2- (Fig. 9), 4- (Fig. 10), one part of ovule to another, and therefore the and 8-nucleate embryo sac (Fig. 1 1). Thus the cross section of the ovule is nearly circular (Fig. mode of the embryo sac formation is of the Po- 17). A raphe bundle ramifies oblique-laterally lygonum type. The synergids are slightly hooked toward the chalazal end (Fig. 18). Therefore in (Fig. 12). The three antipodal cells are ephem- cross section the ovule or fruit has four to five eral, degenerating before fertilization. The two vascular bundles at the peripheral part of the polar nuclei fuse into a single central nucleus, integument of testa (Fig. 19). which is positioned near the egg apparatus (Fig. Throughout the development of the ovule or 13). Consequently an organized mature embryo fruit, the integument or seed coat is thickened sac has only five nuclei or cells: an egg cell, two by secondary multiplication. However, the in- synergids, and two polar nuclei (as a single cen- nermostcell layer never differentiates toward the tral nucleus; Figs. 12, 13). During megasporogenesis and megagameto- so-called endothelium. Fertilization, endosperm, and embryo. De- genesis, apical epidermal cells of the nucellus di- spite their multiovular condition in Aniso- vide periclinally, and their daughter cells also phyllea (usually four and rarely three ovules per repeat periclinal divisions. As a result, a four to ovary), fruits were always one-seeded. Fertiliza- six cell-layered nucellar cap is formed above the tion is porogamous. Endosperm formation is of embryo sac (Fig. 14); Karsten (1891) also illus- the Nuclear type (Fig. 20). Because of incom- trated such a nucellar growth in ''Anisophylleia pleteness of our fruit sample, we could not con- zeylanica,"" The nucellar cap and the other nu- firm whether or not wall formation takes place cellar tissue, both of which enclose the embryo in free endosperm nuclei. Hand-sectioned ma- sac, persist into younger stages of fruit devel- ture seeds of the two species we studied lacked opment (Figs. 11, 14, 17). There is no case in endosperm (Fig. 21). Concerning the presence of which the nucellar tissue degenerates before fer- endosperm in seeds, Hou (1958) described that tilization so that the embryo sac directly borders in Anisophyllea disticha seeds consist of a solid on the integument. body, of which the main part is formed by a Integument. The ovule has a single integu- thick, hardalbumen.Geh and Keng( 1974) stated ment (Figs. 7, 15), although Karsten (1891) de- that in Anisophyllea disticha, the entire undiffer- scribed the ovule of '*' A nisophylleia zeylanica »» entiated embryo is embedded in endosperm; as having two integuments. Judging from the consequently, they characterized the seed of Ani- drawing he published, it seems very probable sophylleae {Anisophyllea and Combretocarpus) that Karsten misunderstood a persistent, lateral as albuminous. Based on results of our obser- nucellar tissue surrounding the embryo sac as the vations, however, it seems that what Hou thought 6 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 FiGUREs6-14. Anisophyllea. — 6,7, 9-13. A. disticha.-S. A. sp.(/). W. Thomas3494, MO).— 6. Longitudinal section (LS) of an ovular primordium with the 1-celled archesporium. Bar = 10 Mm. — 7. LS of a young ovule with the primary parietal cell. Bar = 10 /xm. — 8. LS of a young ovule with the functional megaspore. Arrows above the functional megaspore indicate three degenerating megaspores. Bar = 10 /ini.— 9. LS of an ovule at the 2-nucleate embryo sac stage. Bar = 10 Mm— 10. LS of an older ovule at the 4-nucleate embryo sac stage. One of the two nuclei at the micropylar side appears in the next section. Bar = 10 Mm.— 11. LS of a nearly 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 7 to be the thick, hard albumen was actually the two nuclei in a tapetal cell later are fused with embryo itself, and that the seed that Geh and each other. Thus the mature anther wall is com- Keng observed was too young to confirm the posed of the persistent but somewhat collapsed endosperm condition. epidermis and the fibrous endothecium (Fig. 26). Although we did not pursue the whole process By the time of anther dehiscence, the connective of embryogenesis either, the development of tissue between two microsporangia of each teca proembryos and embryos seems to proceed nor- degenerates completely. After dehiscence by lon- mally (Fig. 20). In embryos of the two species gitudinal slits, the anther wall is remarkably re- we studied, which were dissected from mature flexed (Fig. 27). fruits, we could not observe differentiation of the Meiosis in the microspore mother cells is ac- cotyledons. Geh and Keng (1974), however, re- companied by simultaneous cytokinesis. The ported two protuberances on the apical part of shape of the resultant tetrads, on the basis of the the embryo in Anisophyllea disticha, which they examination of 50 selected tetrads, is "usually" interpreted as two cotyledons. We conclude that (78%) tetrahedral, "occasionally" (14%) decus- the cotyledons ofv^A^/^op/z^^/Z^a either develop in- sate, and "very occasionally" (8%) isobilateral. completely or are essentially absent in Aniso- The pollen grains are two-celled at the time of phyllea. No hypostase is differentiated after fer- shedding (Fig. 28). tilization. Chromosomes. Pollen mother cells at the Mature seed and seed coat. The mature seed metaphase of meiosis I happened to be fixed and is narrowly cylindrical, 13.0-13.5 mm long and appeared in microtome sections. On the basis of 3.8-4.0 mm thick in Anisophyllea disticha, those sections, we observed the chromosomes of whereas it is ovoid or elliptical in outline, 13.0- Combretocarpus for the first time and deter- 13.8 mm long and 6.0-6.4 mm thick in A. sp. mined n = % (Fig. 29). Size differences seem to (Fig. 2 1). In the young seed, the seed coat appears be present among those eight chromosomes. to be constructed of a thick, massive tissue, with Megagametophyte and nucellus. The ovule COMBRETOCARPUS HOOK F. the outer epidermis specialized and tanniferous is anatropous and crassinucellate. The archespo- (Fig. 22). In the mature seed, the seed coat is rium is nearly always 1 -celled (Fig. 30). A multi- formed both of a conspicuous outer epidermis cellular archesporium may very rarely differen- and a multiple inner layer about 25-30 cells thick tiate— an ovule or young fruit containing twin (Fig. 23). The cells of the outer epidermis are embryo sacs was very rarely observed (Fig. 38). thick-walled and cuboid, whereas those of the The archesporial cell divides periclinally into two: underlying multiple inner layer are also thick- the upper primary parietal cell and the lower walled but extremely stretched tangentially. sporogcnous cell. The primary parietal cell may or may not divide further periclinally; if it does so, a two cell-layered parietal tissue is formed. Anther and microspores. The anther is tetra- The sporogenous cell develops into a megaspore sporangiate. The wall prior to maturation com- mother cell (Fig. 31). After enlarging in volume, prises five cell layers: an epidermis, endotheci- the megaspore mother cell undergoes meiosis. um, two middle layers, and a tapetum (Fig. 24). After meiosis I, however, the subsequent mitosis Wall formation conforms to the Basic type. Dur- in each megaspore of the dyad is not accom- ing maturation, the cells of the epidermis are panied by cytokinesis. As a result, both the mi- somewhat enlarged and become tanniferous; the cropylar and the chalazal megaspore of the dyad cells of the endothecium are also enlarged; the become 2-nucleate (Fig. 32). The chalazal mega- middle layers degenerate (Fig. 25). The tapetum spore is functional. Then, while the micropylar is glandular, and its cells become 2-nucleate. The megaspore degenerates, the two nuclei in the mature ovule at the 8-nucleate embryo sac stage. Of the eight nuclei, two polar nuclei are fused into a single central nucleus, and three antipodal cells are degenerating. Bar = 50 ^m.— 12, 13. Two serial LSs of a part of the mature ovule showing the egg apparatus and the central nucleus. Bars = 10 ^m. — 14. Same as Figure 1 1, but at a lower magnification. Note that the nucellar tissue is persistent and that no cell layer of the integument shows differentiation into an endothelium. Bar = 50 ^m. arc, archesporial cell; p, primary parietal cell; s, sporogenous cell; fc, functional megaspore; n, nucleus of the embryo sac; eg, egg cell; ega, egg apparatus; en, central nucleus; ant, antipodal cell; sy, synergid; nuc, nucellar tissue; in, integument; cp, nucellar cap. 8 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figures 15-23. Anisophyllea.- 15, 18-20, 22. A. disticha.-Xd, 17, 21, 23. A. sp. {D. W. Thomas 3494, MO).— 15. Longitudinal section (LS) of a young ovule. Note that the ovule is unitegmic. Bar = 50 mhi.— 16. LS of an unusual mature ovule lacking a micropyle. Bar = 50 /im.— 17. Transverse section (TS) of a mature ovule. Bar = 50 /xm.— 18. LS of a mature ovule tangentially cut through a raphe showing the ramification of a raphe bundle. Bar = 100 ^m.— 19. TS of a young seed. Note that the thick seed coat contains several vascular bundles at the peripheral part. Bar = 1 mm. — 20. LS of a young seed containing a proembryo and free endosperm 1987] TORE & RAVEN-ANISOPHYLLEACEAE 9 functional chalazal megaspore separate from each proembryo (Fig. 40) and at the peripheral region other: one moves toward the micropylar end, of the embryo sac (Fig. 43). Because of incom- while the other moves toward the chalazal end pleteness of our fruit sample, we could not ob- (Fig. 33). Each nucleus divides successively to serve to what degree an amount of endosperm form a 4- and an 8-nucleate sac (Fig. 34). Thus increases later. The mature seeds lack endosperm the embryo sac formation conforms to the bispor- (Figs. 41, 42). We did not investigate embryo- ic Allium type. The synergids are slightly hooked, genesis in detail but can state, on the basis of our and the antipodals are ephemeral, disappearing observations of a few microtome-sectioned before fertilization. Two polar nuclei do not fuse proembryos, that it proceeds normally (Fig. 40), with each other until fertilization takes place; Within the mature fruit of Combretocarpus, they are positioned near the egg apparatus. A the embryo is elongate and nearly circular in mature embryo sac just before fertilization is cross section (Figs. 41, 42). The embryo is di- composed of five nuclei or cells: an egg cell, two cotyledonous with two small cotyledons and a synergids, and two polar nuclei. Embryo sacs characteristically accumulate an abundance of starch grains (Fig. 35). The starch fertilization, grains, which begin to accumulate from the long hypocotyl (Fig. 41). The hypostase is not differentiated even after Mature seed and seed coat. The mature seed 2-nucleate embryo sac stage, are most abundant is linear, 9.5-10.4 mm long and 1.2-1.3 mm in the 8-nucleate embryo sac stage but disappear thick; it contains several vascular bundles in the after fertilization. raphe (Fig. 42), which are derived by ramifica- During megasporogenesis and megagamelo- tion from a raphe bundle. These bundles are re- genesis, the nucellar tissue does not show any stricted to the raphe, never entering the integu- particular differentiation and persists at least un- ment or testa. til the earliest fruit stages (Figs. 36, 38). Apical In the young seed, the seed coat is composed dermal cells of the nucellus do divide periclinally of a tanniferous outer epidermis and a multiple (Fig. 37), and their daughter cells also repeat peri- inner layer, which degenerates (Fig. 43). Even- clinal divisions, thus forming a nucellar cap four tually, in the mature seed, the seed coat com- to six cell layers thick above the embryo sac (Fig. prises only the outer epidermis, which is formed 36). of pigmented, cuboid cells (Fig. 44) POGA PIERRE Anther and microspores. The anther is tetra- Integument. The ovule is unitegmic (Figs. 3 1 , 36). The growing integument is about four or five cells thick (Figs. 36; see also Fig. 38). No differ- ence in thickness exists between the different parts sporangiate. The wall prior to maturation com- ofthe ovule. Therefore, except for the raphe, the prises five cell layers: an epidermis, endotheci- cross section of ovule is nearly circular (Fig. 38). um, two middle layers, and a tapetum (Fig. 45). The integument is not vascularized. Neither sec- Wall formation conforms to the Basic type. Dur- ondary multiplication of the integument nor dif- ing maturation, cells of the epidermis as well as ferentiation of the innermost cell layer into a so- of the endothecium enlarge, while the middle called endothelium occur. layers degenerate (Fig. 46), The tapetum is glan- The integument elongates beyond the nucellar dular, and its cells become 2-nucleate (Fig. 46). apex and forms a micropyle (Fig. 36). The two nuclei in a tapetal cell are not fused with Fertilization, endosperm, and embryo. The each other. The mature anther wall is composed fruits are always one-seeded. Fertilization is po- of the persistent epidermis and the endothecium. rogamous. After fertilization, the fruit elongates The epidermis is tanniferous, and the endothe- remarkably (Fig, 39), Endosperm formation is of cium develops fibrous thickenings (Fig. 47). The the Nuclear type (Fig. 40). In the early stages, anther dehisces by longitudinal slits. By the time free endosperm nuclei are located around the of dehiscence, the connective tissue between two nuclei. Bar = 20 ^m. — 21. Longitudinal hand-section of a mature seed. Note that the mature seed is exalbuminous. Bar = 5 mm. — 22. LS of a young seed showing a thick seed coat. Bar = 200 ^m. — 23. LS of a mature seed coat that is formed by both the multiple inner layer and the conspicuous outer epidermis. Bar = 40 /im. in, integument; nuc, nucellar tissue; rb, raphe bundle; b, vascular bundle; pern, proembryo; fe, free endosperm nucleus; em, embryo; sc, seed coat; epi, epidermis of seed coat; inl, multiple inner layer. 10 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figures 24-29. Combretocarptis rotundatiis.—24. Transverse section (TS) of a young anther showing the five cell-layered wall structure. Bar = 10 ^m. — 25. TS of an older anther with degenerating middle layers. Bar = 10 MiTi. — 26. TS of an anther at the time of dehiscence. Its wall comprises the fibrous endothecium and the epidermis. Bar reflexed. Bar = 27. TS of an older anther than that shown in Figure 26. The anther wall is remarkably — 29. Chromosomes ^SO/xm.- 50 Mm. — 28. Two-celled mature pollen at the time of shedding. Bar = 8. Bar 10 Mm of pollen mother cell at metaphase L n tapetum; mc, microspore mother cell. 2 ^m. ep, epidermis; et, endothecium; ml, middle layer; t, 1987] TORE & RAVEN -ANISOPHYLLEACEAE 11 microsporangia of each theca degenerates com- pletely. In the young seed, the seed coat is composed only of a thick testa and lacks a tegmen. It seems Meiosis in the microspore mother cell is ac- that, during the process of seed development, the companied by simultaneous cytokinesis. The inner integument or tegmen is crushed, while the shape of the resultant tetrads, on the basis of the outer integument or testa increases in thickness examination of 50 selected tetrads are "usually'' by secondary multiplication. Within the young (86%) tetrahedral, "occasionally" (12%) decus- testa, a differentiation into a multiple outer layer sate, and "rarely'" (2%) isobilateral. The pollen and a multiple inner layer can be observed (Fig. grains are 2-celled at the time of shedding (Fig. 57). The multiple outer layer is about 8 cells thick 48). and has cells that are more or less enlarged. In Chromosomes. Using serially sectioned pol- contrast, the multiple inner layer is 7-10 cells len mother cells that were fixed at the later pro- thick, with the cells stretched tangentially (Fig, phase of meiosis I, we observed the chromo- 57). The structure of the mature seed coat ba- somes of Poga for the first time and determined sically does not differ from that of the young seed the chromosome number n = 7 (Figs. 49-51). coat. In the mature seed coat, however, the walls Nucellus and integuments. Although female of the constituent cells are thickened, and the flowers were not available, we confirmed by us- multiple inner layer occupies nearly one-third of ing mature ovules and very young fruits that the the whole thickness of the testa, with the multiple nucellar tissue enclosing the embryo sac persists outer layer occupying the remaining two-thirds at least until the early stages of fruit development (Fig. 58). Because our microtome sections of the (Figs. 52, 54). No hypostase is differentiated even seed coat were not very good, we could not ex- after fertilization. amine the details of cell structure. Vaughan The ovule is bitegmic, i.e., possessing the outer (1970), however, gave a drawing of the anatom- and the inner integument (Fig, 52), The outer ical structure of the testa, which consists of an integument is originally about four or five cells inner layer that is about 12 cells thick and an thick, and the inner integument two cells thick outer layer about six or seven cells thick. Refer- (Fig. 53). The cells of the outer epidermis of the ring to Vaughan (1970), Comer (1976) described outer integument, which later become those of the outer epidermis of the multiple outer layer the outermost layer of the exotesta, are conspic- as composed of cuboid cells with slightly thick- uously enlarged into cuboid cells. The raphe bun- ened, lignified walls, and the other cells of the die ramifies and vascularizes the outer integu- multiple outer layer as thin-walled. ment. In a cross section of a young fruit, six to eight vascular bundles in addition to several raphe bundles are observed in the testa (Fig. 54). The mature seed coat structure of Poga, which is bitegmic, seems comparable with that of An- isophyllea, which is unitegmic. In both genera. The micropyle is formed by both integuments the mature seed coat contains a similar (probably (Fig. 52). Endosperm and embryo. We identical) multiple inner layer, which is charac- teristically composed of tangentially stretched serve either the mode of endosperm formation cells with thick walls. The only evident difference or embryogenesis. But we can say at least that between the mature seed coat structure of Poga the mature seed completely lacks endosperm and that of y^m^op/^j^/Zea lies in thickness of the (Figs. 55, 56) as Vaughan (1970) described, and outer layer, i.e., about six or seven cells thick in that the embryo does not have cotyledons. Con- Poga (see Vaughan, 1 970) and one cell thick (out- cemmg the cotyledons, Vaughan (1970) men- er epidermis only) in Anisophyllea. In other tioned that they are fused. However, judging from words, the seed coat of Anisophyllea, like that of the resemblance in exomorphology of the em- Poga, may also be constructed principally of the bryo with Anisophyllea. it seems that Poga also "testa" (or "outer integument"), which of course lacks cotyledons from the beginning. Mature fruits is not differentiated in the single integument of Anisophyllea, Therefore the seed of unitegmic ways one-seeded. The mature seed is 20.0-22,5 Anisophyllea and even of unitegmic Combreto- mm long and 12.0-13.5 mm thick, is ovoid and carpus (with a mature seed coat consisting only slightly suppressed toward the raphe-antiraphe ofthe outer epidermis) may be regarded as testal, direction, and has a thick, dark brown seed coat and the seed of bitegmic Poga can also be defined (Figs. 55, 56). in this way. 12 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figures 30-38. Combretocarpus rotundatus, --30. Longitudinal section (LS) of an ovule with the I-celled archesporium. Bar = 10 mhi. — 31. LS of a young ovule with the primary parietal cell and the megaspore mother cell. Note that the ovule has only a single integument. Bar = 10 ^m. — 32. LS of a young ovule with the megaspore dyad. Note that each megaspore has two nuclei. Bar = 10 Mm. — 3. LS of an ovule at the 2-nucleate embryo sac stage. Bar = 10 ^m. — 34. LS of a nearly mature ovule at the 8-nucleate embryo sac stage. Bar = 10 /xni. — 35. 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 13 POLYGONANTHUS DUCKE 68; compare with Fig. 33). The accumulation of Anther and microspores. The anther is basi- '^^'"^^ ^'^^"^ ^" *^^ ^^^'^^ ^^^' ^^^^^ ^^ ^h^^' cally tetrasporangiate. The microsporogenous ^^t^^^^ic of C^m^r^'/oc^r/?^^, does not occur in tissue, however, is occasionally transversely di- P^lygonanthus amazonicus. The antipodal cells vided by a septum composed of tapetal cells (Fig are probably ephemeral, because they are absent 59). Although we could not determine the modes ^" ^^^ organized mature embryo sacs (Fig. 69) of anther wall formation, the wall prior to mat- The nucellar tissue enclosing the embryo sac uration comprises five cell layers: an epidermis, ^^ Persistent until at least the stage of fertilization endothecium, two middle layers, and a tapetum. ^^'^^' ^^^^ Periclinal divisions occur in the apical During maturation, the middle layers degener- dermal cells of the nucellus. Therefore the nu- ate, while the cells of both the epidermis and the ^^^^^^ ^^P ^^ P^bably formed by derivatives of endothecium become enlarged (Fig. 59). The ta- ^^^ ^9^c^\ dermal cells. petum is glandular, and its cells become 2-nu- Inleguments. The ovule is bitegmic, i.e., it cleate before degeneration (Fig. 60). The two nu- ^^^ ^^^^ ^" ^^^^^ ^"^ ^^ '^^^^^ integument (Fig. clei in a tapetal cell do not fuse with each other. ^^^' ^he outer integument is initially about five Eventually the mature anther wall is composed ^^"^ ^^'""^^ ^""^ '^^^^ becomes seven to nine or of a persistent epidermis, whose cells are some- ""^"^ ^^"' ^^'""^ because of secondary multipli- what collapsed in places, and a fibrous endothe- ^^^^^^ ^^'g- ^^^^ "^^^ ^^^^^ mtegument, m con- cium (Fig. 61). The connective tissue between trast, is two cells thick (Fig. 67). In the later stages, two microsporangia of each theca degenerates ^^^ ^^"^^ integument becomes very much less completely before the anthers dehisce. conspicuous, while the outer integument in- Meiosis in the microspore mother cells is ac- ^''^^^^^ '" thickness (Fig. 69). Although we could companied by simultaneous cytokinesis. The not observe any stages of the development of the pollen grains are 2-celled at the time of shedding ^^^^ ^^^^^ '^ ^^^^^ ^^^ unhkely that the inner (Fig. 62). integument or tegmen contributes to its structure Chromosomes. Using serially sectioned mi- ^^^^ mature. The raphe bundle ramifies crospore mother cells that were fixed at the late throughout the outer integument, which is there- prophase of meiosis I, the chromosomes of Po- ^^^^ vascularized. In cross section, seven or eight lygonanthus were observed for the first time, bundles in addition to several raphe bundles are Throughout, at examination and reconfirmation observed (Fig. 70). in many cells, we determined the chromosome number of P, amazonicus SiS n = 7 (Figs. 63-65). Megagametophyte and nucellus. Although our observations are fragmentary, we were able to observe some aspects of the process of mega- The micropyle is formed by both integuments (Fig. 69). Discussion Our own results on the embryology and chro- sporogenesis and megagametogenesis in Polygo- mosome numbers of Anisophylleaceae, together nanthus. The ovule is anatropous and crassinu- with some data on ovule and seed morphology cellate. At least one parietal cell is cut off above published earlier (Karsten, 1891; Vaughan, 1970; the megaspore mother cell (Figs. 66, 67). Al- Geh & Keng, 1974), are presented in Table 2. though the mode of embryo sac formation was On this basis, we summarize the embryological not determined, the 2-nucleate embryo sac of features of Anisophylleaceae as follows. Polygonanthus amazonicus differs in aspect from Anther tetrasporangiate, but occasionally that of Combretocarpus rotundatus (which de- polysporangiate because of insertion of tapetal velops a bisporic Allium type embryo sac) (Fig. septa (Polygonanthus); anther wall with five cell Polarized view of the same as that shown in Figure 34, showing a conspicuous accumulation of starch grains in the embryo sac. Bar = 10 ^m. — 36. LS of a mature ovule with an organized embryo sac. Note that the nucellar tissue is persistent. Bar = 50 jum. — 37. LS of a young ovule nearly at the megaspore dyad stage showing periclinal divisions occurring in apical epidermal cells of the nucellus. Bar = 10 /im. — 38. Transverse section of a young seed with twin embryo sacs. Bar = 50 ^m. arc, archesporial cell; p, primary parietal cell; mc, megaspore mother cell; in, integument; n, nucleus of the embryo sac; sy, synergid; pn, polar nucleus; ant, antipodal cell; nuc, nucellar tissue; pd, periclinal cell division; sc, seed coat; es, embryo sac. 14 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 .J.-.^ i iA I ^ \ ^ \ \ cot . X t r ^ w I S ■*-^ s '^ * i I t ■* / ! I r % ®. «'' \v/: * I 4 - '/ V . • ( i » Figures 39-44. Combretocarpus rotundatus. — 39. Longitudinal section (LS) of a remarkably elongated young fruit. Bar 500 ium.— 40. LS of a proembryo with free endosperm nuclei surrounding it. Bar = LS of a mature seed with a cotyledonous embryo. Note that the mature seed is exalbuminous. Bar = = 500Mm.-43. LSof 50Mni.-41. = 1 mm.— 42. Transverse section of a mature seed with several vascular bundles at the raphe. Bar = a young seed coat. Bar = 10 /im.— 44. LS of a mature seed coat. Bar = 10 Mm. pern, proembryo; fe, free endosperm nucellus; cot, cotyledon; em, embryo; sc, seed coat; rb, raphe bundle. layers, its formation of the Basic type; anther ephemeral; tapetum glandular, its cells 2-nu- epidermis persistent, consisting of more or less cleate; the two nuclei in each tapetal cell even- collapsed cells; endothecium persistent and de- tually fused in Anisophyllea and Combretocar- veloping fibrous thickenings; middle layers pus, but not in Poga and Polygonanthus. 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 15 ®- ® K I Figures 45-5 1 . Poga oleosa. —45. Transverse section (TS) of a young anther showing the wall structure with five cell layers. Bar = 10 /im. — 46. TS of an older anther with degenerating middle layers (arrow). Bar = 10 Mm.— 47. TS of a nearly mature anther. Its wall consists of the fibrous endothecium and the epidermis. Bar = 100 fxn\.— 48. Two-celled mature pollen at the time of shedding. Arrows indicate nuclei of the two cells. Bar = 10 Mni— 49-51. Three serial sections of pollen mother cell at the late prophase I showing chromosomes of n = 7. Seven chromosomes are numbered 1 to 7. Bars =10 ^m. ep, epidermis; et. endothecium; ml, middle layer; t, tapetum. Cytokinesis in the microspore mother cells si- Gametic chromosome number a? = 8 in Com- multaneous; microspore tetrads tetrahedral, de- bretocarpus, n = 7 in Anisophyllea, Poga, and cussate, or isobilateral; pollen grains 2-celled Polygonanthus. when shed. Ovule anatropous and crassinucellate; arche- 16 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figures 52-58. Poga oleosa. — 52. Longitudinal section (LS) of a mature ovule. Note that the ovule is bitegmic and has a persistent nucellar tissue. Bar =100 /im. — 53. Transverse section (TS) of a mature ovule showing the inner integument, with two cell layers, and the outer integument, with four cell layers. Bar = 10 Mni. — 54. TS of a young seed showing the vascularized seed coat. Bar = seed. Note that the mature seed is exalbuminous. Bar 500 /im. = 5 mm. 55. Longitudinal hand-section of the mature 56. Transverse hand-section of the mature seed. Bar = 5 mm. — 57. TS of a young seed coat. Note that there is no tegmen and that the testa is differentiating into the multiple inner layer and the multiple outer layer. Bar = 100 juni. — 58. LS of a mature seed coat. Bar = 100 ^m. ii, inner integument; oi, outer integument; es, embryo sac; nuc, nucellar tissue; rb, raphe bundle; b. vascular bundle; sc, seed coat; em, embryo; inl, multiple inner layer; oul, multiple outer layer. 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 17 Ci « k ^'^V>V^? Ai Figures 59-65. Polygonanthus amazonicus.^ 59. Longitudinal section of a developed anther. Arrow indi- cates the tapetal septum dividing a microsporangium. Bar = 50 /im.— 60. Transverse section of a young anther. Bar = 10 ^m. — 61. TS of a mature anther at the time of dehiscence. Its wall consists of the fibrous endothecium and the epidermis. Bar = 50 mhi. — 62. Two-celled mature pollen at the time of shedding. Arrows indicate nuclei of the two cells. Bar = chromosomes of n endothecium. = 10 ^ni. — 63-65. Three serial sections of pollen mother cell at late prophase I showing 7. Seven chromosomes are numbered 1 to 7. Bars = 10 ^m. t, tapetum; ep, epidermis; et, 18 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figures 66-70. Polygonanthus amazonicus. ovule is bitegmic. Bar = 50 Mm— 67. Same as Xh (LS)o shown that the inner integument is two cells thick. Bar = 20 mhi. — 68. LS of an ovule at the 2-nucleate embryo sac stage. Bar = 10 /im. — 69. LS of a mature ovule. Note that the nucellar tissue is persistent. Bar = 50 mhi. — 70. Transverse section of a young ovule showing that the outer integument has vascular bundles, ii, inner integument; oi, outer integument; p, primary parietal cell; mc, megaspore mother cell; n, nucleus of the embryo sac; es, embryo sac; nuc, nucellar tissue; rb, raphe bundle; b, vascular bundle. sporium 1 -celled, cutting off a primary parietal nucellar cells dividing periclinally, forming a nu- cell; embryo sac formation of the Polygonum cellar cap, chalaza without a hypostase. type {Anisophyllea) or the Allium type (Combre- Ovule unitegmic (Anisophyllea and Combre- tocarpus)\ synergids slightly hooked; antipodals tocarpus) or h\\tgm\c{Poga?indPolygonanthiis)\ ephemeral; polar nuclei fused before fertilization in bitegmic ovules, the inner integument two cells {Anisophyllea) or not fused (Combretocarpus). thick and the outer integument thicker; outer Nucellar tissue not degenerating at least until the integument vascularized due to ramification of early stages of seed development; apical dermal raphe bundles, but not vascularized in Combre- 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 19 tocarpus] micropyle formed by either the one Gynotroches, Juncosa (1984a, 1984b) described integument or both integuments, depending on the inner integument of Bruguiera exaristata as whether one or two integuments are present. initially being about 10 cells thick and that of Fertilization porogamous; endosperm forma- Cassipourea elliptica as being about five to eight tion of the Nuclear type; seed exalbuminous; cells thick. In addition, a specialization of the mode of embryogenesis not determined; embryo innermost cell layer of the inner integument into (potentially) dicotyledonous with a long hypo- an endothelium has been reported in some in- cotyl, having either small cotyledons (Combre- land genera of Rhizophoraceae, including Car- tocarpus) or rudimentary and/or no cotyledons allia (Karsten, 1891), Gynotroches (Mauritzon, (Anisophyllea and Poga), Seed coat testal (Poga) 1939), and Cassipourea {Juncosa, 1984a). Anen- or logically testal (Anisophyllea and Combreto- dothelium is never formed in Anisophylleaceae. carpus); mature seed coat formed by the outer Thirdly, the mature seed is exalbuminous in epidermis alone {Combretocarpus), both the out- Anisophylleaceae, but albuminous in Rhizopho- er epidermis and the multiple inner layer {Ani- raceae. The presence of abundant endosperm in sophylled), or both the multiple outer layer and mature seeds has been reported for Rhizophora the multiple inner layer {Poga), Relationships with Rhizophoraceae Although, as shown in Table 2, some of the (Cook, 1907; Carey, 1934; Juncosa, 1982), Ceri- ops (Carey, 1934), and Cassipourea (Juncosa, 1984a). Some critical differences in embryo and seed embryological features of Anisophylleaceae are coat morphology might also be added for distin- diverse, the family is consistent enough in most guishing Anisophylleaceae from Rhizophoraceae such characteristics to allow a more critical com- (see Comer, 1976). However, studies on those parison with Rhizophoraceae than has hitherto characters in Rhizophoraceae are still too limited been possible. In summary, these two families to allow this. Further studies on the embryology share only a few embryological features. They do of Rhizophoraceae, including embryo and seed agree, for example, in having a crassinucellate, coat morphology, are needed to clarify the dif- bitegmic ovule and the Nuclear type of endo- ferences between this family and Anisophylle- sperm formation; but a combination of these and aceae. To sum up, despite insufficient information on other shared features is widespread among many other unrelated families of the angiosperms as the embryology ofRhizophoraceae, the available well. data indicate that Anisophylleaceae differ sig- In contrast, Anisophylleaceae differ from Rhi- nificantly from them. If Anisophylleaceae were zophoraceae in some important embryological included as a tribe or subfamily, Rhizophoraceae features. First of all, in Anisophylleaceae the nu- sensu lato would be defined very broadly. With cellar tissue persists until at least the early stages the support of exclusive occurrence of the nature of seed development, whereas in Rhizophora- of aluminum accumulation (Chenery, 1948; Ku- ceae the nucellar tissue is ephemeral, disappear- kachka & Miller, 1980); alternate, exstipulate ing completely by the time of fertilization (see leaves; three or four free styles (Geh & Keng, Karsten, 1891, for Rhizophora. Ceriops, Bru- 1974); and S-type sieve-element plastids(Behnke, guiera, and Carallia; Cook, 1907, for Rhizopho- 1984) in Anisophylleaceae, the embryological ra\ Carey, 1934, for Rhizophora; Mauritzon, evidence now available strongly suggests that 1939, for Gynotroches; Juncosa, 1984a, 1984b, Anisophylleaceae and Rhizophoraceae are not for Bruguiera and Cassipourea). Therefore in closely related and warrants regarding Aniso- Rhizophoraceae the embryo sac borders directly phylleaceae as a distinct family. on the inner integument. Secondly, in Anisophylleaceae {Poga and Po- lygonanthus) the inner integument is character- Systematic Position of Anisophylleaceae Cronquist (1 98 1 , 1 983) has proposed assigning istically two cells thick, whereas in Rhizophora- Anisophylleaceae to Rosales. Within Rosales, ceae it is much thicker. Indeed, an inner Anisophylleaceae were referred to the suborder integument with four to eight layers has been Grossularineae, which includes six other families illustrated by Karsten (1891) for 5rw^/>ra, Ceri- (Hydrangeaceae, Columelliaceae, Grossulari- o/?5, and Cara///a, by Carey (1934) for /?/z/zo/7/zo- aceae, Greyiaceae, Bruniaceae, and Alseuosmi- ra, and by Mauritzon (1939) for Bruguiera and aceae). Of these, only Grossulariaceae have been 20 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Table 2. Embryological and chromosomal data of Anisophylleaceae. Character Anisophyllea Anther and microspores: Number of sporan- 4 gia Basic type Anther wall devel- opment Anther epidermis Endothecium Tapetum Number of tapetal nuclei Tapetal nuclear fu- Occur Persistent Fibrous Glandular 2 sion Cytokinesis in Simultaneous meiosis Shape of micro- spore tetrad Mature pollen Chromosomes: Base number Usually lelrahe- dral, very occa- sionally decus- sate, rarely isobilateral 2-celled X 7 Megagametophyte and nucellus: Ovule curvature Nature of nucellus Archesporium Anatropous Crassinucellate 1 -celled Thickness of pari- etal tissue Shape of mega- spore tetrad Functional mega- spore Pattern of embryo sac formation Synergids Antipodal cells Number of nuclei or 5 cells in ma- ture embryo sac Accumulation of starch grains in embryo sac Nucellar tissue Nucellar cap Hypostase Integuments: Number of integu- ments Thickness of integ- uments when bi- tegmic 3-5 cell-layered Linear Chalazal cell Polygonum type Slightly hooked Ephemeral 5 Not occur Persistent Formed Not formed 1 Combretocarpus 4 Basic type Persistent Fibrous Glandular 2 Occur Simultaneous Usually tetrahe- dral, occasional- ly decussate, very occasionally isobilateral 2-celled X 8 Anatropous Crassinucellate Nearly always 1 -celled, very rarely 2-cellcd 1-2 cell-layered Linear Chalazal cell Allium type Slightly hooked Ephemeral 5 Occur Persistent Formed Not formed 1 Poga 4 Basic type Persistent Fibrous Glandular 2 Not occur Simultaneous Usually tetrahe- dral, occasional- ly decussate, rarely isobilater- al 2-celled x= 7 Anatropous Crassinucellate 7 7 ? 9 9 9 « 9 9 Persistent ? Not formed 2 i.i. 2 cell-layered; o.i. 4-5 cell-lay- ered Polygonanthus 4, sporangium occa- sionally divided by tapetal septa Persistent Fibrous Glandular 2 Not occur Simultaneous 2-celled X 7 Anatropous Crassinucellate ? 9 ? ? ? Probably ephemeral 5 Not occur Persistent Probably formed Not formed 2 i.i. 2 cell-layered; o.i. about 5 cell- layered 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 21 Table 2. Continued. Character Anisophyllea Combreiocarpus Poga Polygonanthus Vasculature Micropyle forma- tion Differentiation of endothelium Present Absent Present By the only integu- By the only integu- By both integu- ment Not occur mcnt Not occur ments Not occur Fertilization, endosperm, and embryo: Path of pollen tube Porogamous Endosperm forma- Nuclear type tion Endosperm in ma- Absent ture seed Embryogenesis Embryo in mature seed Size of cotyledons when present Porogamous Nuclear type 9 m 7 Absent Absent 9 9 9 Cotyledonous or not cotyledonous Very small (rudi- Cotyledonous Not cotyledonous Small mentary) Mature seed and seed coat: Shape of seed Size of seed and 1.2-1.3 mm diam. Narrow-cylindrical Linear {A. disticha)\ ovoid or ellipti- cal {A. sp.) 13.0-13.6 mm long and 3.8-4.0 mm diam. {A. disticha); 13.0- 13.8 mm long and 6.0-6.4 mm diam (A. sp.) Tegmen — — Whole thickness of 26-31 cell-layered 1 cell-layer seed coat (SC) Thickness of inner 25-30 cell-layered — tiraphe direction 9.5-10.4 mm long 20.5-22.5 mm long, 12.0-13.5 mm wide Ephemeral 1 7-20 cell-layered 7-10 cell-layered layer of SC Thickness of outer layer of SC 1 cell-layer 1 cell-layer About 10 cell-lay- ered Present By both integu- ments Not occur 9 « 9 9 9 Ovoid and slightly ? suppressed to- ward raphe-an- 9 9 9 9 i.i., inner integument; o.i., outer integument. relatively well studied embryologically, v^^hereas 2-nucleale in Anisophylleaceae, but multinu- the others have been studied little or not at all cleate in Grossulariaceae; the integument is vas- in this respect. Anisophylleaceae differ from all cularized in Anisophylleaceae, but not vascular- Grossularineae in having exalbuminous seeds ized in Grossulariaceae; endosperm formation is (Cronquist, 1981). On the other hand, Aniso- of the Nuclear type in Anisophylleaceae, but of phylleaceae resemble Grossulariaceae (princi- the Cellular or the Helobial type in Grossulari- pally Ribes, from which most data are available) aceae; the tegmen is ephemeral in Anisophylle- in nearly all features of anther and microspore aceae (/^o^<3), but persists in Grossulariaceae; the development; in their anatropous, bitegmic, and seeds are non-arillate in Anisophylleaceae, but crassinucellate ovule; Polygonum-type embryo arillate in Grossulariaceae (see Netolitzky, 1926; sac; ephemeral antipodal cells; inner integument Davis, 1966; Comer, 1976, for data on Gros- with two cell layers (see Davis, 1966; Comer, sulariaceae). Therefore it seems that available 1976; Cronquist, 1981, for data on Grossulari- embryological evidence neither supports nor aceae). However, Anisophylleaceae differ from denies a close relationship between Anisophyl- Grossulariaceae in several embryological fea- leaceae and Grossularineae (Rosales). tures. For example, the tapetal cell is basically In contrast, Dahlgren (1983) placed Aniso- 22 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 phylleaceae in the Comales, which comprise 27 ecologically specialized habitats (Natesh & Rau, families including Hydrangeaceae (and five fam- 1984, review). Study of embryogenesis and or- ilies whose position is uncertain; see also Dahl- ganogenesis in seeds through germination seems gren & Thome, 1984). Of 27 families, nine have to be needed for the elucidation of the ecological either not been studied embryologically, or have significance of such specialized embryos in An- bccn studied only to a very limited degree. Of isophylleaceae. Except for the difference in em- the 18 remaining families, nearly all share a uni- bryo morphology, there seems to be essentially tegmic ovule, ephemeral nucellar tissue, endo- a perfect correspondence in embryological fea- thelium, Cellular type of endosperm formation, and albuminous seed. The Comales thus seem res between Anisophylleaceae and Myrtales. Viewing other reproductive and vegetative to be very well defined by a combination of those character states, Anisophylleaceae lack both the shared embryological features. Anisophylle- intraxylary phloem and the vestured pits, which aceae, which lack any of those characteristic em- are regarded as characteristic features defining bryological features of the Comales (almost cer- Myrtales tainly unitegmic ovule in Anisophyllea and 1984; Dahlgren & Thome, 1984). However, the Combretocarpus), seem clearly distinct from the occurrence of S-type sieve-element plastids in Comalean families and do not belong in that Anisophyllea and Combretocarpus, in contrast with the P-type plastids in Rhizophoraceae, agrees Myrtalean affinities with Myrtales (Behnke, 1982, 1984). Tricolpor- order. We would rather suggest Myrtalean affinities for Anisophylleaceae. Embryologically, Aniso- ate pollen morphology in Anisophylleaceae (as phylleaceae agree almost completely with Myr- well as in Rhizophoraceae) is of the basic type tales, and in fact share the eight ordinal cmbry- found in the Myrtales (Erdtman, 1966; see also ological features (see Tobe& Raven, 1983, 1984): Dahlgren & Thome, 1984). Aluminum accu- 1) anther tapetum glandular, 2) ovule crassinu- mulation characteristic of Anisophylleaceae (un- cellate, 3) inner integument two cells thick, 4) known in Rhizophoraceae) is known to occur in micropyle formed by both integuments, 5) an- Crypteroniaceae and Melastomataceae of Myr- tipodal cells ephemeral, 6) endosperm forma- tion—Nuclear type, 7) seed exalbuminous, and les(Chenery, 1948; Kukachka& Miller, 1980). Thus, considering a considerable number of 8) mature pollen 2-celled. One might point out coincidences (in reproductive anatomy) in con- a fusion of tapetal nuclei (in CowZ)r^/ocar/7W5 and trast with a limited number of differences (in Anisophyllea), formation of the nucellar cap, and wood anatomy), in conjunction with support by testal seed as features distinguishing Anisophyl- sieve-element plastid type, palynology, and alu- Icaccae from Myrtales. However, nuclear fusion minum accumulation, it seems that Anisophyl- in the tapetal cells is undoubtedly a secondary leaceae are closely related to Myrtales. Depend- characteristsic that evolved in two genera of An- ing on how we interpret the lack of intraxylary isophylleaceae. Indeed /*(9^a and fc>/v^(9/7an?/?W5', phloem and vestured pits in Anisophylleaceae, both of which have many primitive features, as it might even be justifiable to place Anisophyl- will be discussed later, have unfused tapetal nu- leaceae in the Myrtales. According to Van Vliet clei. The nucellar cap, which is formed by deriv- and Baas (1984), the combined occurrence of atives of the apical nucellar dermal cells, is com- intraxylary phloem and vestured pits is very re- monly observed in Combrelaceae (Myrtales; stricted in the dicotyledons; in fact, except for Venkateswarlu & Rao, 1 972). A seed coat lacking Myrtales a tegmen is frequent in Melastomataceae (Myr- part of the Gentianales, Thymelaeales, Poly- tales; Corner, 1976). Anisophylleaceae may dif- galales, and Polygonales. Outside these orders, fcr from Myrtales in having embryos with re- either one of these features (but not both) spo- duced or rudimentary cotyledons and a long radically occurs in many different groups of di- rphology cotyledons (see Van Vliet & Baas, 1985: 784, fig. to result in hypogeal germination, which is re- 1). Only a few orders are characterized by con- ported in at least Anisophyllea disticha (Geh & sistent possession of one or both of those two Keng, 1974). The peculiar embryo morphology wood anatomical features. Therefore it does not a specialized seem that the lack of intraxylary phloem and positionof Anisophylleaceae. However, embryos vestured pits in Anisophylleaceae necessarily devoid of cotyledons are recorded in many un- precludes a possibility of close affinity with Myr- related families, a majority of them growing in tales. Based on total evidence now available, we suggest 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 23 would suggest that Anisophylleaceae be placed of character state similarities (i.e., synapomor- near Myrtales. Perhaps Anisophylleaceae rep- phiesor symplesiomorphies). Oftheembryolog- resent one of the groups that diverged from a ical features, the Polygonum type embryo sac common ancestral stock with Myrtales and then formation {Anisophyllea) that is characteristic of spread widely. The position of Anisophylleaceae a majority of the dicotyledons (Davis, 1966) is will be evaluated better as the Rosiflorae or the undoubtedly primitive to the Allium type man- Rosales, which are considered phylogenetically ner (Comb ret ocarpus), and also bitegmy (Poga basic in position with respect to Myrtales, are Q,nd Polygonanthus) is pnmitive to the uniiGgmy understood better embryologically. Interrelationships and Evolution OF the Genera (Anisophyllea and Combretocarpus; Bouman, 1984). Concerning the vasculature of the integument, there is no consensus regarding whether or not Because of many shared embryological fea- the vascularized integument represents an ar- tures, as shown in Table 2, as well as of shared chaic condition. Bouman (1984) suggested that vegetative and some other shared reproductive there seems to be a general relation between the features (see also Geh & Keng, 1974; Van Vliet, size of ovules or seeds and the degree of vascu- 1976), there is no doubt that Anisophyllea, Com- larization. As far as Anisophylleaceae are con- bretocarpus, Poga. and Polygonanthus are mono- cemed, the vascularized integument or testa (Ani- phyletic. Despite the lack of data about several sophyllea, Poga, and Polygonanthus) is probably features in Poga and Polygonanthus, the avail- primitive (symplesiomorphous) compared to the able embryological data are now enough to allow nonvascularized one {Combretocarpus). Com- us to compare all four genera. bretocarpus has multiple vascular bundles in the Of these, Combretocarpus is the most distinct, raphe of the mature seed (see Fig. 42). This vas- It has a gametic chromosome number of « = 8, cular condition in Combretocarpus is probably Allium type embryo sac, nonvascularized integ- derived from the condition seen in the three oth- ument, starch grains in the embryo sac, cotyle- er genera by suppression of vascular extension donous embryo, and thin mature seed coat one into the integument, because Combretocarpus has cell layer thick. In contrast, Anisophyllea, Poga, the thin integument that eventually becomes the and Polygonanthus hawe a chromosome rwxmher one cell-layered seed coat at maturity. In this of X = 7, Polygonum type embryo sac (unknown connection, the thick mature seed coat or testa in Poga and Polygonanthus), vascularized integ- is probably primitive (symplesiomorphous) to ument, no starch grains in the embryo sac, non- the thin, one cell-layered mature seed coat. Com- cotyledonous embryo (unknown in Polygonan- pared with Poga, Anisophyllea lacks a hypo- thus), and thick mature seed coat (unknown in dermal tissue in the thick multiple outer layer of Polygonanthus). Combretocarpus agrees with Poga\ Combretocarpus lacks both the multiple Anisophyllea only in having fused tapetal nuclei inner layer and the hypodermal tissue of the mul- and a unitegmic ovule. On the contrary, Aniso- tiple outer layer. Comer (1976, vol. 1: 57) has phyllea differs from Poga and Polygonanthus in considered the limitation of a multiple mechan- sharing neither bitegmic ovules nor distinct ta- ical tissue (probably like that of Poga) into one petal nuclei as well as in not sharing a multiple cell-layered as one of specialization trends of seed outer layer in the mature seed coat (though un- coat. Following Comer, we may be able to pos- certaxnin Polygonanthus). Polygonanthus diners tulate that the successive or simultaneous re- from Poga only in its occasionally divided mi- duction of the multiple inner layer and the hypo- crosporogenous tissue. Except for this, there is dermal tissue of the multiple outer layer had no essential difference between Poga and Poly- occurred in the seed coat evolution of Aniso- gonanthus, as far as the data available are con- phylleaceae so that only the epidermis was per- cemed. sistenl, as in Combretocarpus. Although we did In order to clarify phylogenetic interrelation- not observe the anatomy of the testa of Polygo- ships of the genera, it seems necessary to evaluate nanthus, it was confirmed that the (outer) integ- each of the characters showing differences be- ument shows a secondary multiplication, a con- tween them. Therefore, as an attempt, we eval- dition that is clearly different from that in uated embryological character states of Aniso- Combretocarpus. Therefore it seems very likely phylleaceae following Eldredge and Cracraft that Polygonanthus would form a mature seed (1980) as regards principles of analyzing methods with as thick a testa as in Poga, 24 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Table 3. Evolutionary trend of karyological and Combretocarpus, a genus that is furnished with some embryological characters in Anisophylleaceae. many advanced and fewer primitive character states as discussed above. In contrast, n 7 is Characters Plesio- morphy Apomorphy 2 1. Number of integu- ments 2. Tapetal nuclei 3. "Outer layer" of the "thick" seed coat (thickness) 4. Chromosome number n = 1 1 Not fused Thick Fused Thin, 1 cell thick n 8 5. Pattern of embryo sac Polygonum Allium type type Present Absent formation 6. "Inner layer" of the mature seed coat 7. Accumulation of starch grains in de- veloping embryo sac 8. Vasculature of integu- Present ments Absent Present Absent shared by Anisophyllea, Poga, and Polygonan- thus. all of which — particularly the latter two retain a combination of primitive character states. Thus it seems likely that n = l'\% the base number of the family, and n = % the derived. The fusion of tapetal nuclei {Anisophyllea and Combretocarpus) certainly seems secondary to the condition in which the two nuclei remain distinct (Poga and Polygonanthus), as discussed earlier. These nuclei also remain distinct in most Myrtales (Tobe & Raven, 1983). The results of our evaluation of these character states are summarized in Table 3. On this basis, we constructed a cladogram illustrating the evo- lutionary interrelationships of the genera (Fig. 71), The cladogram indicates that the proto- Ani- sophylleaceae, a hypothetical ancestor of the family, had nearly all of the embryological fea- tures that are presently retained by Poga and Polygonanthus: a chromosome number of n = The accumulation of starch grains in the de- 7, Polygonum type embryo sac (although ac- veloping embryo sac (Combretocarpus) is known tually uncertain in Poga and Polygonanthus), bi- to occur in many unrelated families of dicoty- tegmy, vascularized integument, thick seed coat ledons (see Davis, 1966). Even within a family, consisting ofa multiple inner layer and a multiple however, their occurrence is in general restricted outer layer, no starch grain accumulation during to certain genera. Therefore the occurrence of megagametogenesis, and non-fused tapetal nu- starch grains seems to have been acquired sec- clei. An ancestral evolutionary line seems to have ondarily by particular groups in many unrelated diverged into two main branches: one leading to families, probably because of the necessity of dif- Combretocarpus and Anisophyllea, and the other ferent metabolic activity during megagameto- leading to Poga and Polygonanthus. In the for- genesis. mer branch, the ovule became unitegmic; tapetal Embryos with moderately developed cotyle- nuclei fusion has been generalized, and the thick- dons are almost universal among dicotyledons ness of the multiple outer layer was reduced into and therefore must be primary. On the contrary, one cell layer (i.e., the outer epidermis); all three because oftheir restricted occurrence (see Natesh characters are synapomorphics common to & Ram, 1984), embryos lacking cotyledons seem Combretocarpus and Anisophyllea, This branch to be secondary in the evolutionary trend. In this further diverged into two branchlets: one leading respect, it might be interpreted that an embryo to Combretocarpus, Sind the other ItadingloAni- with small cotyledons (Combretocarpus) seems sophyllea. In the branchlet leading to Combre- less specialized than that which lacks cotyledons, tocarpus, chromosome base number changed to or at the most has rudimentary ones (Aniso- « = 8; the /i///wm type embryo sac and unitegmy phyllea and Poga). Such differences in the degree were derived; complete reduction of seed coat of size reduction of cotyledons, however, may be tissue except for the outer epidermis (i.e., of both a matter of degree, because it seems to be more a multiple inner layer and the hypodermal tissue fundamentally important that Anisophylleaceae of the original thick seed coat) and reduction of shareaconspicuoushypocotyl, a truly significant integumentary vasculature occurred nearly si- and unusual feature. multaneously; and accumulation of starch grains It may be difficult to determine whether the during megagametogenesis was generalized. With chromosome base number of Anisophylleaceae respect to embryological characteristics, no strik- is n = 7 or 8. Noticeably n = S occurs only in ing change has occurred in the other branchlet 1987] TOBE & RAVEN-ANISOPHYLLEACEAE 25 '^ O o 2fl trees. All of the hummingbird pollinators and E, pallida in Trinidad and Tobago (Fein- may be characterized as long-billed, high-reward singer et al., 1979). trapliners, although some behaved as territori- For this discussion I have adopted a modified alists or even nectar thieves on certain occasions, version oflnouye's (1980) terminology for floral as detailed below, larceny: ''nectar robbers" make a hole or oth- erwise I observed two species of hermit humming- birds (Phaethorninae) pollinating Erythrina: nectar, while "nectar thieves" use the opening Phaethornis guy and P. superciliosus. A third used by legitimate pollinators, but a mismatch hermit species, Glaucis hirsuta, was reported as of the morphologies of flower and animal pre- a pollinator of E, pallida in Trinidad by Fein- eludes pollination. The distinction between nee- singer et al. (1979). The hermits visited princi- tar thieves and robbers is important because rob- pally the smaller understory species of Erythrina bers may damage the ovary or stylar tissue and but rarely were in the forest canopy. Their for- often destroy or remove the entire flower, and aging behavior at understory ^^ry/Zzr/T^a is similar thus may have a much greater effect in reducing to that documented for understory herbs such as the reproductive potential of the plant than do Ileliconia (Stiles, 1975) or shrubs such as Aphe- nectar thieves. Bill lengths (obtained primarily from Ridgway, /^/2^ra (McDade, 1984). The remaining six Erythrina pollinators are 1911) of the hummingbird species observed as non-hermits (Trochilinae); all are long-billed, pollinators and illegitimate visitors to Erythrina high-reward trapliners which forage like hermits, trees are compared in Figure 1. Legitimate pol- but usually in the forest canopy or open areas linators all have bills longer than 28 mm, where- rather than in the understory. Heliomaster con- as nectar thieves and robbers, with one excep- stantii is the principal or sole known pollinator tion, have bills shorter than 22 mm. of at least six Erythrina species in the dry forests on the Pacific slope of Mesoamerica. Its congener POLLINATORS ,,, .t.^ ^jr r i- //. longirostris has been reported from four Er- Nine species of hummingbird were observed ythrina species in more humid lowland forests as legitimate pollinators of the 15 species of Er- on both the Pacific and Caribbean slopes of Me- 1987] NEILL- ERYTHRINA POLLINATION 33 40 SSS CQ ERYTHRINA FLORAL VISITORS: HUMMINGBIRDS Pollinators - TD T3 C n O 0) o Nectar Thieves & Robbers Q n rp n >-o>> Q n 3 CD "D n N 3 n (D CD (D X Q Figure 1. Bill lengths of hummingbird visitors to Erythrina trees, including pollinators and illegitimate visitors. Ph gu = Phaethornis guy\ Ph su ^ Phaethornis superciliosus\ He co = Heliomaster constantii\ He lo = Heliomaster longirostris; Gl hi = Glaucis hirsuta\ Ca he = Campylopterns hemileucurus\ Eu fu = Eugenes fulgens; Ca cu = Campylopterus curvipennis; An pr = Anthrocothorax prevostii; Ph cu = Phaeochroa cuvierii; Am tz = Amazilia tzacatl; Am cy = Amazilia cyanocephala; Hy le = Hylocharis leucotis\ Eu ex = Eupherusa eximia\ He ba = Heliothryx barroti. soamerica, and from E. pallida in Trinidad mid-elevation humid forests sometimes behaved (Feinsingeretal., \91 9). Eugenes fulgens is found as a legitimate pollinator and contacted the re- mostly in the highlands of Mesoamerica above productivepartsof£'r>'^/2A'/w<3hke the other long- 1,500 m. It is the principal pollinator of at least billed trapliners. More frequently, how^ever, An- four highland species of Erythrina, and I also thracothorax was a nectar thief, as described observed it below 1,000 m pollinating E. tux- below. tlana in southern Mexico. Campylopterus hemi- The species of hummingbirds that pollinate leucurus is a bird of wet forests from near sea sect. Erythrina all behave in a similar manner level to 1,800 m and has been observed poUi- when feeding at the flowers. The hummingbird nating three Erythrina species in such habitats. first approaches the inflorescence and hovers to Campylopterus curvipennis was observed as a align its bill precisely with the axis of the first pollinator of two Erythrina species in low- to flower it is to visit (Fig. 2). It inserts its bill at mid-elevation wet forests of southern Mexico. the apex of the flower; at full penetration the Anthracothorax prevostii was the least consis- reproductive parts of the flower always contact tent Erythrina pollinator. This bird of low- to the bird's throat, upper chest, or the base of the 34 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 V P \ * i > I Figures 2-5. Hummingbird pollinators and nectar thieves oi Erythrina sect. Erythrina.^l. Pollinator He- liomaster constantii positioning self to feed at flowers off. lanata\ dry forest near the Pacific coast, Pochutla, Oaxaca, Mexico. Bill is inserted at apex of corolla. — 3. Eugenes fulgens pollinating E. chiapasana\ highland pine-oak forest, Teopisca, Chiapas, Mexico. At full insertion of the bill, pollen is deposited at base of bill or on upper throat. — 4-5. Ilylocharis leucotis, a short-billed nectar thief, approaching and foraging at flowers of E, chiapasana\ same locality as in Figure 3. The bill is inserted into the mouth of the calyx or the sHl of the corolla "pscudotube" to obtain nectar; reproductive parts of the flower are not contacted. bill (Fig. 3). The bird remains hovering at this frF/Z^r/Vzaat different localities inlhe birds' range, position for up to five seconds, then withdraws and more than one pollinator has been recorded and moves to another flower in the inflorescence for many of the Erythrina species. The bird or to another inflorescence. species are quite similar to one another behav- The pollination records summarized in Table iorally and morphologically, and the tree species 2 indicate that there is no species-specific, one- are also quite similar to one another in terms of to-one relationship of Erythrina species and floral morphology, flowering behavior, and nec- hummingbird species. The ecological and geo- tar rewards (the last is discussed below). Ery- graphic distribution of any single Erythrina thrina sect. Erythrina and related groups are ev- species does not correspond precisely with that idcntly adapted to pollination by the high-reward of any pollinator species. Most of the humming- trapliner guild of hummingbirds as a whole. This, birds have been observed at several species of however, is a small subset of all hummingbirds. 1987] ^EILL- ERYTHRINA POLLINATION 35 In Mesoamerica, there are very few additional reproductive parts of the flowers at the apex of hummingbird species with the appropriate mor- the corolla. Unlike the pollinators, thieves fre- phology and behavior for Erythrina tree polli- quently grasp the flowers with their feet when nation, other than the nine species listed in Table feeding and clamber over the inflorescence to 2. (Z)or3^ra /w^ov/aae in the highlands of Costa reach adjacent flowers. They may damage the Rica and Panama may be the only high-reward surface of the corolla somewhat, but they do not trapliner in the region not reported as an Ery- appear to damage the ovary itself. Small nectar thrina pollinator [P. Feinsinger, pers. comm.].) thieves may lack the power to pierce the thick On the local community level, often only a £'ry//zr//7a perianth as do the larger-bodied nectar single high-reward traplining hummingbird is robbers. present so that many populations of Erythrina Most of the hummingbird nectar thieves are are pollinated by a single bird species. In the small species with bills under 21 mm long and lowland dry forests of Pacific Mesoamerica, He- bodies weighing less than 6 g. An exception is liomaster constantii is the only appropriate hum- Anthracothorax prevostii, whose bill length of 28 mingbird present, so it is undoubtedly the sole mm is within the low end of the range of the pollinator of the Erythrina tree species restricted legitimate pollinators and whose body size of 10 to Pacific dry forests g is equivalent to that of the pollinators. A. pre- The hummingbirds are not strict specialists on vostii was occasionally seen visiting Erythrina Erythrina. Well-studied species such as Eugenes flowers in the manner of a true pollinator, but fulgens have been reported visiting a number of more often it behaved as a nectar thief in a man- other plant species. The two Heliomaster species ner similar to the smaller opportunistic birds, may be more specialized as Erythrina foragers than are the other hummingbird genera. During the course of his extensive community-level NECTAR robbers: HUMMINGBIRDS Nectar-robbing hummingbirds have shorter studies of hummingbirds, P. Feinsinger (pers. bills than the pollinators but are larger in body comm.) observed Heliomaster longirostris on size and more powerful than the nectar thieves. Trinidad to feed only at Erythrina pallida and The robbers pierce the calyx or base of the corolla at the apocynaceous vine Mandevilla hirsuta; with their needle-like bills to gain access to Er- while at Monteverde, Costa Rica, Heliomaster ythrina nectar. constantii visited exclusively different species of the same two plant genera. NECTAR THIEVES I observed the large (12 g) hummingbird Phaeochroa cuvierii repeatedly robbing flowers of a roadside Erythrina costaricensis near San Vito de Java in southern Costa Rica. Hovering The nectar thieves oi Erythrina sect. Erythrina beneath or beside the inflorescence, the bird are primarily short-billed, small-bodied, gener- placed the tip of its bill against the fleshy calyx alist hummingbirds. Observed nectar thieves in- and with three or four sharp thrusts punctured dude several species of Amazilia, Hylocharis through the calyx to plunder the nectar. Usually leucotis, Eupherusa eximia, and Chalybura uro- the robber hovered while piercing the flower, but chrysia (Table 1). The short bills of these birds sometimes it perched on the inflorescence. Flow- preclude them from reaching the floral nectar by ers strewn on the ground below the tree had up inserting their bills at the apex of the corolla. to six puncture holes through the underside of Nectar thieves take advantage of the incomplete- the calyx, indicating that Phaeochroa returned to ly sealed tube of the Erythrina corolla. They ap- a single flower several times to drain it of nectar, proach the flower from below (Fig. 4) and, often Most pierced flowers were soon aborted, and with some struggle and manipulation of their some had signs of damage to the ovary caused bills and bodies, slip their bills into the proximal by the robber's bill. On two successive mornings, end of the ventral slit of the pseudotube formed a Phaeochroa repeatedly robbed an E. costari- by the corolla standard, or into the mouth of the censis tree that was also visited at intervals by a calyx (Fig. 5). They are thus able to gain access legitimate pollinator, Heliomaster longirostris. to the nectar within the pseudotube without When on occasion the two birds arrived to feed damaging reproductive tissue. Nectar thief ac- at the tree simultaneously, a territorial fight en- tivity is concentrated at the base of the corolla, sued, and thieves were never observed to contact the In the same region of southern Costa Rica 36 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 where I made the foregoing observations of £". legitimate poIHnators of some Erythrina species costaricensis, Skutch (1971) reported that Heli- such as the widespread E. fusca (sect. Duchas- omaster longirostris pollinated the flowers of Er- saingia) (Morton, 1 979) and the central Mexican ythrina berteroana while Phaeochroa cuvierii and endemic E. oliviae (sect. Olivianac) (Toledo & another short-billed hummer, Heliothryx bar- Hernandez, 1979). These passerine-pollinated rotii, robbed them by piercing the calyx. Ery- Erythrina species are presumed to represent an thrina costaricensis flowers during the Meso- ancestral condition with respect to the hum- american rainy season, August-November, while mingbird-pollinated groups including sect. Ery- E, berteroana flowers during the dry season, late thrina. Orioles and other icterids are known to December to March. The similarity of visitation behave as nectar robbers, in a similar manner to patterns reported for these two species with dif- their behavior at fryr/zr/Vza. at other plant species ferent flowering phenologies in the same region (they are not strictly sympatric) suggests that to- in the Neotropics, including banana {Musa par- adisiaca), which was introduced from the Old gether they support the same pollinators and il- World tropics (Skutch, 1954). In the case of £,>- legitimate visitors in succession for a consider- ythrina. the evolutionary relationship of the ori- able portion of the year. oles' nectar-robbing behavior of the humming- bird-pollinated species to their legitimate NECTAR robbers: PASSERINE BIRDS AND PARROTS pollination of the putatively ancestral passerine- All of the non-hummingbird visitors to Ery- pollinated species remains an open question. Did //ir/Vja sect. £'ry//?r/>?a are nectar robbers and gen- orioles switch to nectar-robbing after having erally destroy the reproductive potential of the evolved nectar-feeding behavior as legitimate flowers they visit. These robbers include passer- pollinators, or was the order reversed? Several species of the honeycreeper family ine birds in the families Icteridae, Coerebidae, and Fringillidae, and the non-passerine parrot (Coerebidae) are nectar robbers of Erythrina family Psittacidae. Icterids and coerebids are le- flowers. I observed the flower-piercer Diglossa gitimate pollinators of some Erythrina species in baritula robbing E. chiapasana in the highlands the Neotropics, but on sect. Erythrina they are of southern Mexico by holding the corolla with strictly parasitic. its specialized hooked upper mandible and pierc- I observed seven species of orioles {Icterus spp.) ing it with its lower mandible to extract the nec- robbing eight species o^ Erythrina in Mexico and tar. Hernandez and Toledo ( 1 979) observed sim- the icterid Cassiculus melanicterus robbing one behavior by the same bird species Erythrina species. Orioles were the most fre- leptorhiza. an herbaceous species of highland quently observed of all robbers and exhibited the central Mexico. most complex behavior to obtain the nectar. Two coerebid bird species, the shining hon- Typically, an oriole would pluck a flower with eycrceper Cyanerpes lucidus and the bananaquit its bill, then hold it against a branch with one Coereba flaveola, were nectar robbers of Ery- foot and jab its bill into the mouth of the calyx thrina tuxtlana. These birds sometimes pierced to reach the nectar. After plundering the flower, calyces in the manner of Diglossa, and at other the oriole would drop it and pluck another. The times slipped their bills into the calyx mouth calyx was split open in this process, and the without puncturing it, in the manner of the short- ground beneath a tree preyed upon by orioles billed hummingbird nectar thieves. Like the ori- would typically be littered with split flowers. This oles, these two honeycreepers that behave as rob- allowed me to count the number of flowers con- bers of hummingbird-pollinated Erythrina sumed daily by the orioles. Sometimes an oriole species are also important legitimate pollinators would impale a flower on a thorn of an Erv//zn>2a of passerine-pollinated Erythrina including E. tree branch to hold it in place while the oriole po^ppp/^/a/ia in Trinidad (Feinsingeretal., 1979) imbibed the nectar; the impaled flowers were left and E. megistophylla in Ecuador (Steiner, 1979). hanging on the branch. The migrant rose-breasted grosbeak Pheucti- Oriole species vary in their degree of special- cus ludovicianus (Fringillidae) nectar-robbed a ization as nectar feeders (Stiles, 1981). Some ev- living fencepost row of hybrid Erythrina berte- idently obtain a high proportion of their caloric roana x E. folkersii and natural populations of requirements from floral nectar, at least during E. folkersii and E. tuxtlana, all on the Atlantic certain seasons of the year. Orioles are important slope of Chiapas, Mexico. Unlike the other pas- 1987] NEILL-- E RYTI I RIN A POLLINATION 37 Table 3. Daily nectar production in flowers of Erythrina sect. Erythrina. Species (Locality) A. First-day flowers E. costaricensis (San Vito de Java) E. globocalyx (Las Nubes) E. chiapasana (El Sumidero) E, goldmanii (El Sumidero) B. Two-day accumulation of nectar E, chiapasana (El Sumidero) E. goldmanii (El Sumidero) Nectar Volume X lA s.d. X Sucrose Equivalence Wt/Vol 36.4 14.7 31.4 ± 19.5 29.6 31.9 12.0 14.6 29% 22.8% 27.3% ± 3.9% 28.9% ± 2.2% 49.8 26.1 27.3 Estimated caloric production of second-day flower (B-A): 52.3 14.1 31.1 Estimated caloric production of second-day flower (B-A): X Calories per Flower 43.8 29.3 33.3 38.2 56.0 22.7 68.1 29.9 N 10 10 12 10 6 9 serine robbers, grosbeaks actually consumed flo- varied relatively little within or among popula- ral tissue as well as nectar. Usually they plucked tions (23%-29%). The calculated mean caloric the flower and either crushed the calyx with their value of the nectar per flower ranged from 29 to bills and dropped the flower or consumed the 43 cal among the sampled populations, with an entire flower. At times grosbeaks merely bit ofT overall mean of 36 cal. the end of the corolla (and pistil), leaving the Ncctarcontinued to accumulate on the second flower attached with the calyx and corolla stump, day of flowering in the bagged flowers off", chia- On several occasions I observed the short-billed pasana and E. goldmanii. The estimated caloric hummingbird yimaz/7/a ^zawa5/^r visit any Other plant, and then only linators. The pollinators, however, constitute a small guild of ''high-reward traplining" hum- mingbirds, about eifiht species in Mesoamerica. hermits for single floral probes. Orioles were frequent visitors to Erythrina goldmanii, and they destroyed an estimated 21% of the flowers daily in the manner described pre- Trochilinae, Predominant among these is the ge- viously. There may have been competition for nus Heliomaster. The pollinators are highly nectar resources between the orioles and the //^- faithful visitors to Erythrina, which provides liomasters, but I never observed any aggressive them with a consistent nectar resource for long interactions between orioles and hummingbirds. periods. The limited caloric value of nectar pro- Species of Erythrina sect. Erythrina are usually duced per tree per day usually precludes the allopatric, being separated by elevation and hab- maintenance of permanent feeding territories at itat; but at El Sumidero two species come into a single tree by the hummingbird visitors. The contact. Erythrina goldmanii inhabits the dry consequent nomadic or "traplining" behavior of lower slopes at about 800 m, and E. chiapasana the hummingbirds and the dispersal patterns of occurs in the moister forest on top of the plateau the pollen they transport among the scattered at 1,100 m. Heliomaster constantii visited Ery- individual £'A7//zr//7a trees may be a critical factor thrina chiapasana just as it did E. goldmanii \ess in the mating systems and genetic structure of than a kilometer away downslope. Both Ery- the low-density Erythrina populations. thrina species and spontaneous hybrids were The pollination system of sect. Erythrina, in found in the intermediate zone, on the upper summary, is a canopy-level analogue of the high- slopes of the El Sumidero escarpment (Neill, in reward traplining pollination systems of Heli- press). The birds evidently do not discriminate co/ua and similar understory plants. In this sense among Erythrina species when the species occur the polHnation system of sect. Erythrina, togelh- together. Heliomaster hummingbirds are cer- er with the other hummingbird-poUinatcd sec- tainly the pollen vectors implicated in interspc- tions of Erythrina trees (sects. Stenotropis, Pseu- cific gene flow between Erythrina species at El do-edules, Gibbosae, and Corallodendra; cf Neill, Sumidero. in press) may be unique. Hummingbird-polli- Erythrina tuxtlana. One final observation nated canopy and subcanopy trees are in them- indicates that traplining hummingbirds will selves uncommon (Stiles, 1978), and I know of sometimes behave as facultative territorialists if no other genus of canopy trees besides Erythrina they are given the opportunity. I observed floral that is adapted to pollination by the traplining visitors to a 20 m tall Erythrina tuxtlana in mid- guild of hummingbirds. elevation wet forest near Malpaso, Chiapas. The To what extent have species of sect. Erythrina treehadabroad-spreadingcrown with 1,400 open and their hummingbird pollinators coevolved? flowers. According to the estimates of nectar pro- To what extent is this a specialized mutualism? duction in other species, this should have been Feinsinger (1983) indicated that a highly spe- enough to support several hummingbirds. In fact, cialized, one-to-one relationship between hermit three hummingbirds of three different species hummingbirds and their food plants is a rare {Heliomaster longirostris, Eugenes fulgens, and occurrence; although they may specialize on a Anthracothorax prevostii) partitioned the crown particular plant species temporarily, most hermit ofthe tree into feeding territories and maintained species forage on a number of different plants, the territories throughout the morning. When not Similarly, most hermit-pollinated plants are ser- feeding, each bird generally perched within its hermits, although territory, and many aggressive interactions en- shorter-billed birds are excluded as pollen vec- sued when one bird crossed into another's ter- tors. If one's definition of coevolution requires ritory. This was the only instance of consistent a high degree of one-to-one species specificity in within-tree territorial thrina population. Ery- such mutualistic interactions, then hermits and hermit-pollinated plants cannot be considered very "tightly coevolved." Feinsinger (1983) con- sidered that "most hermits, hermit-like hum- The flowers of Erythrina sect. Erythrina pro- mingbirds and their food plants exemplify diffuse vide a rich nectar resource that is fed upon by coevolution between two diverse groups of many species of birds besides the legitimate pol- species." Conclusions: Is It Coevolution? 40 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Species of sect. Erythrina vary in the degree of specificity of their association with the hum- mingbird polhnators. Erythrina species of the dry forests of the Pacific slope are pollinated ex- clusively by Heliomaster constantii, so the plant's fitness is directly dependent on the behavior and morphology of a single bird species. The oppor- tunity for the plant to evolve adaptations to spe- cific traits of the bird is clear. Heliomaster con- stantii, however, feeds upon and pollinates a number o{ Erythrina sp>ecies throughout the bird's geographic range, and it also feeds upon and pol- linates at least one other plant genus {Mandevilla\ Feinsinger, pers. comm.). Although there is un- doubtedly a temporary sort of exclusivity in the Erythrina-Heliomaster association in certain ecological communities at certain seasons of the year, the association cannot really be considered an obligate mutualism. The plant-pollinator association is less specific for Erythrina species of highland and wet-forest communities, where several species of traplining hummingbirds often visit and pollinate an in- 310 in D. Futuyma and M. Slalkin (editors), Co- evolution. Sinauer Assoc, Sunderland, Massachu- setts. — & R. K. CoLWELL. 1978. Community orga- nization among neotropical nectar-feeding birds. Amer. Zool. 18: 779-795. , Y. B. LiNHART, L. A. Swarm & J. A. Wolfe. 1 979. Aspects of the pollination biology of three Erythrina species on Trinidad and Tobago. Ann. Missouri Bot. Card. 66: 451-471. GuiLLARMOD, A. J., R. A. JuBB & C. J. Skead. 1979. Field studies of six southern African sp)ecies of Erythrina. Ann. Missouri Bot. Gard. 66: 521-527. Hernandez, H. M. 1982. Female sterility in Ery- thrina montana. Allertonia 3(1): 72-76. & V. M. Toledo. 1979. The role of nectar robbers and pollinators in the reproduction oi Er- ythrina leptorhiza. Ann. Missouri Bot. Gard. 66: 512-520. &^ . 1982. ¥\ord\h\o\o%y o{ Erythrina batolohium and the evolution of pollination sys- tems in American species of the genus. Allertonia 3(1): 78-84. Inouye, D. W. 1980. The terminology of floral lar- ceny. Ecology 61: 1251-1253. Krukoff, B. a. & R. C. Barneby. 1974. A con- spectus of the genus Erythrina, Lloydia 37: 332- 459. dividual tree on a single day. Hummingbirds such Linhart, Y. B. 1973. Ecological and behavioral de- as Eugenes and Campylopterus visit a rather v^ide variety of plants besides Erythrina. Even in these cases, however, such plant-pollinator associa- McDade, L. A. 1984. Systematics and reproductive terminants of pollen dispersal in hummingbird- pollinated Heliconia. Amer. Naturalist 107: 51 1- 523. tions involving high-reward traplining hum- mingbirds are much more exclusive than those biology of the Central American species of the Aphelandra pulcherrima complex (Acanthaceae). 04- involving short-billed generalist hummingbirds j^^^^illen, R. E. & F. L. Carpenter. 1977. Daily and short-corolla plants. Among the species of sect. Erythrina, there is energy costs and body weight in nectarivorous birds. Com. Biochem. Physiol. 56A: 439-441. little differentiation in floral morphology, flow- Morton, E. S. 1979. Effective pollination oi Ery- ering patterns, or morphology and behavior of the pollinators— the pollination system of all thrinafusca by the orchard oriole {Icterus spurius): coevolved behavioral manipulation? Ann. Mis- souri Bot. Gard. 66: 482-489. species is quite similar. Rather, species are dif- Neill, D.A. In press. Experimental studies on species ferentiated by their restriction to distinct climatic and edaphic conditions. This large group of species, as a whole, has evolved a particular set of adaptations to the guild of high-reward trap- lining hummingbirds. relationships in Erythrina (Legummosae: Papilio- noideae). Monogr. Syst. Bot. Missouri Bot. Gard. RioGWAY, R. 1911. The birds of North and Middle America. Bull. U.S. Nat. Mus. 50, part V. Skutch, a. F. 1 954. Life Histories of Central Amer- ican Birds. Cooper Ornithological Club. . 1971. A Naturalist in Costa Rica. Univ. of LrrERATURE Cited BoLTEN, A. B., P. Feinsinger, I. Baker & H. G. Baker. 1980. On the calculation of sugar concentration in flower nectar. Oecologia 41; 301-304. Cruden, W. R. & V. M. Toledo. 1977. Oriole pol- lination of Erythrina hreviflora (Leguminosae): Florida Press, Gainesville Slud, p. La Rica: a tropical wet forest locality. Bull. Am. Mus. Nat. Hist. 121: 49-148. Steiner, K. E. 1979. Passerine pollination of £'ry- thrina megistophylla Diels (Fabaceae). Ann. Mis- souri Bot. Gard. 66; 490-502. evidence for a polytypic view of omithophily. Plant Stiles, F. G. 1975. Ecology, flowering phenology and Syst. Evol. 126: 393-403. Feinsinger, P. 1978. Ecological interactions between plants and birds in a successional tropical com- munity. Ecol. Monogr. 48: 269-287. . 1 983. Coevolution and pollination. Pp. 282- hummingbird pollination of some Costa Rican Heliconia species. Ecology 56: 285-301. — . 1978. Ecological and evolutionary implica- tions of bird pollination. Amer. Zool. 18: 603- 615. 1987] neill-i:rythrina pollination 41 . 1981. Geographical aspects of bird-flower CO- 1,200 m. 8°45'N; 82''55'W. Premontane Rain Forest, evolution, with particular reference to Central roadside. Tree 6 m. 11-12 Sept. 19SI. Neill 5099. America. Ann. Missouri Bot. Gard. 68: 323-351. 8. E. gibbosa Cufodontis. Costa Rica: Alajuela, up- ToLEDO, V. M. 1974. Observations on the relation- per Penas Blancas Valley, below Monteverde Reserve. ship between hummingbirds and Erythrina species. Lloydia 37: 482-487. — 4fe H. M. Hernandez. 1979. Erythrina oliviae: a new case of oriole pollination in Mexico. Ann. Missouri Bot. Gard. 66: 503-5 11. Appendix Locality and Voucher Data for Erythrina Populations Used in Observations of Floral Visitors (Numbers correspond to those listed in Table 1) 1. E, americana Miller. Mexico: Oaxaca, 5 km E of San Pablo Coatlan. 16°12'N; 96°47'W. Elev. 1,450 m. racruz, Los Tuxtlas Biological Station. Elev. 200 m. Disturbed gallery forest with r-a.vod//wm, and cultivated 18''3rN; 95°03'W. Tropical Wet Forest. Understory/ fields. Tree to 20 m, along intermittent stream. 9-10 subcanopy tree to 8 m. 28 Jan. 1983. A. Gentry 32490. Elev, 1,400 m. 10^20'N; 84°45'W. Premontane Rain Forest; edge of pasture. Tree to 4 m. 4-6 Sept. 1981, Neill 5057. 9. E. globocalyx Porsch & Cufodontis. Costa Rica: San Jose, Las Nubes. Elev. 1,700 m. 9'^53'N; 24^00'W. Fencepost row, border of pasture. Tree to 8 m; sporadic along stream. 14 Aug., 25 Sept. \9^\. Neill 5033, 5142. 10. E, goldmanii Standley. Mexico; Chiapas, El Sumidero National Park, Km 7. Elev. 900 m. 16°47'N; 93°06'W. Tropical Dry Forest; secondary, disturbed scrub. Tree 8 m. 25 Feb.-l March 1983. Neill, 5497, 5498. 11. E. folkersii Krukoff & Moldenke. Mexico: Ve- Feb. 1983. Neill 542 L 5424. 2, E. berteroana Urban x E. folkersii Krukoff & Moldenke. Mexico: Chiapas, 3 km S of Palenque. Elev. 100 m. 17°28'N; 92°00'W. Fencepost bordering field. Tree to 8 m. 18 March 1983. Neill 5533. 3. E. berenices Krukoff & Bameby. Mexico: Vera- cruz, Tequila. 19°45'N;97°03'W.Elev. 1,650 m, Coffee plantation; Premontane Wet Forest. Tree to 12 m. 26 Jan. 1983. Neill 5381. 1 2. E. folkersii Krukoff & Moldenke. Mexico: Chia- pas, Palenque Archaeological Site. 17°29'N; 92°01'W. Tropical Wet Forest; forest edge. Tree 5 m. 19 March 1983. Neill 5534. 13. E. lanata Rose. Mexico: Oaxaca, 37 km W of Puerto Escondido. Elev. 20 m. 15°90'N; 97°20'W. Tropical Dry Forest, scrub. Tree 6 m. 13 Feb. 1983. Neill 5430. 14. E. lanata Rose. Mexico: Jalisco, Chamela Bio- 4. £■. chiapasana Krukoff. Mexico: Chiapas, El logical Station. Elev. 250 m. 19°30'N; 105°03'W. Tree Sumidero National Park, Km 14-16. Elev. 1,100 m. 7 m. 13 Jan. 1983. Neill 5329. 16M7'N; 93''06'W. Disturbed Premontane Dry Forest, 1 5. E. pudica Krukoff & Bameby. Mexico: Chiapas, transition to moist mixed Quercus forest. Tree 15 m. Rio de la Venta, Cascada El Aguacero. Elev. 750 m. 2-4, 9, 25 March 1983. Neill 5455, 5458, 5465. 16^46'N; 93°33'W. Tropical Dry Forest, scrub. Tree 6 5. E. chiapasana Krukoff. Mexico: Chiapas, 13 km m. 27, 31 March 1983. Neill 5512. EofTeopisca. Elev. 2,000 m. 16°30'N; 92'^25'W. Pine- Krukoff oak forest. Tree 7 m. 22-23 March 1983. Neill 5445. pas, 25 km N of Ocozocuautla. Elev. 700 m, 16°48'N; 6. E. cochleata Standley. Costa Rica: Heredia, La 93°25'W. Premontane Wet Forest; karsl limestone. Tree Selva Biological Station. Elev. 200 m. I0°24'N; to 20 m. 28 March, 9 April 1983. Neill 5486, 5621. 84°00'W. Tropical Wet Forest. Tree 25 m. 1 5-1 8 Aug., 18-21 Sept. \9U. Neill 5015, 5101. 7. E. costaricensis Michcli. Costa Rica: Puntarenas, San Vito de Java, Las Cruces Botanical Garden. Elev. 17 April 1983. Neill 5642. 17. E. tuxtlana Krukoff & Bameby. Mexico: Ve- racruz, Uxpanapa. Elev. 90 m. 17°irN; 94°39'W. Tropical Wet Forest; karst limestone. Tree 15 m. 16- A COMPARISON OF THE DIVERSITY, DENSITY, AND FORAGING BEHAVIOR OF BEES AND WASPS ON AUSTRALIAN ACACIA 1 Peter Bernhardt^ Abstract Twenty-seven bee taxa and 24 wasp laxa were collected on the open inflorescences and/or extra- floral nectaries of eight Acacia species in Victoria, Australia. Despite this superficial similarity in taxonomic diversity, bees outnumbered wasp foragers by 88% of the combined catch of winged Hymcnoptera. Representatives from five families of bees were recorded, with the short-tongued Halicti- dae and Collelidae comprising the largest unit of native Apoidea on the Acacia species studied. Pollen foraging female bees of the genera Lasioglossum (Halictidae) and Leioproctus (Colletidae) comprised 83% of the combined catch of the two short-tongued families. The number of bee taxa collected on the Acacia species tended to increase from late winter through late autumn. Polylectic foraging bee taxa expanded from mid spring through late summer when the flowering of nectariferous Myrtaceae peaked. There was no correlation between the density and diversity of bees foraging on Acacia species bearing secreting extra-floral nectaries and those species that lacked extra-floral nectar while the inflorescences were blossoming. Representatives of seven families of wasps were collected on the eight Acacia species. No wasps, however, were collected on var. retinodes o{ A. retinodes. Approximately 66% of the wasps collected belonged to the families Sphecidae and Tiphiidae. Wasps repeatedly foraged on extra-floral nectar before foraging on nectarless inflorescences. The density and taxonomic diversity of wasps remained highest on the Acacia species that offered the greatest volume of sucrose-rich, extra- floral nectar (i.e., ^. terminalis). Bees are probably more important pollinators q{ Acacia in southeastern Australia than are wasps. The direct influence of wasps on polyad dispersal appears to be nominal except in those Acacia species bearing functional extra-floral nectaries. Winged Hymcnoptera (bees and wasps) have Knox, 1979; Knox & Kenrick, 1982). Conse- been observed to forage frequently on inflores- quently, bees, wasps, and certain flies easily col- cences of Australian Acacia. In contrast to the lect polyads from the synchronously opening flo- Psyllidae and some Coleoptcra, bees and non- rets in an inflorescence. parasitic wasps are not destructive to the small Female bees are known to collect Acacia poly- flowers that comprise an Acacia head or spike ads to feed to their larvae. Foraging bees remove (Bernhardt, 1982). Instead evidence suggests that polyads from the anthers via thoracic vibration Hymcnoptera are often pollinators of somey4c^- of whole inflorescences (Buchmann, 1983) or by cia species in southeastern Australia (Bernhardt, scraping anthers directly with their forelegs (Vo- 1982; Bernhardt et al., 1984; Knox et al., 1985). gel, 1978), or both (Bernhardt & Walker The flowers of all Australian Acacia examined 1985). Acacia species are usually self-incompat- thus far are nectarless (Bernhardt, 1982; Bern- ible. Seed set tends to occur only when pollina- hardt et al., 1984; Bernhardt & Walker, 1984, 1985; J. Kenrick & G. Beresford, pers. comm.). belonging (Kn The pollen grains, which are fused together to et ah, 1984; Kenrick et al., 1984b) form polyads, are the primary edible reward Capture records of insects foraging on Acacia When the anthers dehisce the eight polyads pres- in southeastern Australia and analyses of their ent in each anther are extruded, or partially ex- suggest truded, from their respective sacs (Kenrick & more important as polyad vectors than are either ^ Research was conducted at the Plant Cell Biology Research Centre of the School of Botany, University of Melbourne under the supervision of R. B. Knox. Funding was provided by the Australian Research Grants Scheme and the Australian Department of Education (CPPER). I thank A. Heisler and the rangers of the National Parks Service, Victoria (Brisbane Ranges, Cape Schanck) for their cooperation. This study would not have been possible without the timely assistance of J. Kenrick, G. Beresford, R. Marginson, P. O'Neal, and T. Hough, J. Walker of the National Museum of Victoria identified Hymcnoptera and sent unidentified wasps to other Australian authorities. I am most grateful for the continuing interest and support of R. B. Knox and D. M. Calder. C. D. Michener provided a most valuable critique of the original manuscript. ^ Department of Biology, Saint Louis University, 3507 Laclede, St. Louis, Missouri 63103. Ann, Missouri Bot. Gard. 74: 42-50. 1987. 1987] BERNHARDT-AUSTRALIAN ACACIA 43 beetle or fly taxa. Calliphorid and syrphid flies transport polyads from Acacia inflorescence to inflorescence without damage, but they may oc- bane Ranges National Park: Dry sclerophyll woodland/shrubland (see Bernhardt & Walk- er, 1984). cur on Acacia inflorescences at lower density and 5) A. paradoxa DC. (syn. A. armata R. Br.). 1 2/ diversity than Hymenoptera (Bernhardt et al., 1984; Knoxet al., 1985). Excluding the rare documentation of pollina- ix/84-31/x/84. Brisbane Ranges National Park: Dry sclerophyll woodland/shrubland (see Bernhardt and Walker, 1984). birds or marsupials (see review by Turner, 6) A. pvcnantha Benth. 1 l/viii/82-16/ix/82. 1982; Knox et al, 1985) the flowering behavior, floral presentation, and polyad presentation of most Acacia species would be expected to favor Brisbane Ranges National Park: Dry sclero- phyll woodland/shrubland (see Bernhardt & Walker, 1984). a system of generaHst entomophily (Bernhardt, 7) A. retinodesw^r, ret i nodes Schdl. 16/1/82-17/ St al., 1984). That is, all insects i/82. Grampians National Park: Montane and 1982; Bernhardt et al., 1984). That is, all insects that forage for polyads have immediate access to the inflorescences of Acacia and could effect deposition of polyads on respective stigmas. valley dry sclerophyll forest/shrubland with adjacent epacrid heaths (see Bernhardt & Walker, 1985). Therefore the purpose of this study was to de- 8) A. retinodes van uncifolia J. Black. 15/xi/81 termine which groups within the Hymenoptera were major vectors of Acacia polyads with suf- ficient fidelity to regularly effect seed set. To ac- complish this end the density and taxonomic di- 5/iii/82. Cape Schanck National Park: Coast- al calcareous dune flora consisting of tall shrubland and invasive, naturalized shrubs and herbs (see Bernhardt et al., 1984). versityofpolyad foragers were compared to their 9) A. terminalis Machr. 18/iii/83-28/iv/83. Er- respective activities on Acacia inflorescences. Materials and Methods Acacia species and study sites. Eight Acacia were selected to determine interspecific and in- traspecific foraging preferences of Hymenoptera. The species of Acacia may be found in flower throughout the year (Kenricketal. 1984a, 1984b; Bernhardt, 1982) with the majority flowering from August through October (Costermans, 1983). Therefore the eight selected species rep- resented the 1 2-month flowering season of the genus but emphasized the period of intensively overlapping floral phenology from the last month of winter (August) until the second month of spring (October). The periods of fieldwork, study sites, and habitats of each Acacia species are list- ed below. Descriptions of floristic alliances fol- low Spccht and colleagues (1979). ica-Moe (south Gippsland) and Boolah Boo- lah State Forest. Moist sclerophyll woodland/ forest with a rain forest element (see Knox et al., 1985). Analysis of Hymenoptera, The foraging be- havior of Hymenoptera was observed and re- corded over the respective periods of fieldwork every day or every other day. Insects were col- lected selectively from 8 a.m. until 2 p.m. as for- aging behavior becomes negligible by mid after- noon. Insects were collected only if they were ob- served foraging on the open inflorescences of Acacia and/or taking nectar from extra-floral nectaries on the leaves or phyllodes of ^. lon- gifolia, A. myrtifolia, A. pycnantha (Bernhardt & Walker, 1984), and A, terminalis (Knox et al., 1985). Foraging is defined here as the active re- moval of polyads from anthers or the probing of 1) /Icac/a fon5'//ecies of Australian Acacia. Int. J. Entomol. 26: 322-330. & 1985. Insect foraging on Acacia retinodes var. retinodes. Int. J. Entomol. 27: 97- 101. — , J. Kenrick & R. B. Knox. 1984. Pollination biology and the breeding system of Acacia reti- nodes (Leguminoseae: Mimosoideae). Ann. Mis- souri Bot. Gard. 71: 17-29. BucHMANN, S. L. 1983. Buzz pollination in angio- sperms. Pp. 73-114 in C. E. Jones & R. J. Little (editors), Handbook of Experimental Pollination Biology. Van Nostrand Rheinhold Inc., New York. CosTERMANS, L. 1983. Native Trees and Shrubs of Southeastern Australia. Rigby Publishers, Austra- lia. Faegri, K. & L. VAN DER PijL. 1979. Principles of Pollination Ecology, 3rd edition. Pergamon, Ox- ford/New York. patibility in Acacia, —a pre- or post zygotic mech- anism? Pp. 146-153 in E. G. Williams it R. B. Knox (editors). Pollination '84. Plant Cell Biology Research Centre, School of Botany, Univ. of Mel- bourne, Australia. , P. Bernhardt, R. Marginson, G. Beresford & R. B. Knox. 1984b. Acacia breeding systems. P. 210 in E. G. Williams 8l R. B. Knox (editors), Pollination '84. Plant Cell Biology Research Centre, School of Botany, Univ. of Melbourne, Australia. Knox, R. B. & J. Kenrick. 1982. Polyad function in relation to the breeding system of Acacia. Pp. 411-418 in D. Mulcahy & E. Ottaviano (editors), Pollen Biology. North Holland Press, Amsterdam. , y P. Bernhardt, R. Marginson, G, Beresford, I. Baker & H. G. Baker. 1985. Ex- tra-floral nectaries as adaptations for bird polli- nation in Acacia terminalis. Amer. J. Bot. 72: 1 1 85- 1196. Macior, L. W. 1968. Bombus (Hymenoptera, Api- dae) queen foraging in relation to vernal pollina- tion in Wisconsin. Ecology 49: 20-25. Michener, C. D. 1965. A classification of the bees of the Australian and South Pacific regions. Bull. Amer. Mus. Natur. Hist. 130: 1-362. . 1974. The Social Behavior ofthe Bees. Belk- nap Press of Harvard Univ., Cambridge, Massa- chusetts. . 1979. Biogeography ofthe bees. Ann. Mis- souri Bot. Gard. 16: 277-347. Ogden, E. C, G. S. Raynor, J. V. Havers, D. M. Lewis & J. H. Haints. 1974. Manual for Sam- pling Airborne Pollen. Hafner, New York. Simpson, B. B., J. L. Neff& A. R. Moldenke. 1977. Pp. 84-107 in B. B. Simpson (editor), Mesquite, Its Biology in Two Desert Scrub Ecosystems. Dowden, Hutchinson & Ross, Inc., Stroudsburg, Pennsylvania. Specht, R. a., E. M. Rae & V. H. Boughton. 1974. Conservation of major plant communities in Aus- tralia and Papua New Guinea. Austral. J. Bot. Suppl. Ser. 7: 1-667. Turner, V. 1982. Non-flying mammal pollination; an opportunity in Australia. Pp. 1 10-121 in E. G. Williams, R. B. Knox, J. H. Gilbert & P. Bernhardt (editors). Pollination '82. Plant Cell Biology Re- search Centre, School of Botany, Univ. of Mel- bourne, Australia. Vogel, S, 1978, Evolutionary shifts from reward to deception in poUen flowers. Pp. 89-96 in A. J, Richards (editor). The Pollination of Flowers by Insects. Linn. See. Symp. No. 6, Academic Press, London. FLOWER LONGEVITY AND PROTANDRY IN TWO SPECIES OF GENTIANA (GENTI ANACE AE) ^ C. J. Webb and Jan Littleton^ Abstract Both Gentiana saxosa and G. serodna are protandrous. When flowers open, pollen is presented extrorsely around the closed stigma for one to six days. As the stigma opens, the stamens curve toward the corolla lobes. The length of the female phase, and therefore reproductive flower life, is determined by pollination, although in both species the corolla may remain fresh for longer than one month. Fresh female-phase flowers close at night and fail to reopen on the day following pollination. After five days in the female phase, flowers reacted less quickly to pollination and seed production was reduced; flowers pollinated on their tenth day of stigma presentation produced no seed although they appeared fresh. Senescence of unpollinated flowers differed between species: in G. saxosa the flowers remained open and gradually deteriorated, but in G. serodna the flowers eventually closed before full senescence. Pollination-induced flower senescence has been demonstrated for a number of other angiosperms, and the usual reactions to pollination are corolla abscission, color change, or wilting. In Gentiana, the closed corolla enfolds the large superior ovary and may serve to protect it from predators as well as prevent further pollinator visits. Pollination-induced flower senescence probably also minimizes flower maintenance costs by ensuring that the flower functions no longer than necessary. One correlate of this phenomenon in hermaphroditic flowers is protandry, which ensures pollen dispatch before flower closure. Floral senescence may be either time-depen- presentation and so may influence or be influ- dent (endogenous) or exogenous (usually polli- enced by the extent and nature of dichogamy nation-induced). However, there have been few (Lloyd & Webb, 1986). detailed investigations of the factors that deter- New Zealand species of Gentiana (in the mine floral senescence, and hence, floral longev- southern group of Philipson, 1972) are protan- ity (Primack, 1 985). Most such studies have con- drous (Thomson, 1881; Simpson & Webb, 1 980; centrated on corolla color changes or other Webb, 1984a). Their large, relatively simple physiological reactions that follow pollination and flowers make them particularly suitable subjects signal senescence (e.g., Arditti et al., 1973; Ar- for experimental studies of flower function. This ditti, 1976;Gottsberger, 1971; Gori, 1983; Strauss paper describes the response of flowers of two & Arditti, 1984; Casper & La Pine, 1984;Halevy, species to pollination and reports the results of 1984), and less attention has been afforded struc- experiments to determine the functional dura- tural changes such as wilting, flower closure, and tion of male and female phases in terms of pollen corolla abscission (Mayak & Halevy, 1980). Most presentation and seed production, of this research is concerned with the proximate determinants of floral longevity rather than the evolution of particular responses (but see Stead & Moore, 1979; Gori, 1983; Casper & La Pine, Materials and Methods The two species of Gentiana selected were those 1984; Devlin & Stephenson, 1984). The paucity that grew best in cultivation. Gentiana saxosa of research on the evolutionary aspect of flower Forster f. grows naturally in coastal sites of south- senescence is somewhat surprising, because pol- em South Island and Stewart Island, New Zea- lination-induced senescence in particular may land; plants were collected from Curio Bay, have important consequences for the pollination Southland. Gentiana serotina Cockayne occurs system and ultimately for the plant's overall re- in grassland in inland central South Island; plants productive strategy. For instance, in hermaph- were collected from Lake Lyndon, Canterbury, rodite flowers pollination-induced flower senes- The plants were grown in clay pots in an insect- cence will limit the duration of pollen and stigma proof cage in greenhouses at Lincoln, Canter- ' We thank I. C. Brown and garden staff at Lincoln, Canterbury, for maintaining the plants in cultivation, J. Miles for assistance with photographs, and P. Brooke for drawing Figures 2 and 3. We are grateful to L. F. Delph-Lively, E. Edgar, and D. G. Lloyd for comments on a draft of the manuscript. ^ Botany Division, Department of Scientific and Industrial Research, Private Bag, Christchurch, New Zealand. Ann, Missouri Box. Gard. 74: 51-57. 1987. 52 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Table 1. Results of conti rolled polhnations to de- lermine self-compatibility in Gentiana saxosa : and G. serotina. % Seeds Pro- Num- Cap- duced ber of sules per Mow- Pro- Cap- Treatment ers duced sule G. saxosa Cross- 10 10 94.2 incompletely), or (c) the number of days until the corolla withered and turned brown (for flow- ers that never closed). When capsules were ma- ture they were harvested and seed production scored. At Lake Lyndon, 10 fresh, unbagged, female- phase flowers of G. serotina were cross-pollinat- ed by hand, and ten were left unpollinated. These flowers were examined the following day. Results pollinated Self- 10 10 94.2 Flower U phenology, and pollina- G. serotina 10 5 5 57.9 5 5 67.6 tion. Both Gentiana saxosa and G. serotina are perennial herbs with a central leafy rosette and stout taproot. The flowers are on annual, leafy, lateral flowering branches that bear from one to eight flowers in G. serotina and one to 30 or more in G. saxosa. The corolla is deeply 5-lobcd, white with translucent stripes on the lobes and upper tube (Fig. 1), and greenish-yellow toward the base of the tube. The five stamens are attached to the corolla tube; the anthers are purple and the pollen bury. Field observations were made at Lake Lyn- is cream to brownish-yellow. Nectar is produced don. between the bases of the filaments near the base To test for self-incompatibility and autogamy of the tube. The central ovary contains an av- 10 flowers in G. saxosa and five flowers in G. erage of 29 ovules in G. saxosa and 47 in G. pollinated Unpollinated Cross- pollinated Self- pollinated Unpollinated 5 serotina were assigned to each of three treat- (Webb ments: self- and cross-pollination by hand, and defined style; the stigma is 2-lobed, distinctly tagged When in- papillate, and dry. les In the field, G. saxosa blooms in summer and matured, they were harvested and good seeds autumn (January to May), and G. serotina from and aborted seeds or undeveloped ovules were late summer to autumn (February to May). Un- der ereenhouse conditions G. saxosa reached peak counted The duration of male and female phases was flowering in December and G. serotina in March. determined for individual tagged and stigma presentation were observed daily un- The flowers arc sweetly scented and visited on fine davs bv a ranee of insects. At Lake Lvndon, tilpetals withered and turned brown. Of 61 flow- G. serotina was most frequently visited by syr- ers of G. saxosa observed daily, five were cross- phid flies and solitary bees {Lasioglossum sor- pollinated on each of the first to tenth days of didum). During anthesis, flowers opened com- their female phase, and 1 1 left unpollinated. Of pletely only on fine days, and almost completely 34 flowers of G. serotina, eight were pollinated closed at night. On wet or cold, dull days few on each of the first, fifth, and eighth days of their pcned female phase, five on the tenth day, and five previously the corolla lobes did not spread com- flowers were left unpollinated. For G, serotina, pletely. three flowers from each of the first, fifth, and Both G. saxosa and G. serotina are self-com- eighth day pollinations were collected two days patible (Table 1); however, flowers that were not after pollination, the stigma dissected out, fixed, pollinated and from which insects had been ex- staincd with aniline blue, and examined under eluded failed to produce any seed, so biotic pol- fluorescent microscopy to determine the extent lination is necessary for seed set. of pollen germination and pollen tube growth. Protandry. The flowers of both species are For the remaining flowers, the responsiveness of distinctly protandrous. In neither was there any each to pollination was quantified as the number obvious synchrony of male and female phases of days until (a) the flower closed completely, (b) among flowers within a plant or even a flowering closed to its greatest extent (for flowers that closed branch, so that within large plants pollen and 1987] WEBB & LITTLETON- GENTI ANA 53 Figures 1-8. — 1-7. Protandry and reaction to pollination in flowers of Genliana serotina (bars = 0.5 cm).— 1. First day open, male phase. — 2. Fourth day, stigma opening. — 3. Seventh day, stigma open, anthers near corolla. — 4. Rower closing, one day after pollination of fresh female-phase flower, — 5. Flower closed, two days after pollination of fresh female-phase flower. — 6. Flower incompletely closed, five days after pollination on eighth day of female phase. — 7. Unpollinated flower, 18 days. — 8. Unpollinated flower of G. saxosa, 30 days (bar = 0.5 cm). stigmas were presented simultaneously in differ- field conditions, little pollen usually remains by ent flowers and geitenogamy could occur. When a flower first opens, the anthers have the time the stigma opens. When the stigma opens the two lobes occupy already dehisced to present pollen exlrorsely near the position in which pollen was presented in the the center of the flower and the stigmatic lobes newly opened flower (Figs. 1, 3). The duration are tightly closed (Fig. 1). Later in the male phase, of the female phase is dependent on pollination. the corolla lobes open further, the stigma begins Reaction of the flower to pollination. Both to open, and the stamens move outwards toward species showed similar reactions to pollination, the corolla (Fig. 2), In G. saxosa, the stigma may When fresh, first-day, female-phase flowers were open and stamens recurve late on the first day pollinated, they partially closed that night and of anthesis, or as late as the fifth day. The mean failed to reopen the following day (Fig. 4). Two duration of the male phase is 1.41 days (N = 57). days following pollination the corolla lobes were In G. serotina. the stigma opens and stamens imbricate to form a neat, tight structure similar recurve between the third and seventh days to, but slightly larger than a late bud (Fig. 5). The (mean =4.73 days, N = 30). In G. saxosa, an- petals slowly turned brown and withered as the thers have usually moved halfway toward the capsule reached maturity after about four weeks. corolla when the stigma opens and have reached When the flower was pollinated on the second the corolla lobes in up to three days after that. to fifth days of the female phase, the corolla re- in G. serotina, the anthers reach the petals and acted as quickly and folded as neatly as it did usually wither one or two days after the stigma following first-day pollination. After the fifth day, opens (Fig. 3), and in some cases they eventually although the flowers and their stigmas still ap- protrude between the corolla lobes. Although peared fresh, they reacted more slowly following pollen is no longer presented in a central position pollination (Fig. 9), either taking several days to by the time the stigma opens, there may be some close or closing incompletely (Fig. 6), About one- overlap between pollen and stigma presentation third of the flowers pollinated after the fifth day within the flower, especially in G. saxosa, for of their female phase never closed completely, which the male phase is shorter. However, under There was some variation among flowers of the 54 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 17 _ 15 _ O LJ 10 . or o Ld 100^ O80 _ o (/I O o 5 _ 00 < Q60 O 40 LJ 00 20 K 1 2 4 6 8 10 DAY OF FEMALE PHASE 1 — — — r 1 r r- 2 4 6 8 10 DAY OF FEMALE PHASE NEvfe R POLUr^TED Figure 10. Average percentage of ovules produc- ing seed for flowers of Gentiana saxosa (solid dots) and G. serotina (open squares) following pollination on dif- ferent days of female phase (mean ± standard error for G. saxosa, mean only for G. serotina). Figure 9. Days taken for flowers oi Gentiana sax- ^^^^^ ^ j^jgj^ proportion of their ovules. Those osa (solid dots) and G. serotina (open squares) to close or wither following pollination on different days of female phase. pollinated on the fifth to seventh days were more variable in seed production, and seed production was related to reactivity of individual flowers. For example, a flower pollinated on the fifth day same age, but the trend to decreasing reactivity failed to close and produced no seed, whereas a with increasing age was clear in both species (Fig. flower pollinated on the seventh day closed al- 9). most completely and had 25% seed production. In the field, flowers of G. serotina reacted sim- Few flowers pollinated on the eighth day of the ilarly to those in the greenhouse. Ten fresh fe- female phase, and none pollinated on the ninth male-phase flowers were ail closed on the day or tenth days produced seed. The pattern of seed following hand pollinations, whereas eight of 10 production for flowers pollinated at different ages flowers not pollinated by hand had reopened. in G. serotina was similar (Fig. 1 0), but the small- Under fluorescent microscopy, all three stig- er sample size does not allow a detailed analysis. mas from flowers of G. serotina that had been Thus, although the corolla and stigma may pollinated on the first day of the female phase appear fresh for much longer, the functional fe- had numerous germinating pollen grains and male phase in both species is only four to eight many well-formed pollen tubes penetrating the days. Adding together male and female phases, stigma. Of the three stigmas pollinated on their one gets a reproductively functional flower life fifth day, two showed good pollen germination of five to 12 days for G. saxosa, and six to 14 and the third had only a few germinating grains. Two of the three stigmas that had not been pol- days for G. serotina. The reaction of flowers that were never pol- linated until their eighth day had no pollen ger- linated differed between species. In G. serotina, minating, and the third had good germination. the corolla lobes continued to diverge as the flow- The proportion of ovules that developed into er aged, but eventually began to close (Fig. 7), good seeds was clearly affected by the age of the finally reaching a position similar to that of a stigma when it was pollinated and related well late-pollinated flower (Fig. 6) before turning to the responsiveness of flowers to pollination, brown after an average of 26 days. However, in sharp G. saxosa the corolla lobes reached a strongly production for flowers pollinated later than the recurved position and in all but one of 1 1 flowers fourth or fifth days of the female phase (Fig. 10). showed no sign of returning to a closed position In G. saxosa, flowers pollinated on the first to (Fig. 8) and turned brown after an average of 17 fourth days of the female phase consistently ma- days. In both species some flowers had white. 1987] WEBB & LITTLETON -G£/Vr/^A^^ 55 turgid corollas for longer than a month, although responsiveness of the flower to pollination. Once the stigmas were dull and blackened by this time this occurs, pollen does not germinate on the and the stamens had altogether withered. Discussion stigma, and no seeds are produced. The begin- ning of flower life is marked by the corolla lobes opening to expose the dehisced anthers; all pollen Floral longevity of individual flowers may be is normally lost before the beginning of the fe- defined in terms of reproductive function as the male phase, so pollen availability does not de- period over which a flower is able to receive and/ termine the end of flower life, although it may or dispatch pollen. However, outside this period, affect flower longevity if the male phase is pro- flowers may perform functions not directly re- longed by a paucity of pollinator visits as in Lo- lated to their own reproductive success, as in the belia cardinalis (Devlin & Stephenson, 1985). case of supplemental pollinator attraction pro- When full senescence of a flower finally occurs, vided by late buds and older flowers. Thus, a floral changes as listed above may occur. In ad- more practical definition of floral longevity in dition, the whole flower may be aborted, even if terms of reproductive success of whole plants pollination has occurred, especially in species that may be the period for which a flower is able to use flower abortion as a means of maternal rcg- attract pollinators. For many plants, particularly ulation (Lloyd, 1980; Bawa & Webb, 1984). tropical species, floral longevity appears to be a Within a species, it is possible that the floral predetermined, endogenous characteristic with changes that occur following pollination may dif- many such species having 1-day flowers (Dob- fer from those of flowers that are never polli- kin, 1 984; Primack, 1 985). In some such species, nated. In both Gentiana saxosa and C. serotina, non-induced floral changes, which indicate that fresh female-phase flowers closed in response to the flower is no longer reproductively functional, pollination; in G. saxosa, but not G. serotina, the may occur before full senescence (indicated by reaction of never-pollinated flowers diflfered in abscission or wilting of petals). In others, flowers that flower closure did not occur and petals with- may be reproductively functional until full se- ered in a recurved position. However, the end nescence(Gori, 1983). The second major pattern of functional pollen and stigma presentation in is provided by those species in which flower life never-pollinated flowers occurred well before the may be curtailed by pollination (Kemer, 1902; morphological change of flower closure in G. se- Arditti, 1976; Stead & Moore, 1979; Devlin & rotina and corolla wilting in G". saxosa. The per- Stephenson, 1984). It is important to note that sistence of these flowers well beyond their re- for species in which floral changes are pollina- productively functionalhfe may add to the overall tion-induced, the potential flower life is still en- floral display of the plant. dogenously determined and the pollination-in- duced changes occur within this outer limit. Pollination-induced changes in flowers have been interpreted as signals that direct pollinators Gori( 1983) recognized and summarized avail- to unvisited flowers (Allen, 1898; Kemer, 1902; able data on five basic types of floral change that Arditti, 1976; Stead & Moore, 1979; Casper & follow pollination or indicate the end of repro- La Pine, 1984) or help to conceal the developing ductive function before full senescence: color seeds within pollinated flowers from predators change, termination of odor and/or nectar pro- (Allen, 1 898), or simply minimize costs of flower duction, change in flower orientation, collapse of maintenance by retaining the perianth no longer flower parts, and corolla abscission. To this may than is necessary (Kemer, 1902). Gori (1983) be added flower closure as described here for considered three aspects of the first alternative: Gentiana, and reported by Kemer (1902) for avoidance of pollinator interference within pol- Mammillaria glochidiaia. In fad, Rower closure linated flowers, increasing the pollinator's for- is likely to be the response in many species in aging efficiency and so increasing the residence which petals close regularly at night or in dull time on the plant, and increasing pollination ef- weather. Although floral changes may prevent or ficicncy by restricting pollinators to receptive (re- deter pollinator visits, the reproductive, func- productively functional) flowers. In the two tional end of flower life occurs when no viable species of Gentiana studied here, corolla closure pollen is available for dispatch and the stigma clearly signals that the flower is unavailable for ceases to be receptive. In Gentiana serotina and visits; in fact it precludes visits, and the corolla G. saxosa, the end of reproductive flower life is also tightly enfolds the developing ovary until it indicated either by flower closure or the loss of is almost mature, making it less accessible to 56 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 predators. Field experiments, as described by wet or dull days the flowers open only partly so Gori (1983) for Lupinus, would be necessary to that the anthers dehisce directly onto the stigma determine the precise function of poUination-in- (Webb, 1984a); this type of mechanism was duced flower closure in Gentiana. In many in- termed induced selfing by Schoen and Lloyd sect-pollinated species, the end of flower life is (1984). Third, flower life may be much longer signalled by corolla abscission and the devel- during weather unfavorable to pollination, or oping ovary is either inferior or enclosed within flowers may open only on suitable days with the infolded bracts or calyx lobes as in Malvaviscus floral parts protected during inclement weather arborcusiy^chh, 1984b). Corolla closure, rather (Kerner, 1902). than abscission, may be necessary to protect the When floral changes are pollination-induced, ovary in Gentiana because the large superior flowers are likely to be non-dichogamous or pro- ovary extends well beyond the small calyx lobes, tandrous because flower closure, corolla abscis- In terms of natural selection, flower life for a sion, and other reactions to pollination, all curtail particular species is likely to be a trade-off' be- the time over which pollen can be presented tween the cost of maintaining the flower in a (Lloyd & Webb, 1986). The pollination-induced receptive state and the probability that it has flower closure described here for Gentiana can been pollinated. Thus, as originally suggested by be effective only if flowers are protandrous; pro- Kerncr (1902), flower life is likely to be longer togyny would preclude pollen presentation, and for species that normally experience unpredict- adichogamy would severely limit the male phase. able weather conditions allowing fewer suitable Flower life may appear to be the simple result times for pollinator visits, for species with few, of proximate causes— especially of weather con- large flowers per plant, and for species that are ditions and pollinator availability. However, the obligately outcrossing. These suggestions are average flower life for a population, the particular supported by data on flower life that show that response of flowers to pollination, and the cues many tropical plants, particularly those flowering used to determine the time of senescence, must inthelowlandsduringthedry season, have 1 -day all be the result of natural selection. Yet, the flowers (Dobkin, 1984; Primack, 1985). Under selection of these factors has seldom received the those conditions pollination is predictable. In attention of reproductive biologists in spite of contrast, plants of higher altitudes and of tern- the important part they play in determining the perate areas have long-lived flowers, as might be success of plants as pollen or seed parents, expected when many days are unsuitable for flower visits. That many large orchid flowers with complex outcrossing mechanisms are long-lived is to be expected because they may have low rates of flower visitation. There are three strategies that might to some extent ameliorate the difliculty of unpredictable pollination. First, if flower life is pollination-de- pendent, as in the two species of Gentiana de- scribed here, then flower maintenance costs are minimized. There is, however, probably a cost in maintaining enzyme systems responsible for pol- lination-induced floral changes (Gori, 1983). Second, under conditions unfavorable to polli- nators, autogamy may occur (Kerner, 1902; Fae- gri & van der Pijl, 1979); the evolution of autog- amy often involves loss of dichogamy or herkogamy, and also a reduction of flower life (Morin, 1983). In some species selfing may be delayed until an opportunity for outcrossing has been provided or may even be a direct response to unfavorable weather conditions. In Gentiana lineata, the flowers open fully in warm sunny Literature Cited Allen, G. 1898. Flashlights on Nature. Grant Rich- ards, London. Arditti, J. 1976. Post-pollination phenomena in or- chid flowers. The Orchid Review 84: 261-268. ,N.M.Hogan&A.V.Chadwick. 1973. Post- pollination phenomena in orchid flowers. IV. Ef- fects of ethylene. Amer. J. Bot. 60: 883-888, Bawa, K, S. & C. J. Webb. 1984. Flower, fruit and seed abortion in tropical forest trees: implications for the evolution of paternal and maternal repro- ductive patterns. Amer, J. Bot. 71: 736-751. Casper, B. B. & T. R. La Pine. 1984. Changes in corolla color and other floral characteristics in Cryptantha humilis (Boraginaceae): cues to dis- courage pollinators? Evolution 38: 128-141. Devlin, B. & A. G. Stephenson. 1984. Factors that influence the duration of the staminate and pis- tillate phases of Lobelia cardinalis flowers. Bot. Gaz. 145: 323-328. & 1985. Sex differential floral lon- gevity, nectar secretion, and pollinator foraging in a protandrous species. Amer. J. Bot. 72: 303-310. Dobkin, D. S. 1984. Rowering patterns of long-lived Heliconia inflorescences: implications for visiting and resident nectarivores. Oecologia 64: 245-254. weather suitable for insect pollination, but on Faegri, K. & L. van der Pul. 1979. The Principles 1987] WEBB & LITTLETON -GENTIANA 57 of Pollination Ecology, 3rd edition. Pergamon Press, Oxford. southern hemisphere gentians. Adv. PI. Morph. 1972:417-422. GoRi, D. F. 1983. Post-pollination phenomena and Primack, R. B. 1985. Longevity of individual flow- adaptive floral changes. In C. E. Jones & R. J. ers. Ann, Rev. Ecol. Syst. 16: 15-37. Little (editors), Handbook of Experimental Pol- Schoen, D. J. & D. G. Lloyd. 1984. The selection lination Biology. Van Nostrand Reinhold, New York. of cleistogamy and heleromorphic diaspores. Biol. J. Linn. Soc. 23: 303-322. GoTTSBERGER, G. 1971. Colour change of petals in Simpson, M. J. A. & C. J. Webb. 1980. Germination Mahaviscus arboreus flowers. Acta Bot. Neerl. 20: 381-388. in some New Zealand species of Gentiana: a pre- Hminary report. New Zeal. J. Bot. 18: 495-501. Halevy, a. H., C. S. Whitehead & A. M. Kofranek. Stead, A. D. & K. G. Moore. 1 979. Studies on flower 1984. Does pollination induce abscission of Cv- clamen flowers by promoting ethylene produc- tion? Plant Physiol. 75: 1090-1093. Kerner Von Marilaun, A. 1902. The Natural His- tory of Plants, Volume 2. F. W. Oliver (translator). Blackie & Son, London. Lloyd, D. G. 1980. Sexual strategies in plants. L An hypothesis of serial adjustment of maternal in- longevity in Digitalis. Pollination induced corolla abscission in Digitalis flowers. Planta 146: 409- 414. Strauss, M. S. & J. Arditti. 1984. Postpollination phenomena in orchid flowers. XII. Eifects of pol- lination, emasculation, and auxin treatment on flowers of Cattleya porcia 'Cannizaro' and the ros- tellum of Phalaenopsis. Bot. Gaz. 145: 43-49. vestment during one reproductive session. New Thomson, G. M. 1881. On the fertilization, etc., of New Zealand flowering plants. Trans. Proc. New Zeal. Inst. 13: 241-288. ence between the presentation of pollen and stig- Webb, C. J. 1984a. Constraints on the evolution of Phytol. 86: 69-79. — & C. J. Webb. 1986. Avoidance of interfer- mas in angiosperms. I. Dichogamy. New Zeal. J. Bot. 24: 135-162. Mayak, S. & A. H. Halevy. 1980. Flower senes- cence. In K. V. Thimann (editor), Senescence in Plants. CRC Press, Boca Raton, Florida. MoRiN, N. 1983. Systematics of Githopsis (Campan- ulaceae). Syst. Bot. 8: 436-468. Philipson, W. R. 1972. The generic status of the plant breeding systems and their relevance to sys- tematics. In W. F. Grant (editor), Plant Biosys- tematics. Academic Press Canada, Don Mills, On- tario. — . 1984b. Hummingbird pollination of Mal- vaviscus arboreus in Costa Rica. New Zeal. J. Bot. 22: 575-581. NOTES ON THE BREEDING SYSTEMS OF SACOILA LANCEOLATA (AUBLET) GARAY (ORCHID ACEAE)^ Paul M. Catling^ Abstract To document breeding systems in the widespread neotropical terrestrial orchid, Sacoila lanceolata, poUination and seed development were studied in the field and in cultivated plants. In the southern Florida study area, plants of var. lanceolata were not pollinated and hummingbird pollinators were apparently absent. When plants from southern Florida were moved to a situation where hummingbirds were abundant in southern Ontario, hummingbird-pollination was observed on numerous occasions and the incidence of pollination was approximately 90%. Pollination experiments demonstrated a reliance on pollen vectors in plants of var. lanceolata from central Guyana, where a variety of hum- mingbird pollinators are available, but the plants of the same variety from southern Florida were found to be agamospermic. Examination of serial sections of ovaries in successive developmental stages indicated that agamospermy is by adventitious embryony, the embryos (one or more) being formed by proliferation of the inner integument. Adventitious embryony can be detected through association with polyembryonic seed, is characteristic of Florida populations of var. lanceolata, and occurs also in portions of the tropical range. Plants of S. lanceolata var. paludicola from southern Florida were found to self-pollinate. The pollinator-independent breeding systems in southern Florida populations of S. lanceolata var. lanceolata and var. paludicola and the apparent absence of races totally reliant upon pollen vectors are associated with pollinator-paucity. Sacoila lanceolata (Aublet) Garay var. lanceo- have pollinator-independent breeding systems in lata is a reddish- to orange-yellow- or occasion- southern Florida. Since the breeding systems of ally pale greenish-flowered, terrestrial orchid with tropical and subtropical terrestrial orchids are a broad neotropical distribution extending from relatively poorly known, a study was undertaken northern Florida and northern Mexico to north- to document the breeding systems of 5". lanceo- em Uruguay (Luer, 1972). The smaller-flowered lata, var. paludicola Luer is restricted to extreme southern Florida [the Fahkahatchee Strand in Collier Co. (Luer, 1971a), Kendall Hammock in Dade Co. (pers. obs.), and from one location in the Everglades (McCartney, 1985)] and the Ca- ribbean region (based on examination of speci- Methods HELD STUDIES OF POLLINATION IN SOUTHERN FLORIDA In order to gather information on natural pol- mens at AMES, DAO, SEL, and FTG— aero- lination, populations of 5. lanceolata var, lan- nyms from Holmgren et al., 1981). Both var. ceolata were observed for an overall total of 20 lanceolata and var. paludicola have gaping tu- hours in southern Florida during mid-May 1978 bular flowers with an adnate spur (Fig. 1). In and 1984. The presence of potential pollinators, terms of flower color and morphology and ab- including hummingbirds and large bees partic- sence of a detectable odor, the flowers of both ularly, was noted. Large bees are the regular pol- varieties are representative of the bird pollina- linators of some related species (Pijl & Dodson, tion syndrome (Pijl & Dodson, 1966). Casual observations of seed development in a 1966; Catling, 1983). Since pollination of orchid flowers involves few cultivated plants that were maintained in the removal of the pollinarium from the anther, it absenceofany potential pollen vectors suggested is possible to obtain an approximation of the that both var, lanceolata and var, paludicola may incidence of pollination by recording pollinaria ' Living plants of Sacoila lanceolata var. paludicola were provided by C. A. Luer, H. Brown, and G. Matous. C. A. Luer and V. R. Brownell assisted with field work. Useful criticisms were provided by S. C. H. Barrett (University of Toronto), C. A. Luer (Missouri Botanical Garden), N. R. Morin (Missouri Botanical Garden), and N. H. Williams (Univ. of Florida). W. Wojtas kindly assisted with the anatomical work. ^ Agriculture Canada, Biosystematics Research Institute, Central Experimental Farm, Ottawa, Ontario, Canada KIA 0C6. Ann. Missouri Hot. Gard. 74: 58-68. 1987. 1987] CATLING-BREEDING SYSTEMS OF SACOILA 59 Figure 1. A, B, D. S. lanceolata var. lanceolata.—A. Frontal view of flowers, Immokalee, Collier Co., Florida, 15 May.— B. Flower spike of cultivated plant from central Guyana, South America, 13 January. — D. Side view of flowers, Immokalee, Collier Co., Florida, 15 May.— C. S. lanceolata var. paludicola, flower spike, cultivated plant from Fahkahatchee Strand, Collier Co., Florida, 15 February. removal. This is more easily recorded than the ed by malformation or drying out of the viscid- presence of pollen tubes in the deteriorating col- ium or by the difficulty of attaching to an existing umn of faded flowers. It is, however, only an excess load of pollinaria. The incidence of pol- approximation since pollinaria removal is oc- lination in southern Florida, as determined by casionally (although apparently rarely) prevent- the absence of the pollinaria in faded flowers, 60 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 was determined by examining 500 flowers from tying the capsule and determining the presence a total of 100 inflorescences representing eight or absence of embryos in the first 200 embryo locations. sacs observed. This was followed by a scan of a few thousand to make certain that the value ob- tained was representative. If the value was con- sidered not representative, two more samples of 200 were scored and the average percentage was then recorded. STUDIES OF POLLINATION OF TRANSPLANTS Plants from the Sarasota and Immokalee areas of southern Florida were observed for approxi- mately 33 hours after transplanting into a rural setting in southeastern Ontario, Canada, in late May 1984. The presence of potential pollinators was again recorded. The approximate incidence ANATOMICAL STUDY Each of the three groups of plants used in the ers. of pollination was determined by pollinaria re- pollination experiments was studied anatomi- moval (see above) in five groups of five experi- cally to determine whether or not pseudogamy mental plants each, including a total of 429 flow- (asexual seed development requiring polHnation) was operating and to determine the method of agamospermy in plants producing seed without any pollination. Serial sections of ovaries were examined in successive developmental stages. Ovaries fixed and preserved in formalin-acetic acid-alcohol (FAA) were dehydrated, embedded in paraffin, sectioned, mounted, and stained us- ing a safranin-hematoxyhn combination (Lillie, 1969; Jensen, 1958). Mature seeds of experi- mental plants were stained for examination using the differential stain technique described by Ow- czarzak (1952), The percentage of polyembryo- nic seed was determined in the same way as the percentage of embryo sacs containing embryos POLLINATION EXPERIMENTS Pollination experiments were performed on plants maintained in a glass house in Ottawa in April and May 1984 from which potential pol- linators (insects, hummingbirds) were excluded. Voucher specimens are contained in the Agri- culture Canada herbarium of the Biosystematics Research Institute in Ottawa, Ontario (DAO). The experiments were performed on three groups of plants: 1) 60 plants of 5". lanceolata var. lan- ceolata, four from each of 15 localities in south- ern Florida distributed in a broad band, ca. 30 km wide, from Sarasota south to Immokalee; 2) three plants of 5. lanceolata var. lanceolata from near Mahdia, central Guyana, South America; and 3) six plants of 5. lanceolata var. paludicola (see above). STUDY OF DRIED MATERIAL An attempt was made to determine the dis- including three from the Fahkahatchee Strand, tribution of breeding systems through the ex- Collier Co. and three from Kendall Hammock, amination of herbarium material from AMES, Dade Co., both in southern Florida. MICH, SEL, FTG, and DAO (acronyms from Starting from the base of a spike, each se- Holmgren et al., 1981). This is made possible, quence of five flowers was treated in the same to a degree, by association of various morpho- way. Following the first day after all flowers in logical features with a specific breeding system, the sequence had fully opened, the first flower Plants were considered agamospermic if they was left undisturbed, the pollinarium was re- possessed any polyembryonic seed. Relatively moved from the second flower, the third was self- small flower size was considered potentially in- pollinated, the fourth pollinated with pollen from dicative of autogamy (sec Omduff", 1969), Lack a different flower on the same plant (geitonoga- of expansion of some ovaries in fruiting material mous polHnation), and the fifth was pollinated was considered suggestive of -obligately cross- with pollen from a flower on a different plant pollinated races. (cross-pollination). With the exception of the plants from Guyana, cross-pollination was car- ried out using plants from different localities. Each ovary was appropriately tagged to indicate the treatment of the corresponding flower. The number of expanded ovaries was recorded as well Results FIELD STUDIES OF POLLINATION IN SOUTHERN FLORIDA In southern Florida, insects (including larger as the percentage of embryo sacs containing em- bees) were present but were not observed visiting bryos. The latter value was estimated by emp- the flowers of 5. lanceolata var. lanceolata. No 1987] CATLING-BREEDING SYSTEMS OF SACOILA 61 Figure 2. Ruby-throated Hummingbird {Archilochus colubris) pollinating Sacoila lanceolata var. lanceolata from Sarasota Co., Florida, 25 May. — A. Female probing flower directly through the floral tube. — B. Female withdrawing with a pale yellowish pollinia attached to the tip of the bill.— C. Male probing a flower from the right side below the lip. — D. Male probing flower directly. hummingbirds were observed. There was no evi- were 15 minutes to two hours apart and were dence of pollination, in the form of pollinarium most regular in the morning between 9 a.m. and removal, in any of the eight southern Florida 11:30 a.m. Visits by one or more females (i.e., locations. female visits) involved a direct probing of the flowers (Figs. 2A, 3A), the pollinia becoming at- tached, by the elongate cushion-type viscidium STUDIES OF POLLINATION OF TRANSPLANTS , , , , ,, ^^ X^^ ^ ^ that sheaths the rostellum (Fig. 3C, D, E, and In southeastern Ontario, large insects includ- Greenwood, 1982), to the distal portion of the ing large bees were common, but they totally bill (Figs. 2B, 3B). Male visits involved probing ignored the flowers. Ruby-throated Humming- from the side and below the lip approximately birds {Archilochus colubris) were also common. 50% of the time (Fig. 2C, D). Probably as a con- These birds regularly visited the flowers of S. sequence of this "robbing," male visits resulted lanceolata var. lanceolata and acted as effective in pollinia removal only eight of 46 times, as pollinators. Females were observed visiting in- compared with 15 of 25 in the case of female florescences on 25 separate occasions and males visits. In the 25 experimental plants, which were on 46. A visit usually involved probing three to observed being pollinated by the hummingbirds, five flowers on an inflorescence and visiting one the incidence of pollination was 90% (i.e., 386 to three inflorescences in a group of five. Visits of 429 flowers). 62 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 I 10 mm Figure 3. A, B. Diagrams of a Ruby-lhroated Hummingbird {Archilochus colubris) removing pollinia from a flower of Sacoila lanceolata var. lanceolata. — A. Bird with bill inserted in flower, prior to upward movement that will bring it into contact with the viscidium (darkened). C. Column viewed from below orior to removal of ooUinarii with D. Column viewed from below after removal of pollinarium leaving the long narrow rostellum.— E. PoUinarium viewed from below showing viscidium (darkened) and pollinia. All diagrams based on material from Sarasota Co., Florida. POLLINATION EXPERIMENTS Pollination was clearly necessary for seed de- velopment in S. lanceolata var. lanceolata from central Guyana (Table I). In these pollinator- dep)endent plants, the flowers last for 10-15 days in the absence of pollination. Pollination at any time is followed by fading in two or three days. In 5. lanceolata var. lanceolata from southern Florida, seed develop>ed regardless of pollinar- ium removal (Table 1), and these plants were clearly autonomously agamospermic. The flow- ers lasted 5-15 days in the absence of pollination, but pollination resulted in fading within two days. Seed development occurred in undisturbed flowers of 5^. lanceolata var. paludicola, but not autogamy (self-pollination) or pseudogamy (pol- lination-induced agamospermy) in this variety. Self-pollination occurred after the flowers had been open for one or two days. The flowers are short-lived, lasting for approximately five days. The mechanism of self-pollination is a simple one involving contact between the stigmatic sur- face and the pollen masses (Figs. 4B, 5). Such contact is not possible in var. lanceolata because of the separation resulting from the relative lengths of the pollinia and the basal part of the column (Fig. 4A). ANATOMICAL STUDY The Guyana plants of var. lanceolata and plants when the pollinarium was removed from the of var, paludicola from southern Florida dem- flower at an early stage (Table 1), indicating onstrated a normal sequence of pollination, pol- 1987] CATLING- BREEDING SYSTEMS OF SACOILA 63 Table 1 . Pollination experiments with Sacoila lanceolata. Treatment No. of Plants 5". lanceolata var. lanceolata— Guyana Undisturbed 3 Pollen removed 3 Self-pollination 3 Geitonogamous-poUination 3 Cross-pollination 3 S. lanceolata var. lanceolata—Souih Florida Undisturbed Pollen removed Self-pollination Geitonogamous-poUination Cross-pollination 60 60 60 60 60 S. lanceolata var. paludicola— South Florida Undisturbed Pollen removed Self-pollination Geitonogamous-poUination Cross-pollination 6 6 6 6 6 No. of Ovaries 6 6 6 6 6 200 180 180 180 180 25 12 12 12 12 No./% Ovaries Expanded 0/0 0/0 6/100 6/100 6/100 200/ 1 00 180/100 1 80/ 1 00 1 80/ 1 00 180/100 25/10 0/0 12/100 12/100 12/100 No./% Ovaries with Seed* 0/0 0/0 4/66 4/66 4/66 200/ 1 00 1 80/ 1 00 1 80/ 1 00 180/100 1 80/ 1 00 25/10 0/0 12/100 12/100 12/100 % Sacs with Embryos* 50-100 60-100 60-100 90-100 97-100 96-100 97-100 97-100 95-100 95-100 95-100 95-100 As a percentage of the total ovaries tested len tube growth, fertilization, and embryo de- ,,„, „ ^. r- ♦!• ino'>\ T 1 . r STUDY OF DRIED MATERIAL velopment (see Catling, 1982). In plants of var. lanceolata from Florida, the gametophyte de- Many more collections and some supporting generated and one or more cells of the inner in- fieldwork would be necessary to allow a reliable tegument proliferated to become embryos. The assessment of the distribution of different breed- proliferation of these cells was indicated by the ing systems throughout the range of »S. lanceo- more deeply staining protoplasts, relatively large lata. However, an appraisal of the extent to which nuclei, and well-developed nucleoli (Fig. 6). Pro- the breeding systems of the southern Florida liferation had initiated in the ovaries of flowers populations are unique was possible with the ma- open for five days and may have initiated earlier terial examined, but was not evident in mature ovaries with buds on the point of opening. Using ovaries of in- ic Agamospermy, as evidenced by polyembryon- ic seed, was found in all fruiting plants from creasing age within an inflorescence, it was pos- Florida and in some plants from Guatemala, Be- sible to trace the darkly staining and proliferating lize (British Honduras), and Bolivia. In some micropylar integument to embryos in mature cases this was associated with non-opening (i.e., seeds. The seed resulting from adventitious em- cleistapogamous, see Sheviak, 1982) flowers (for bryony (Fig. 7C) differs from that resulting from example, district of Pelen, Guatemala, 12 June fertilization (Fig. 7A, B) in having a proportion MICH) of the seeds polyembryonic (range 28-95%, mean rence of agamospermy within the main tropical 7 1.3%, standard deviation 1 7, based on 1 5 flow- high ers representing 1 5 different southern Florida altitude, a situation that involves some of the populations). same effects as high latitude, and the sample is Five capsules from flowers cross-pollinated on not large enough or sufficiently well documented the first day of opening and five capsules from to reliably reflect a trend, flowers from which the pollinarium was removed Relative! demonstrated similar levels of polyembryony mm long), 4-1 suggestive (range 56-94%, mean 73.5%, standard deviation characteristic of plants from a number of Carib- 1 7.9; range 30-84%, mean 57.2%, standard de- bean islands (for example, Bahamas, St. Vincent, viation 23.5, respectively) AMES and FTG) 64 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 3 E E in o Figure 4. A. Column of Sacoila lanceolata var. lanceolata viewed from below (left) and diagrams of cross- sections (right) based on material from Sarasota Co., Florida. — B. Column of Sacoila lanceolata var. paludicola viewed from below and diagram of cross-section (right) of flowers originating from Collier Co., Florida. C cross-seclions illustrated on the right-hand side of the figure: P, pollinarium; PG, pollen germinating; S, stigmalic surface; V, viscidium. fruit set, suggestive of obligate cross-pollination, (Jones, 1977), Dactylorhiza (Dressier, 198 1), was restricted to Costa Rica and northern South Zygopetalum (Dressier, 198 1), and Pterygodium America. (Schelpe, 1970). Autogamy is much more prev- alent than agamospermy in vascular plants gen- DiscussiON erally and in the orchid family, where it has been Agamospermy is uncommon in the orchid reported in over 60 genera (Calling, unpubl. data). family, having been previously reported only in In S. lanceolata var. lanceolata, it is not known Zeuxine, Nigritella, and Spiranthes (Mahesh- whether agamospermy is facultative. Although wari, 1952; Catling, 1982), Prasophyllum (Bates, there is no evidence of seed resulting from cross- 1984a), Microtus (Bates, 1984b), Paracaleana fertilization in terms of a lower incidence of poly- 1987] CATLING- BREEDING SYSTEMS OF SACOILA 65 ■ h C i > <^ <^ ^> J \ r ;V V / (^ *4 V s):^ s; >•- • .^A I 0-5 mm J Figure 5. Cross-section of column of S. lanceolata van paludicola, from Collier Co., Florida. This section represents the position Cs-C^ in Figure 4B. AC, anther cap; P, pollinarium; PG, pollen germinating; S, stigmatic surface. embryony, this may have been the result of cross- doubt that these observations are indicative of pollinations using genetically identical individ- the pollination mechanism in various other sit- uals vt^ith some degree of self-incompatibility. Al- uations where one or more species of humming- though the crossings involved plants from dif- birds are available. ferent localities in southern Florida, it is The suggestion of a lack of natural pollinators conceivable that the different populations had in southern Florida pineland is of interest insofar the same agamospermic origin and are geneti- as it may provide an explanation for the polli- cally identical. nator-independent breeding systems. Although Pollination by hummingbirds in S. lanceolata self-pollination and agamospermy are associated is to be expected on the basis of various floral with pollinator-paucity and colonization of new features such as the tubular, horizontally orient- territory (for example, Allard, 1965; Jain, 1976; ed, reddish flowers without internal marking and Lloyd, 1978) the actual absence of pollinators lacking odor (Austin, 1 975; Pijl & Dodson, 1 966), has not often been well established (for example, but no previous observations of hummingbird Kevan, 1972); nor has "newness" been quanti- pollination have been reported. The only feature of characteristically bird-pollinated orchid flow- In the southern Florida pinelands in May, £'r- ers that is lacking is a dark pollinarium (Dressier, ythrina herbacea and Ipomea microdactyla are 1971), that of 5. lanceolata being pale yellow. among the few characteristic hummingbird blos- Although the observation of hummingbird-pol- soms available, and these species were not ob- lination reported here involved transplanted and served near colonies of var. lanceolata. Only one cultivated plants, there seems to be no reason to species of hummingbird {A. colubris) is present, fied. 66 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Figure 6. A, B. Cross-sections of ovules of S. lanceolata var. lanceolata from Sarasota Co., Florida. — C. Longitudinal section, g = degenerate gametophyte, ii = proliferating inner integument, oi = outer integument. Material from Sarasota Co., Florida. and by April and May it has already migrated soms on a year-round basis (Grant & Grant, through the area (Austin, 1975). Breeding of ^. colubris south of Lake Okeechobee may be very 1968). Populations of five other tropical orchids {Ep- localized (Sprunt, 1954), and there is very little idendrum rigidum, E, nocturnum, Encyclia evidence of breeding in southern Florida (Rob- cochleata var. triandra, E. boothiana var. ery- ertson, 1974). Thus there is relatively little to thronoidcs and Bletia purpurea) in many parts attract hummingbirds to the vicinity of many S. of southern Florida possess a column structure lanceolata colonies in southern Florida during that promotes self-pollination. This is in contrast the May blooming period, and there is only one to parts of (or all oO the warmer continental neo- potcnlial hummingbird pollinator, which is ap- tropics where these same species have a column parcntly not abundant. The var. paludicola also structure adapted to cross-pollination, or where exists in the absence of a diverse hummingbird- this latter column structure is at least predomi- poUinated flora in southern Florida, although a nant (Luer, 1971b, 1972; Pijl & Dodson, 1966; few bromeliads exhibiting the syndrome do flow- pers. obs.). Pollinators are not clearly lacking in er simultaneously in the hammocks. The situa- the case of these species. It is possible that con- tion over much of the range of var. lanceolata is linual near extinctions due to frost (Singleton, quite different since many different humming- 1936; Stowers & Le Vasseur, 1983), hurricanes bird species are available and there is a diversity (Craighead & Gilbert, 1962; Alexander, 1967) and continuity of hummingbird-pollinated bios- and sea-level fluctuations (Fairbridge, 1974; 1987] CATLING-BREEDING SYSTEMS OF SACOILA 67 3 S E E B •i V 1mm ^:i^ c Figure 7. A, B. Seed of Sacoila lanceolata var. paludicola,—A. Collier Co., Florida. — B. Dade Co., Florida C. Seed of S. lanceolata var. lanceolata from Sarasota Co., Florida. Long, 1974) resulted in a strong selection for colonizing ability, regardless of pollinator-avail- ability. With their terrestriial habit and drier el- evated habitats, it seems unlikely that the two Bates, R. 1984a. Apomixy in four south Australian (editors), The Genetics of Colonizing Species. Ac- ademic Press, New York. Austin, D. F. 1 975. Bird flowers in the eastern United States. Florida Scientist 38: 1-12. varieties of S. lanceolata would be as strongly influenced by these factors. Consequently polli- nator-paucity is considered to provide an ade- quate explanation for their pollinator-indepen- dent breeding systems in southern Florida. species of Prasophyllum R.Br. J. Native Orchid Soc. South Austr. 8(4): 38-39. — . 1984b. The genus Microtus R.Br. (Orchida- LlTERATURE CiTED Alexander, T. R. 1967. Effect of hurricane Betsy on the southeastern Everglades. Florida Acad. Sci. ceae): a taxonomic revision with notes on biology. J. Adelaide Bot. Gard. 7(1): 45-89. Catling, P. M. 1982. Breeding systems of north- eastern North American Spiranthes (Orchida- ccae). Canad. J. Bot. 60(12): 3017-3039. . 1983. Pollination of northeastern North American Spiranthes (Orchidaceae). Canad. J. Bot. 61(4): 1080-1093. Craighead, F. C. & V. C. Gilbert. 1 962. The effects of hurricane Donna on the vegetation of southern Florida. Florida Acad. Sci. Quart. J. 25: 1-28. species. Pp. 49-76 mH.G. Baker &G.C.Stebbins Dressler, R. L. 1971. Dark pollinia in humming- Quart. J. 30: 10-23. Allard, R. W. 1965. Genetic systems associated with colonizing ability in predominantly self-poUinaled 68 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol.. 74 bird-pollinated orchids, or do hummingbirds suf- fer from strabismus? Amer. Naturalist 105: 80- 83. — . 1981. The Orchids, Natural History and LuER,C. A. 1971a. A\sineiy of Spiranlheslanceolata in Florida. Florida Orchidist 14: 19. . 1971b. Abnormal development of the an- Classification. Harvard Univ. Press, Cambridge, Massachusetts. ther— a report of two cases. Florida Orchidist 14: 26-29. — . 1972. The Native Orchids of Florida. New Fairbridge York Botanical Garden, Bronx, New York. ordinsouthFlorida. Pp. 223-232/72 P.J. Gleason Maheshwari, P. 1952. Polyembryony in angio- (editor). Environments of South Florida: Present and Past. Miami Geological Society Mem. 2. Grant, K. A. & V. Grant. 1968. Hummingbirds and Their Flowers. Columbia Univ. Press, New York. Greenwood 1982. Viscidium types in the Spiranthinae, Orquidea (Mex.) 8(2): 283-310. Holmgren, P. K., W. Keuken & E. K. Schoreld. 1981. Index Herbariorum, Part 1, The Herbaria of the World. Dr. W. Junk, Boston. Jain,S. K. 1976. The evolution ofinbreeding in plants. Annual Rev. Ecol. Syst. 7: 469-495. Jensen, W. A. 1 958. Botanical Histochemistry, Prin- ciples and Practice. W. H. Freeman and Co., San Francisco. 1952. A rapid method for mounting sperms. Palaeo-botanist (Lucknow) 1: 319-329. McCartney, C. 1985. Orchids of Florida— the or- chids of Everglades National Park— 1. Amer. Or- chid Soc. Bull. 54(3): 265-276. Ornduff, R. 1969. Reproductive biology in relation to systematics. Taxon 18: 121-133. OWCZARZAK, A. pollen grains. Stain Technol. 27: 249-251. PijL, L. van der & C. H. DoDSON. 1966. Orchid Flowers: Their Pollination and Evolution. Univ. of Miami Press, Coral Gables, Florida. Robertson, W. B., Jr. 1974. The southern Florida avifauna. Pp. 414-452 in P. J. Gleason (editor), Environments of South Florida: Present and Past. Miami Geological Soc. Mem. 2. Jones, D.L. 1977. Miscellaneous notes on Australian Schelpe, E. A. 1970. Self-pollination, cleistogamy Orchidaceae II. Reduction of six teratolocical forms 26-1 Kevan flowers. J. Ecol. 60(3): 831-847. LiLLiE, R. D. 1969. H. J. Conn's Biological Stains The Williams and Wilkins Co., Baltimore. Lloyd, D. G. 1978. Demographic factors and self- and apomixis among South African orchids. South African Orchid Society Journal, March: 9-10. Sheviak, C. J. 1982. Biosystematic study of the Spi- ranthescernua complex. New York Slate Museum (Albany) Bull. 448, 73 pp. Singleton, G. 1936. The freeze of 1934. Florida Acad. Sc. Proc. 1: 23-33. fertilization in plants. Pp. 67-88 in O. T. Solbrig Sprunt, A., Jr. 1954. Florida Bird Life. Coward- (editor). Demography and the Dynamics of Plant Populations. Blackwell, Oxford. McCann Inc. and National Audubon Society, New York. Long 1974. Origin of the vascular flora of Stowers, D. M., Jr. & M. LeVasseur. 1983. The southern Florida. Pp. 28-36 in P. J. Gleason (ed- itor). Environments of South Florida: Present and Past. Miami Geological Society Mem. 2. Florida freeze of 1 3 January 1 98 1 : an impact study of west-central Florida. Florida Scientist 46: 72- 83. FLOWER AND FRUIT BIOLOGY IN SOUTHERN SPANISH MEDITERRANEAN SHRUBLANDS 1 Javier Herrera Abstract Flower and fruit biology was studied in a coastal, southern Spanish scrub community composed of 30 plant taxa. Data on breeding systems; rewards offered to vectors; flower, fruit, and seed sizes; and fruiting intensities are reported. Most taxa in the community have insect-pollinated, hermaphroditic flowers that are largely unspecialized in morphology. Dioecious species are relatively well represented (27% of the total), as are vertebrate-dispersed species (43%). Bagging experiments demonstrated that pollinators were required for maximum fruit production, but the existence of incompatibility systems was not tested. When the relationship between fruiting intensity and the ability to perform vegetative regeneration was investigated, it was found that sprouting taxa had, on average, lower fruit production than those that were unable to sprout. Low fruit production is discussed in relation to reproductive allocation trade-offs. Mediterranean-type vegetation has been the to investigate the reproductive biology of a subject of research for investigators who wish to southern Spanish sclerophyllous scrub commu- emphasize convergence phenomena in geograph- nity. Flower and fruit features in a number of ically distant areas with similar environmental taxa are used to elucidate reproductive patterns, factors (Specht, 1969; Mooney & Dunn, 1970; The relationship between sprouting behavior (the Cody & Mooney, 1978). Also, a great emphasis production of new stems from established rhi- has been put upon plant development and the lignotubers, or burls; James, 1984) and adaptive features of plants in this highly seasonal pollination-reproduction variables is also inves- climate (Mooney & Parsons, 1973; Mooney et tigated. Pollination relationships at the com- al., 1974; Kummerov, 1983). Comparatively lit- munity level will be dealt with elsewhere (J. Her- tle is known, however, about other characteris- rera, in prep.), tics in the biology of mediterranean species, such as their reproductive biology. The paucity of in- formation is particularly noticeable with respect Study Area and Methods This study was conducted in the Donana Bi- to plants living in the Mediterranean region itself ological Reserve (Dofiana National Park, Spain), (but see C. M. Herrera, 1981, 1984; Jordano, The reserve is located on the Atlantic coast of 1982, 1984, for plant-frugivorous bird relation- southwestern Spain, in an area with a mediter- ships, and J. Herrera, 1985, for nectar secretion rancan-type climate where the vegetation is com- pattems in scrub). Some information is available posed mainly of mediterranean sclerophyllous for mediterranean areas in America, Australia, shrublands with some planted pine woods. An- and South Africa (for example, Moldenke, 1975; nual precipitation averages 537 mm. Mean an- Specht et al., 1981; Kruger, 1981). But in spite nual temperature is 16°C, January being the cool- of this, our present knowledge of the reproduc- est month (9.8°C) and July the hottest (24.6°C). tive biology of mediterranean shrublands is low Temperatures rarely descend below zero, and compared to our knowledge of tropical (for ex- summer drought covers five months on average ample, Frankie et al., 1 974, 1 983; Heithaus, 1 974; (May through September). The soil is sandy, and Bawa, 1979; Bawa & Opler, 1975; Opler et al., maximum elevation above sea level is 30 m. 1980) and temperate plant communities (for ex- Basically the vegetation encompasses two types ample, Mosquin, 1971; Kevan, 1972; Pojar, 1974; of scrub formations, distributed according to to- Reader, 1977; Primack, 1983). pographic and cdaphic factors. Where the level This paper presents part of a study designed of the underground water table is relatively near ' This study received financial support from the Spanish Comision Asesora de Investigacion Cientifica y Tecnica (CAICYT), through a grant (82/264) to Salvador Talavera (Departamento de Botanica, Facultad de Biologia, Universidad de Sevilla). I thank Dr. P. E. Gibbs for correcting the English, and two reviewers for helpful comments on the manuscript. ^ Departamento de Botanica, Facultad de Biologia, 41080 Sevilla, Spain. Ann. Missouri Bot. Gard. 74: 69-78. 1987. 70 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 soil surface, the scrub becomes dominated by hygrophytic species (heath). Otherwise, a highly xerophytic scrub vegetation is found (see AUier el aL. 1974: Rivas-Martinez et al., 1980). The The volume per flower was measured by the length of the column, in mm, inside 5 fi\ micro- pipettes. Concentration, on a weight : weight ba- sis, was measured in two AT AGO refractometcrs most representative species, both in hygrophytic (models N 1 and N2) compensated to ambient and xerophytic scrub, were selected for study giv- temperature. The milligrams of nectar sugar plus ing a total of 30 taxa. From December 1982 diluted solids (Inouye et al., 1980) were com- 1984 the study plot was visited puted by the product of volume x concentration March weekly, and data on flowering phenology, pol- (Bolten et al., 1979). lination relationships, and flower-fruit biology Percent fruit production in of the species were gathered. Here I report only flowers of the species was estimated from flower open on aspects of flower and fruit biology. and ripe fruit counts on marked branches. Tn the Individual plants or branches were marked be- same individual plants that were used to estimate fore flowering, and their area estimated from bagged maximum and minimum diameters. Rowers with white nylon mesh (or with glassine paper were counted every week during the time of study, bags in anemophilous taxa) to determine fruiting and the maximum numbers registered for the intensities when pollinators were excluded. Bag- plants of a species were averaged to give an es- timate of flower production per unit area. Fresh samples of flowers and fruits of all taxa ging experiments were not carried out with dioe- cious taxa. Samples of fruit were collected and oven dried to a constant weight, and the number were taken to determine the most outstanding ofseeds, along with the weights ofthe whole fruit, external features, such as dimensions, color, and all seeds, and that of an individual seed were sex. Ten to 20 flowers of each species were mea- averaged and recorded. Notes on fruit and flower sured (length, maximum and minimum diame- predation were also taken and, when possible, ters), and 20 to 500 complete flowers without the agents responsible were identified. their pedicels were air dried and weighed. The maximum dimension of a flower was found to be directly correlated with its dry weight (r^ = The ability to perform vegetative regeneration after complete destruction of aboveground bio- mass (sprouting) was assessed for every species. 0.806, N = 30, P < 0.001). Therefore dry weight Data on sprouting of these species were derived has been used subsequently as an estimate of from careful observations carried out in the study flower size, since it is less dependent on the ar- area on plants damaged by fire, herbivores, or chitecture ofthe corolla than on the maximum human disturbance during the years 1982 through dimension. Pollination modes of taxa were de- 1985. termincd from external features and visitor cen- suses (J, Herrera, in prep.). Flower forms were referred to those of Faegri and van der Pijl ( 1 979). Pollen production and the number of ovules in the ovary of each flower were determined for Results FLOWER BIOLOGY The names ofthe species studied, together with 10 to 15 flowers per plant species. Ovules were their most distinctive floral features, arc sum- counted under a dissecting microscope. Pollen marized in Table 1, Our set of mediterranean production was assessed in the same flowers by plants consists of 30 taxa in 17 families and 25 macerating one or two anthers in a known vol- genera. Most families contribute one or two ume of detergent-safranine solution and count- species, with only Cistaceae, Leguminosae, La- ing the number of grains in 10 replicates of 5 m1- biatae, and Ericaceae being relatively well rep- Pollen-ovule ratios of hermaphroditic species resented (5, 4, 3, and 3 species, respectively). were then compared with those given by Cruden (1977). Pollination by insect vectors is dominant in the community, where entomophilous species To investigate nectar secretion, flowers were account for more than 80% of the total (Table 1). observed in the field and in the laboratory under Only five species rely on wind for pollen dis- a dissecting microscope. In doubtful cases, the persaL Hermaphroditism is the most common arrival of insect visitors to flowers was precluded breeding system with 21 taxa (70%), although bagg dioecious species are relatively well represented flowers were examined after 24 hours and, when (27%). Thymus tomentosus is the only species possible, the accumulated nectar was quantified, with a diflerent sexual condition (gynodioecy). 1987] HERRERA- FLOWER & FRUIT BIOLOGY 71 00 -* a o X CO en c o •- 3 ■ r^ 03 u .a o ■-" 1 - o Cu X B o "o o c X QO C o c u cd a> (A S 2 a E 1> C cd cd o I c o t3 * r* CO on a Cd '■5 c t/1 W^ J- ■ Cd Oh "a c O Xi 2 O V5 o x> 6 3 C u O t c > "O V5 rn (/I C! cd O --5 W 3 Cd O Cd oh C o o CO o 13 E E rj UJ < 3 cd e Qu E a E o o 2 c o (A o u _3 13 > i.2 O. cd E 3 Z O E O • « Oh Cu u Ph o a 0^ On y^ o O O /-ifn(NiAii/->»AiTfr^Ou^r*%ON ON r--m^ w-i^H(N ^-^ v-i 7 00 I od m ir^ t ■^ oo NO 00 NO 00 -^ u^ ■^ "J^ I (N > ^ cd ex 00 >>>>>> P^ - E >> ^ OOOO^ aoD^ D.? >i^ >> >. T3'OX3 cdT3T3 cd^ ^ XJ TD TD "O TD 2 -O TS TD TD Cd TD T3 -a WWUJ 3 I a: 3 CA lA o s. 3 5 3 ^ o to 3 o Q i 13 hJ (3 :c: E cd t3 to 3 ^ ^ a a; a; ^ to 3 to 5 cO nJ 3 3 u ^ ■^ CO O S2 ^ O O r^ O to 3 s to 3 ^ O 3 s >3 o PQ ■Si =5 to 3 to 5 3 C3 s to 3 ^ O Pi s 3 O to 3 I c Co ^ ^ i^ t/1 3 O o o o c 00 o 3 O o o 3 tA 3 O ex o E Cd E o CA (A O oo (A 3 O 4 r^ # r^ ^ CA .:; 3 TD O o .-^ cd Cd Cd Cd' 4 r^ ex o E o c DC UJ — r^ o c xT ao ISM (A C "-5 'S, c a PlH C z 72 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 5 A o LU GD A aa A 3 LLI 2 1 i. ^ A A •A» A A A U_ 1 i 1 1 Among en tomophilous taxa, pollen and nectar are offered by approximately the same number of species (12 and 13, respectively). However, since wind-pollinated taxa are also occasionally used as a pollen source by insects (pers. obs.), this food material is more readily available in our community than is nectar, at least in terms of plant taxa. Furthermore, we have succeeded in quantifying the secretion in only six out of 1 3 species in which nectar is the main reward. These species were Daphne gnidium (0.17 mg sugar/ flower per 24 hr.). Erica ciliaris (0.08 mg), La- vandula stoechas (0.15 mg), Lonicera pericly- -1 1 2 3 # FLOWER DRY WEIGHT (log) ulmifolius maining seven species the yield of nectar sugar Figure 1. Relationship between the weight of an per flower per 24 hr. was too scarce to be quan- individual flower and the mean number of flowers per square meter in peak blooming plants. Triangles sprouting taxa; circles = nonsprouting taxa. (presumably Maximum tween 9.5% {Erica ciliaris) and 60% {Ruhus ul- mifolius)', volumes per flower on a daily basis Flower sizes (as dry weight of the complete flow- ranged between 0.9 ^1 {Lavandula stoechas, er) in the sample range between 2.2 mg for the Daphne gnidium) and 10 ^1 {Lonicera pericly- female flowers of Pistacia lentiscus and 65.5 mg menum). salvifolius Pollen yield of the individual flowers is given have flowers of 5 mg or less in dry weight. Floral in Table 1 . The lowest is that of Armeria velutina dry weight is not independent of the breeding Myrt system in this set of species. If taxa are segregated munis (599 x 1 0^), which has insect-pollinated, in two categories, less or more than 5 mg (a value nectarless flowers of the brush type common in that is near the median in the frequency distri- the Myrtaceae. Since pollen production is not bution), dioecious taxa predominate in the lower independent of flower size, a more correct esti- class (8 out of 9), whereas hermaphroditic taxa mate of staminate effort on a per flower basis are evenly distributed among the two classes (10 would be the number of pollen grains produced and 11, respectively). The differences are statis- per milligram of flower dry weight (Relative Sta- tically significant {G = 5.04, df - 1, P < 0.025). minate Effort, RSE). Defined in this way, RSE is The predominant flower morphology is of the minimum for entomophilous taxa such as Ar- type (Faegri meria velutina (500) and Lonicera periclymenum is present in the Cistaceae and also in all the (524). The former has dimorphic pollen grains entomophilous dioecious taxa. Species in the La- and stigmas, and the latter has the most spe- biatae have short, tubular corollas; while the le- tubed, highly gumes present typical flag blossoms. The only in the sample. Maximum values of RSE are found [lowers are those of Lonicera pericly- in anemophilous species such as Corema album tubed menum. Generally speaking, flowers are small (2.3 x \0^)zr\d Erica scoparia{\2Q x 10^). Mean and/or have corollas that impose little or no re- RSE is significantly higher for anemophilous taxa striction on floral visitors (except for L. pericly- than for entomophilous ones (t/ = 121, N = 5, menum and the legumes). All species in the Le- 25, P < 0.001). guminosae and three in the Cistaceae have yellow Values of pollen-ovule ratios for hermaphro- flowcrs, which is the most common color (nine ditic species are given in Table 1. In most taxa of total); whereas six species have white corollas, this ratio is greater than 2,000 and thus referable Many of these yellow- or white-flowered taxa to the allogamous class of Cruden (1977). Only offer pollen as the main reward to pollinators three species have pollen-ovule ratios lower than (Table 1). There are five species with pink flow- 1,000. Mean number of flowers for plants in peak ers, which provide predominantly nectar as the bloom are also shown in Table L A highly sig- reward. nificant relationship exists between flower num- 1987] HERRERA- FLOWER & FRUIT BIOLOGY 73 Table 2. Fruit and seed characteristics for 29 scrub species. Numbers in parentheses are sample sizes. Species Mean Number Type' of Seeds Mean Dry Weight (mg) Whole Fruit All Seeds Individual Seed Pre- dation Armeria velutina Asparagus aphyllus Calluna vulgaris Chamaerops humilis Cistus lihanotis Cistus salvifolius Corema album Cytisus grandiflorus Daphne gnidium Erica ciliaris Erica scoparia Halimium commutatum Halimium halimifolium Helianthemum croceum Helichrysum picardii Lavandula stoechas Lonicera periclymenum Myrtus communis Osyris alba Osyris quadripartita Phillyrea angustifolia Pislacia lentiscus Rhamnus lycioides Rosmarinus officinalis Rubus ulmifolius Smilax aspera Stauracanthus genistoides Ulex minor Ulex parvijlorus D F D F D D F D F D D D D D D D F F F F F F F D F F D D D 1 1.2 3.6 I 22.3 51 3 6.9 1 17.9 6.5 2.6 25.7 10.3 1 2.3 2.3 5.7 .6 2.9 40.4 1.4 2.5 2.1 2 3 46 2 1,364 59 137 57 214 18 5 1 33 59 34 0.6 4 52 108 157 131 35 22 63 4 213 78 59 22 47 50) 100) 100) 18) 20) 12) 30) 20) 75) 80) 60) 20) 20) 15) 750) 50) 30) 75) 30) 75) 100) 80) 30) 20) 30) 100) 15) 20) 10) 1 23 0.2 781 23 53 35 39 8 0.2 0.1 14 15 15 0.6 1 15 56 90 73 12 13 26 2 87 51 13 7 12 1 19 (50) (122) 0.1 (325) 781 1 1 12 6 8 (18) (445) (612) (90) (137) (75) 0.01 (1,150) 0.02(1,000) 6 (52) 0.6 (514) 1 (155) 0.6 (750) 0.6 (114) 7 10 90 73 12 13 16 (30) (430) (30) (75) (100) (80) (30) 0.6 (59) 2 36 5 3 6 (30) (140) (38) (35) (20) + + + + + + + + + + + + + + + + D, dry fruits; F, fleshy, vertebrate-ingested fruits. ber and flower size (dry weight); this relationship have fleshy fruits, while the latter have dry fruits can be easily appreciated in Figure 1 {r N 27, P < 0.001) 0.826, (mostly capsules, legumes, or achenes). Seed col- lecting by ants has been observed in a few taxa. Damage of flowers by insect predators, mostly but data are not conclusive enough to recognize noctuid larvae, coleopteran larvae, and other a third (ant-dispersed) class. Most vertebrate- unidentified insects, was observed in only four dispersed plant species in the sample have or- species (Table 1). FRUIT BIOLOGY nithochorous diaspores (C. M. Herrera, 1984a). Mean number of seeds per fruit ranges between 1 and 51, and the fruit size (fruit dry weight) Table 2 summarizes various characteristics of between 0.6 mg {Helichrysum picardii) and 1 ,364 the fruits in our set of mediterranean plant species. mg {Chamaerops humilis). The lightest seeds are Fruit production in Thymus tomentosus was so those of Erica ciliaris (2 x 10^ mg) and the sparse that we were unable to gather a reasonable heaviest those of Chamaerops humilis (78 1 mg). sample of fruits and seeds; this species has there- Predation of fruits, mainly by Curculionidac, lar- fore been excluded from the analyses. According vac of Tortricidae, Noctuidae, and parasitic hy- to the way in which their seeds are dispersed our menopterans, is far more common than flower taxa are easily divided in two groups: those whose predation (55% and 1 3% of species, respectively), seeds are dispersed by vertebrates (13 taxa) and Damage by predators was observed more fre- those whose seeds are dispersed by the wind or quently on dry than on fleshy fruits {G = 4.02, in a largely passive way (16 taxa). The former df = \, P < 0.05). 74 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 Table 3. Results of independence tests performed Erica scopaha, Myrtus communis, and Rosma- between the type offruit (dry or fleshy) and other vari- rinus officinalis), but even in such cases polli- ables of flowers and fruits. Class intervals considered nating vectors were needed for fruiting to arrive were weight offruit, less than 20 mg, 20-40 mg, 40- ^^ j|^ maximum 60 mg, or more than 60 mg; weight of the individual seed, less than 10 mg, or more than 10 mg; number of seeds per fruit, less than 2, 2-4, or more than 4. Independence of Fruit Type G df P Sexuality (hermaphrodit- ism, dioecy) Weight of fruit Weight of individual seed Seeds per fruit 11.72 8.04 23.32 13.85 1 3 1 2 < 0.001 <0.05 0.001 0.001 G, value of the statistic in the G test of independence; df, degrees of freedom. REPRODUCTIVE TRADE-OFFS Figure 2 shows the relationship between per- cent fruiting and the quotient of the fruit dry weight to the flower dry weight (fruit : flower size ratio hereafter), which indicates about how high the increase in size is from the first reproductive unit to the second. This variable will be em- ployed below to investigate some patterns of re- productive allocation in our set of species. A highly significant negative relationship exists be- tween percent fruit production and fruit : flower size ratio (r 0.6780, N = 26, P < 0.001, log transformed data). Thus species in which there Results of tests for the independence of fruit is a great increase in dry weight during the tran- type and a few variables of flowers and fruits are sition from flower to fruit are those with the low- given in Table 3. There is a significant tendency est percent fruiting, whereas species in which this for species with hermaphroditic flowers to pro- process involves little gain in weight have rela- duce dry fruits, and for species with unisexual lively greater fruiting success. flowers to produce fleshy fruits. The indepen- Species known to perform vegetative rcgcn- dence hypothesis offruit type and breeding sys- eration (sprouting) are distinguished from non- tem (Bawa, 1980) is thus rejected (Table 3). The sprouting ones in Table 4, and their respective only gynodioecioustaxon in the sample has been distribution in the relationship defined by per- included (conservatively) in the dioecious class cent fruit production and fruit: flower size ratio for this analysis. The independence hypothesis is shown in Figure 2. Sprouting taxa tend to have for the type offruit and the variables weight of low values of fruiting and high values of fruit: fruit, weight of an individual seed, and seeds per flower size ratio. Mean percent fruit production fruit are all rejected. In fact, fleshy fruits tend to is not, however, significantly different for sprout- be, on average, heavier than dry ones (t/= 185.5, ing and nonsprouting taxa {U = 109, N 14, N = 16, 13, P < 0.05) and to have fewer and 12, T' > 0.2); differences in mean dry weight heavier seeds {U = 203, N = 16, 13, F < 0.001). increase from flower to fruit are weakly signifi- Note that we are reporting dry weights, so that cant {U = 1 17.5, P > 0.05). Species in the Eri- differences are not due to the high water content caceae lower the coherence of the sprouting group, of fleshy, vertebrate-ingested fruits since they are well-known sprouters but have Fruiting intensities for 28 of the studied species relatively low fruit : flower size ratios. If the Er- can be seen in Table 4. Data are not available icaceae are removed, the sprouting group is en- for two dioecious species, Corema album and lirely composed of taxa with few-seeded, vcrtc- /?//amA2W5/vc/o/<^£'5. Fruit production after exclu- brate-ingested fruits; with the exclusion of sion of pollinators is also reported for hermaph- ericaceous taxa, the nonsprouting group overlaps roditic taxa. Percent of fruit production in open entirely with the dry fruit group, and the sprout- pollinated flowers ranged between 2% for Thy- inggroupdoeslikewise with the fleshy fruit group. mus tomentosus and Daphne gnidium, and 92% Differences in mean percent fruit production and for Halimium commutatum. Bagging of flowers fruit: flower size ratio are now significant (U = = 12, in most cases had a clear eflfect of decreasing fruit 101.5, P < 0.05; U = 1 16.5, P < 0.002, N production— to levels as low as 0-1% in 15 1 1, respectively). species. There was just one taxon that was un- Figure 1 shows an inverse relationship be- affected by exclusion of pollinators {Daphne gni- tween the number of flowers at peak blooming dium. 2% fruit production under both treat- and flower dry weight. Both sprouting and non- ments). Some fruit was produced (10-31%) in sprouting species are evenly distributed along this bagged flowers of a few taxa {Calluna vulgaris, continuum, so that mean number of flowers at 1987] HERRERA-FLOWER & FRUIT BIOLOGY 75 Table 4. Fruit production in open pollinated and bagged flowers of the studied species. Numbers in paren- theses indicate the number of flowers, and N the number of plants. The sample of the only gynodioecious species (Thymus tomentosus) includes three hermaphrodites and four female plants. Species known to be capable of sprouting are marked with an asterisk. Species Armeria velutina Asparagus aphyllus* Calluna vulgaris'^ Chamaerops humilis* Cistus libanotis Cistus salvifolius Cytisus grandijlorus Daphne gnidium* Erica ciliaris* Erica scoparia Halimium commutatum Halimium halimifolium Helianthemum croceum Helichrysum picardii Lavandula stoechas Lonicera periclymenum* Myrtus communis^ Osyris alba* Osyris quadripartita* Phillyrea angustifolia* Pistacia lentiscus* Rosmarinus officinalis Rubus ulmifolius* Smilax aspera* Stauracanthus genistoides Thymus tomentosus Ulex minor Ulex parvijlorus Fruit Production (%) Open Pollinated 59 24 88 4 55 50 12 2 45 89 92 41 68 69 8 68 7 5 14 16 31 78 9 40 2 16 5 Bagged 476) 50) 538) 92) 134) 2,660) 105) 65) 100) 1,259) 171) 1,443) 1 ,040) 211) 78) 735) 797) 158) 651) 210) 221) 471) N 5 6 5 7 4 10 4 10 10 5 5 5 3 5 10 4 4 8 5 5 5 5 10 5 4 7 10 5 peak blooming is not significantly different be- studied taxa are widespread, and the community tween them (f/= 101, /'> 0.1); neither is mean they form is undoubtedly a clear example of flower dry weight significantly different {U coastal scrub on sandy soils, which is character- 1 13.5, P > 0.1, N = 14, 13). Both sprouting and istic of other areas in southern Spain. nonsprouting taxa may be many- and small- or few- and big- flowered. Discussion In the studied community a sizeable hetero- geneity in reproductive traits was likely to occur, since 30 plant species were distributed among 1 7 families. However, certain groups (virtually Cis- taceae, Leguminosae, Ericaceae, and Labiatae) The 30 mediterranean plant species studied contributed with more taxa to the sample than represent a relatively small sample of the regional did others. Hence a phylogenetic component in flora (more than 2,000 taxa for southern Spain, the reproductive patterns recognized should not of which nearly 300 are woody). Furthermore, be ruled out, in addition to an ecological com- shrublands have many different and diverse ponent and to the fact that the plants form a species compositions in southern Spain, depend- steady, long-lasting community achieving repro- ing on elevation, rainfall, edaphic factors, etc., duction year after year. Several aspects in the so that the results reported here should be ex- reproductive patterns are not restricted to our tended only with caution to other scrub com- particular community. The relative dominance munilies in the region. Nevertheless many of the of taxa in which nectar yield is low or even 76 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 100 K50 A A A A a: u. A • • • - A A • • A A A 1 2 sin. In our community most plants fall clearly into one category or the other, although species in the Ericaceae could be easily included in both: they produce plenty of seeds and are also able to sprout, which was reported some time ago for Calluna vulgaris (Kayll & Gimingham, 1965). It has been hypothesized that pollination-re- production variables may be associated with each of the sprouting or nonsprouting strategies. In seeders, for example, the pollination system must be efficient enough to assure the release of nu- merous seeds (which could open a way to self- compatibility), produce numerous flowers highly attractive to pollinators, and offer a greater re- ceae. FRUIT WEIGHT: FLOWER WEIGHTdog) ward per flower than sprouters (Carpenter & Figure 2. Relationship between fruit: flower dry Recher, 1979). In contrast, sprouting taxa are weight ratio and percent fruiting for 26 scrub taxa. proposed to have a high rate of outcrossing, al- Triangles = sprouting species; circles = nonsprouting though often with a low production of flowers, species; black triangles = species in the family Erica- ^^ich would be relatively low rewarding (Fulton & Carpenter, 1979; Carpenter & Recher, 1979). These hypotheses are supported in part by our for example, is general in the region (J. Herrera, data. 1985). The consequences of this factor upon the A high rate of outcrossing has to be expected pollination relationships will be dealt with else- in the sprouting group of species, since many where (J. Herrera, in prep.). Dispersal by inan- dioecious taxa are included in that group. There imate or vertebrate agents creates a dichotomy are no evident signs, however, ofa high incidence that is also found in other mediterranean-type of self-pollination in the nonsprouting group. In communities (Bullock, 1978, chaparral; C. M. contrast, mean percent fruit production was sig- Herrera, 1984b; Jordano, 1984, southern Spain). nificantly higher for nonsprouters than for As has been reported in other woody commu- sprouting species, which confirms the hypothesis nities (Reader, 1977; Ruiz-Zapata & Arroyo, outlined above. Low pollination efficiency due 1978; Bawa, 1979; Bawa & Beach, 1983) polli- to unisexuality can be reasonably proposed to nators are needed for maximum fruit produc- explain low fruit production in the sprouting tion. Further investigations will determine the group, but we wish to put forward a comple- extent to which incompatibility systems occur in mentary view. Percent of fruit production was shrublands of southern Spain found to be inversely related to fruit : flower size Sprouting is also a common regenerative strat- ratio (i,e., the increase in mass needed to produce egy of woody plants in many and diverse eco- a fruit from a flower). Such a relationship sug- systems (James, 1984). It is particularly impor- gests the existence ofa trade-off* between the en- tant in regions ofa mediterranean-type climate ergy that a plant allocates to an individual fruit that experience summer droughts and frequent or seed and the number it can successfully form, fires. This aspect has received much attention in Low fruit production in vertebrate-dispersed, big- the Califomian chaparral (Wells, 1969; Keeley, seeded species may reflect low pollination suc- 1 977), where two general reproductive strategies cess and/or the impossibility of developing every (in fact, extremes of a continuum) have been fruit with pollinated ovules, due to the relatively recognized: the "seeder" strategy consists of ob- high costs involved in the ripening process. It ligate seed reproduction and incapacity to form has been demonstrated, for example, that some new stem sprouts after destruction of aerial parts; species experience low fruit production despite the "sprouters" can produce stem or root sprouts good levels of pollination, which is apparently that enable repeated shoot production despite due to intrinsic regulatory mechanisms (Lloyd, frequent damage (Malanson i& Westman, 1985; 1980;Wyatt, 1981; Casper & Wiens, 1981;Cas- see James, 1984, for an extensive review). It ap- per, 1983; Bookman, 1983; Bawa & Webb, 1984; pears that both strategies also are found among see Stephenson, 1981, for a review). Flower size sclerophyllous species of the Mediterranean Ba- and number showed a negative relationship too. 1987] HERRERA- FLOWER & FRUIT BIOLOGY 77 but the predicted tendency for sprouting taxa to Bolten, A. B., P. Feinsinger, H. G. Baker & L Baker. appear at one end of this continuum has not been detected by us. Wells (1969) pointed out that the capacity to sprout vegetatively from underground parts is probably an ancestral trait. James (1984), how- ever, suggested that sprouting cannot always be seen as an ancestral trait in woody dicotyledons. In the present study the capacity to sprout is associated with other traits, such as the produc- 1979. On the calculation of sugar concenlration in flower nectar. Oecologia (Berl.) 41: 301-304. Bookman, S. S. 1983. Costs and benefits of flower abscission and fruit abortion in Asclepias speciosa. Ecology 64: 264-273. Bullock, S. H. 1978. Plant abundance and distri- bution in relation to types of seed dispersal in chaparral. Madrofio 25: 104-105. Carpenter, F. L. & H. F. Recher. 1979. Pollination, reproduction and fire. Amer. Naturalist 1 13: 871- 879. and rates of embryo initiation in Cryptantha (Bo- raginaceae). Oecologia (Berl.) 59: 262-268. — & D. WiENS. 1981. Fixed rates of random tion of fleshy, vertebrate-ingested fruits, heavy Casper, B.B. 1983. The efficiency of pollen transfer seeds, and low fruit production, along with a relatively high incidence of dioecy (species in the genera Asparagus, Chamaerops, Lonicera, Osy- ris, Pistacia, Rhamnus and Smilax, for exam- ple). This group of taxa has subtropical affinities: sclerophyllous species in these genera existed well before the Pleistocene and the evolution of true mediterranean climatic conditions (Raven, 1973; Axelrod, 1975; Pons, 1981). In contrast, species in the genera Armeria, Cisius, Cytisus, Hali- mium, Lavandula, Rosmarinus, or Thymus are nonsprouters; and the high number of taxa en- ovule abortion in Cryptantha flava (Boraginaceae) and its possible relation to seed dispersal. Ecology 62: 866-869. Cody, M. L. & H. A. Mooney. 1978. Convergence versus non-convergence in mediterranean-climate ecosystems. Ann. Rev. EcoL Syst. 9: 265-321. Cruden, R. W. 1977. Pollen-ovule ratios: a conser- vative indicator of breeding systems in flowering plants. Evolution 31: 32-46. Faegri, K. & L. van der Pul. 1979. Principles of Pollination Ecology, 3rd edition. Pergamon Press, Oxford. demic to the Mediterranean Basin makes clear Frankie, G. W., H. G. Baker & P. A. Opler. 1974. that species in these genera originated much more recently (Quezel, 1978, 1981; Pons, 1981). The capacity to sprout is thus lacking in the typically mediterranean taxa but is present in the more ancient, pre-mediterranean ones. This supports the view of Wells (1969) that sprouting is an ancestral trait, and it may indicate that only those ^'tertiary flora" subtropical sclerophyllous taxa with a capacity to sprout were able to survive the shift to seasonal dryness associated with the mediterranean climate. Comparative phenological studies in tropical wet and dry forests in the lowlands of Costa Rica. J. Ecol. 62: 881-919. — , W. A. Haber, p. a. Opler & K. S. Bawa. Literature Cited 1 983. Characteristics and organization of the large bee pollination system in the Costa Rican dry for- est. Pp. 411-447 in C. E. Jones & R. J. Little (editors), Handbook of Experimental Pollination Biology. Scientific & Academic Editions, New York, Fulton, R. E. & F. L. Carpenter. 1979. Pollination, reproduction and fire in California Arctostaphylos. Oecologia (Berl.) 38: 147-157. Heithaus, E. R. 1974. The role of plant-pollinator interactions in determining community structure. Ann. N4issouri Bot. Gard. 61: 657-691. Allier, C. F., F. Gonzalez-Bernaldez & L. Ra- Herrera, CM. 1981. Are tropical fruits more re- MiREZ-DiAZ. 1974. Reserva Biologica de Doii- ana. Ecological Map. Estacion Biologica de Don- ana, CSIC, Sevilla, Spain. Axelrod, D. L 1975. Evolution and biogeography of the Madrean-Tethyan sclerophyll vegetation. Ann. Missouri Bot. Gard. 62: 284-334. Bawa, K. S. 1979. Breeding systems of trees in a tropical wet forest. New Zealand J. Bot. 17:521- 524. . 1 980. Evolution of dioecy in flowering plants. Ann. Rev. Ecol. Syst. 11:15-39. & J. H. Beach. 1983. Self-incompatibility warding to dispersers than temperate ones? Amer. Naturalist 118: 896-907. — . 1984a. A study of avian frugivores, bird- dispersed plants and their interactions in medi- terranean scrublands. Ecol. Monogr. 54: 1-23. — . 1984b. Patrones morfologicos y funcionales systems in the Rubiaceae of a tropical lowland wet forest. Amer. J. Bot. 70: 1281-1288. — & P. A. Opler. 1975. Dioecism in tropical forest trees. Evolution 29: 167-179. — & C. J. Webb. 1984. Flower, fruit and seed abortion in tropical forest trees: implications for the evolution of paternal and maternal reproduc- tive patterns. Amer. J. Bot. 71: 736-751. en plantas del matorral mediterraneo del sur de Espana. Studia Oecologica 5: 7-34. Herrera, J. 1 985. Nectar secretion patterns in south- em Spanish mediterranean scrublands. Israel J. Bot. 34: 47-58. Inouye, D. W., N. D. Favre, J. A. Lanum, D. M. Levine, J. B. Meyers, M. S. Roberts, F. C. Tsao & Y. Y. Wang. 1980. The effect of nonsugar nectar constituents on estimates of nectar energy content. Ecology 61: 992-995. James, S. 1984. Lignotubers and burls— their struc- ture, function and ecological significance in med- iterranean ecosystems. Bot. Rev. 50: 225-266. Jordano, p. 1982. Migrant birds are the main seed 78 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 ofblackberries 38: 183-193. Kayll — . 1984. Relaciones entre plantas y aves frugi- voras en el matorral medilerraneo del area de Donana. Ph.D. Thesis. University of Sevilla, Se- villa, Spain. A. J. & C. H. GiMiNGHAM. 1965. Vegetative regeneration of Calluna vulgaris after fire. J. Ecol. 53: 729-734. systems. Biotropica (Tropical Succession) 12: 40- 46. PojAR, J. 1974. Reproductive dynamics of four plant communities of southwestern British Columbia. Can. J. BoL 52: 1819-1834, Pons, A. 1981. The history of the mediterranean shrublands. Pp. 131-138 in F. di Castri, D. W. Goodall & R. L. Specht (editors), Mediterranean- type Ecosystems. Elsevier, Amsterdam. Keeley 1977. Seed production, seed popula- Primack, R. B. 1983. Insect pollination in the New tions in soil and seedling production after fire for two congeneric pairs of sprouting and non-sprout- Kevan 820-829 n of high flowers. J. Ecol. 60: 831-847. Kruger, F. J growth Zealand mountain flora. New Zealand 317-333. ZEL, P. 1978. Analysis of the flora of the Medi- terranean and Saharan Africa. Ann. Missouri Bot. Gard. 65: 479-534. . 1981. Floristic composition and phytosocio- rhythms: South African heathlands. Pp. 1-4 in R. L. Specht (editor). Ecosystems of the World. Heathlands and Related Shrublands. Elsevier, Amsterdam. logical structure of sclerophyllous matorral around the Mediterranean. Pp. 107-121 in F. di Castri, D. W. Goodall & R. L. Specht (editors), Mediter- ranean-type Ecosystems. Elsevier, Amsterdam. KuMMEROV, J. 1983. Comparative phenology of Raven mediterranean-type plant communities. Pp. 300- 317 in F. J. Kruger, D. T. Mitchell & J. U. M. Jarvis (editors), Mediterranean-type Ecosystems. Springer- Verlag, Berlin. Lloyd, D. G. 1980. Sexual strategies in plants. I. A hypothesis of serial adjustment of maternal in- vestment during one reproductive session. New Phytol. 86: 69-79. Malanson 1985. Post fire floras. Pp. 2 1 3-224 in F. di Castri & H. A. Mooney (editors), Mediterranean-type Ecosystems. Spring- er- Verlag, Berlin. Reader, R. J. 1977. Bog ericads flowers: self-com- patibility and relative attractiveness to bees. Can. J. Bot. 55: 2279-2287. Rivas-Martinez, S., M. Costa, S. Castroviejo & E. Valdes. 1980. Vegetacion de Donana (Huelva, Esoanay Lazaroa 2: 5-189. succession in California coastal sage scrub: the role Ruiz-Zapata, T. & M. T. K. Arroyo. 1978. Plant of continual basal sprouting. Amer. Midi. Nat. 113: 309-318. Moldenke 1975. Niche specialization and species diversity along a California transect. Oeco- logia(Beri.)2l: 219-242. Mooney 1970. Convergent reproductive ecology of a secondary deciduous forest in Venezuela. Biotropica 10: 221-230. Specht, R. L. 1969. A comparison of the sclero- phyllous vegetation characteristics of mediterra- nean type climates in France, California, and southern Australia. Austral. J. Bot. 17: 277-292. evolution of mediterranean-climate evergreen sclerophyll shrubs. Evolution 24: 292-303. &D. J. Parsons. 1973. Structure and function . Rodgers growth an< 1981 of the California chaparral. Pp. 83-112 in F. di Castri & H. A. Mooney (editors), Mediterranean- type Ecosystems. Springer- Verlag, New York. — , & J. KuMMEROv. 1974. Plant devel- opment in mediterranean climates. Pp. 255-267 in H. Lieth (editor). Phenology and Seasonality Modeling. Springer- Verlag, New York. MosQUiN, T. 1971. Competition for pollinators as a stimulus for the evolution of flowering times. Oi- kos 22: 398-402. Opler, P. A., H. G. Baker & G. W. Frankie. 1980. Plant reproductive characteristics during second- ary succession in neotropical lowland forest eco- lian heathlands. Pp. 5-13 in R. L. Specht (editor). Ecosystems of the World. Heathlands and Related Shrublands. Elsevier, Amsterdam. Stephenson, A. G. 1981. Flower and fruit abortion: proximate causes and ultimate functions. Ann . Rev. Ecol. Syst. 12: 253-279. Wells, P. V. 1969. The relation between mode of reproduction and extent of speciation in woody genera of the California chaparral. Evolution 23: 264-267. Wyatt, R. 1981. The reproductive biology ofAscle- pias tuberosa II: factors determining fruit set. New Phytol. 88: 375-385. REPRODUCTIVE SYSTEMS AND CHROMOSOME RACES OF OXALIS PES-CAPRAE L. AND THEIR BEARING ON THE GENESIS OF A NOXIOUS WEED 1 Robert Ornduff^ Abstract In its native South Africa, Oxalis pes-caprae is represented by diploid and tetraploid races; the short-styled, sterile pentaploid race reported as a noxious weed elsewhere is apparently uncommon there. South African plants have trimorphic flowers, but the three morphs usually are not present in equal proportions in natural populations. The diploid and tetraploid races of the species have a well- developed incompatibility system associated with their floral trimorphism. Outside South Africa, the species is represented not only be a fairly sterile short-styled pentaploid, but sexual tetraploids are known as well. Although the latter may have resulted from independent introductions, low levels of sexuality in the pentaploids also could account for the origin of tetraploidy in situ as a consequence of the union of diploid gametes, and may account for the occasional spontaneous appearance of mid- styled plants in populations of the short-styled pentaploid. Pentaploidy hkely resulted from the union of an unreduced gamete of a tetraploid with a haploid gamete of a diploid and presumably developed in South Africa. Since weediness is characteristic of many populations of the native diploids and tetraploids in South Africa, pentaploidy per se cannot be implicated in the origin of weediness, nor is there evidence of any aggressive superiority of the short-styled morph in the sexual races in South Africa. Why the pentaploid is such a successful weed outside South Africa, but apparently less successful as a weed than the diploids and tetraploids within South Africa, is unknown. Oxalis pes-caprae L. is a troublesome and and chromosome cytology of plants originating widespread agricultural and garden weed, par- in South Africa were studied in the hopes of elu- ticularly in areas of the world with a mediter- cidating the events that led to the origin of the ranean climate such as central Chile, the Medi- aggressive weedy races from the native races. Materials and Methods Bulbs collected from natural populations of terranean basin, parts of Australia, and California (Salter, 1944; Young, 1958; Munz, 1959; Mi- chael, 1964). The species is native to southern Africa, where it is variable (Salter, 1944), and Oxalis pes-caprae in the Cape Province region where it is distributed from Namibia (South West in South Africa in 1 970 and 1 97 1 were later grown Africa) southward to the Cape region and around at Berkeley for chromosome studies. One col- the Indian Ocean coast at least as far north as lection was provided by Sherwin Carlquist. the Knysna area, sometimes ranging well inland. Chromosome numbers were determined by ex- There it occurs as a "well-behaved" native of amining microsporogenesis in flower buds of relatively undisturbed sites as well as a weed, these cultivated plants preserved in 3 : 1 elhanol : and it is particularly common in vineyards and acetic acid and stained in acetocarmine. Bulbs along roadsides. In southern Africa, the species collected by Peter Goldblatt from two localities is tristylous (Fig. 1), but throughout most of its in 1984 provided plants used in an artificial exotic range it is represented by a short-styled crossing program to determine the presence and form, which is pentaploid {2n = 35), and which nature of an incompatibility system in this tri- reproduces asexually via bulbils. In parts of its stylous species. These localities are an aban- exotic range, tetraploid and presumably sexual doned farm near Noordhoek, Cape Peninsula, populations also occur, though less commonly and a vineyard at Rustenberg, near Stellenbosch, than the sterile pentaploid. Cape Province. The two localities are ca. 50 km In view of the importance of this species as a from each other. Crosses were made in the spring weed, certain features of the reproductive biology of 1985 and 1986 by transferring pollen from ' Supported in part by grants from the National Science Foundation, the Council for Scientific and Industrial Research of South Africa, and the Committee on Research, University of California, Berkeley. I thank Sherwin Carlquist, T. I. Chuang, Rivka Dulberger, Peter Goldblatt, R. Harry Koga, Peter W. Michael, Donald Pfister, Kim E. Stciner, David E. Symon, and Patricia Walters for assisting this study in various ways. ^ Department of Botany, University of California, Berkeley, California 94720. Ann. Missouri Bot. Gard. 74: 79-84. 1987. 80 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 lO long -level mid-level short-level Long Mid Short Figure 1. Illustrations of gynoecia and androecia of the three floral forms of Oxalis pes-caprae. The des- ignation of each floral form is given below each illustration. The stigma and anther level designations used in the text are given to the right of the figure. dehisced anthers to stigmas under insect-free tions, morph ratios of Longs :Mids: Shorts were conditions. Seed set was determined by collect- 1:1:1, both populations were considered, with ing nearly mature capsules and counting the seeds some doubt, to be non-weedy. In four popula- released by them in seed packets. Pollen size for tions, morph ratios deviated from equality. In the three morphs was determined by mounting one of these, Longs were deficient; in another, fresh grains in aniline blue-lactophenol and mea- Mids; in third, Shorts; and in the fourth. Longs suring them with an ocular micrometer; pollen and Mids were greatly outnumbered by Shorts, stainability was determined by counting the Three of these four populations were character- number of stained grains in a sample of 100 ized as weedy (two for which chromosome counts mounted in this medium. Results are available were tetraploid). Pollen size and stainability. Pollen si/e of diploids and tetraploids is trimorphic (Table 1). Chromosome numbers. Seven of the nine na- Pollen from the long-level anthers is largest, that tive populations examined were tetraploid {n from mid-level anthers is smaller, and that from 1 4); two were diploid (n = 7; Table 1). Previously short-level anthers is smallest. Pollen from an- published reports, summarized in Table 2, in- thers at equivalent levels in different morphs was dicate only tetraploidy and pentaploidy for the generally of the same size within a population, species. Weedi but there were interpopulation diflferences in pol- The two diploid populations and len size from equivalent anther sets. There was four of the tetraploid populations were growing no correlation between diflferences in pollen size under disturbed conditions such as roadsides, and in chromosome number of the diploids and vineyards, or grainfields and were considered tetraploids. Pollen from presumed pentaploids weedy; the others occurred in undisturbed con- collected in California was extremely variable in ditions and were considered non-weedy (field data size, even from an individual anther. Pollen are lacking for one tetraploid population; Table stainability of diploids and tetraploids was vari- 1). Morph Morph able, but was mostly over 60%. One Short tet- raploid {7038. Table 1) had pollen with 1 2% and ported earlier (OmduflT, 1974). In two popula- 25% stainability from its two sets of anthers. One 1987] ORNDUFF-OA'-IL/.S' PES-CAPRAE 81 Table 1. Chromosome num bers, pollen size (Mm), and pollen stainability in Oxalis pes-caprae. Collection (author's Chromo- some Number • Moral Morph (size; standari Origin of Pollen d deviation; stainabil Mid-level Anthers ity in percent) or collector's field number) Long-level Anthers Short-level Anthers Cape Province, South Africa 7035: Worcester, river- bank, non-weedy n - 14 Long Mid 45.7; 2.65 ( ) 41.7; 1.83 ( ) 35.8; 2.03 ( ) 33.0; 2.05 ( ) 7038: Klapmuts, road- side, weedy n - 14 Short 54.1; 3.94 (12%) 41.2; 3.10 (25%) 7041: Stellenbosch, vineyard, weedy Short 49.5; 3.20 (66%) 41.8; 1.83(69%) 7096: Mamre Road Sta- tion, roadside, weedy n - 7 Mid 46.4; 1.95(99%) 33.7; 1.91 (98%) 7248: Gouda/Hermon, roadside, weedy n - 7 Mid 42.7; 3.94 ( ) 31.1;2.20( ) 7292: Hopefield/Mal- mesbury, field, non- weedv Long Mid Short 50.1; 2.38 (86%) 50.4; 4.15 (93%) 41.8; 1.83(89%) 41.5; 2.93 (98%) 42.7; 4.84 (88%) 38.9; 1.83 (78%) 7301: Hopefield/I ange- baan, field, non- weedy n = = 14 Long Mid Short 46.2; 1.68(83%) 48.3; 5.73 (81%) 39.0; 1.83(78%) 34.4; 2.03 (77%) 30.3; 3.92 (79%) 31.2; 1.54(81%) 8053: Calvinia, grain field, weedy n -- = 14 Long Mid Short 52.2; 2.67 (64%) 47.2; 2.75 (74%) 42.6; 2.42 (65%) 38.0; 2.55 (73%) 36.2; 2.52 (60%) 35.0; 1.81 (40%) 8055: Clanwilliam, veld, non-weedy Long Mid Short 45.1; 2.89 (94%) 48.3; 2.87 (88%) 38.2; 2.49 (75%) 38.8; 2.83 (82%) 32.6; 2.07 (68%) 32.6; 2.30 (86%) Goldblatt s.n.: Rustenberg, near Stellenbosch, abandoned farmland n = - 14 Long Mid Short ; (66%) -; - (70%) -; - (90%) -;- (81%) -; - (84%) -; - (62%) Goldblatt s.n.: Noordhock, n = \4 Cape Peninsula (81%) (88%) Carlquist s.n.: South- western Cape Prov- ince California, U.S.A.: Orndufl^5.^7.: Univ. California campus, Berkeley R. Dulberger s.n.: as above R. Dulberger s.n.: Col- lege Ave., Berkeley n 14 Long Mid -; - Short — ; — Long Mid 50.8; 4.84 (92%) Short 49.7; 4.37 (67%) (93%) (88%) (79%) -; - (78%) 40.2; 2.46 (80%) 32.0; L93(46%) 34.5; 2.01 (96%) 41.8; 3.71 (63%) Short Short (62%) (58%) (87%) (51%) Mid (49%) (58%) Mid (32%) (29%) set of anthers of a few other collections (e.g., 8053 ranging from 29% to 87%. However, these pollen Mid, Carlquist s.n. Long) had pollen with low grains were variable in size, and the total number stainability. The two collections used in the per anther was reduced compared with pollen crossing program had pollen stainabililics ex- production of diploids and tetraploids as esti- ceeding 62%. Presumed Short pentaploids col- mated from the density of the pollen grains on lected in California had pollen stainabilities the prepared slides. 82 ANNALS OF THE MISSOURI BOTANICAL GARDEN (Vol. 74 Table 2. Published chromosome counts of Oxalis pes-caprae Chromosome Number Locality of Population Examined 2n = 28 2n = 34 2n = ca. 35 2n = 35 Cape Town, South Africa India (garden plants) Madeira South Australia Western Australia India (Punjab) Italy Unknown South Australia Western Australia Cape Town, South Africa Reference Marks, 1956 Mathew, 1958 Borgen, 1974 Oram in Symon, 1961 Michael, 1964 BirandSidhu, 1978, 1979, 1980 Sidhu, 1979 Vignoli, 1935, 1937 Yamashita, 1935 Oram in Symon, 1961 Franklin in Michael, 1964 Franklin in Michael, 1964 Compatibility relationships. Table 3 presents rph summarized results for various crosses using par- be more common in weedy South African races ent plants from Rustenberg and Noordhoek. Le- than in non-weedy ones and are likely a conse- gitimate pollinations are those between anthers quence of vegetative propagation that is cn- and stigmas at equivalent levels; all other pel- hanced by physical disturbances of the habitat 1877). during agricultural or road-building activities. ►arwin Only 4% of the illegitimately pollinated flowers Morph ratios were found in which Longs, Mids, produced capsules compared with 87% of the and Shorts, respectively, were deficient in num- legitimately pollinated flowers. The average bers. Each unequal morph ratio differed from the number of seeds per pollination obtained from legitimate crosses was 1 5.9; from illegitimate ones 0-0 Intcrmorph 10-0.5 seeds termorph, legitimate pollinations produced 13.0- others, with no morph(s) predominating overall. Thus there is no basis from observation of native races that accounts for the fact that the aggressive morph outside South Africa is short-styled. Over most of its exotic range of distribution, Oxalis nps-canrac annears to be reoresented bv 20.9 seeds per pollination. The two populations a fairly sterile, pentaploid short-styled morph. used in the crossing program produced similar As early as 1887, Hildebrand noted the preva- results for all classes of crosses. Seed production lence of this short-styled form and its lack of seed of Shorts following legitimate pollinations was set. Henslow (1891, 1910) also noted these fca- slightly greater than that ofthe other two morphs. tares and described in some detail the means of Both populations are tetraploid (Table 1). Discussion vegetative reproduction later amplified by Galil (1968). Where introduced, the species is distrib- uted by human agents and, in places, by other In its native range in South Africa, Oxalis pes- animals such as the mole-rat (Galil, 1967) or by caprae is represented by indigenous weedy and birds (Young, 1958). non-weedy races with a conventional tristylous Despite the high level of pollen sterility ofthe floral morphology, including pollen-size tri- short-styled pentaploid, it apparently reproduces morphism, and a fully developed trimorphic in- occasionally by seed. This may result from self- compatibility system. Individuals are strongly or geitonogamous poUinalions in populations self-incompatible and illegitimate cross-polli- where Shorts alone are represented. Illegitimate nations produce little or no seed. Legitimate pol- pollinations of sexual Shorts carried out in the linations produce considerable quantities of seed. present study produced small amounts of seed. The pentaploid form has been reported from that which oflTers support for this suggestion. Vignoli country as well (Michael, 1964), but it is unclear (1937), in an embryological study ofthe species, how common this race is there. noted rare sexual reproduction in the pentaploid In South Africa, tetraploids are apparently more but concluded also that apogamy may rarely oc- common than diploids, but weedy populations cur in this race. Another line of evidence for 1987] OR N DUFF- OXALIS PES-CAPRAE 83 Table 3. Results of legitimate and illegitimate pollinations in two populations of Oxalis pes-caprae. The first figures summarize results for the Rustenberg population; the second figures summarize results for the Noordhoek population. Style Length (5 parent) x Anther Level/Style Length {$ parent)' Number of Flowers Pollinated Self-pollinations (all illegitimate): L X m/L selfed L X s/L selfed M X 1/M selfed M X s/M selfed S X 1/S selfed S X m/S selfed 18; 55 20; 12 38; 33 23; 35 18; 20 15; 12 Intermorph, illegitimate pollinations: L X s/M L X m/S M X s/L M X l/S S X 1/M S X m/L 26; 20 23; 13 25; 29 15; 26 15; 21 25; 30 Intermorph, legitimate pollinations: L X 1/M L X 1/S M X m/L M X m/S S X s/L S X s/M 18; 48 27; 34 33; 37 54; 42 13; 22 11; 29 Number of Flowers Producing Capsules 0;6 0;0 0;1 0;0 i;0 0;0 0;0 i;2 0;2 0;1 0;3 1:4 12;41 23; 30 29; 38 46; 34 11; 20 11;25 Summary of all legitimate, illegitimate pollinations: Legitimate Illegitimate 156; 212 261; 306 132; 188 3; 19 Number of Seeds Obtained 0;34 0;0 0;5 0;0 1;0 0;0 0;0 10; 7 0;8 0;1 0;9 17; 6 279; 738 430; 583 413; 533 797; 546 222; 460 255; 588 2,396; 3,448 28; 70 Average Number of Seeds/ Pollination ;0.6 0.2 1;0 0;0 0;0 0.4; 0.5 0;0.3 0;0 0:0.4 0.7; 0.2 15.5 15.9 12.5 14.8 17.1 ; 15.4 17.2 14.4 13.0 20.9 23.2; 20.1 15.4; 16.3 0.1;0.2 ' Notation is as follows: "L x m/L selfed" means a long-styled flower (L) was self-pollinated with its own pollen from the mid-level (m) set of anthers. "L x s/M" means a long-styled flower was pollinated with pollen from the short-level stamens of a mid-styled flower. Figure 1 illustrates the three flower types. occasional sexual reproduction of this form comes it is unknown whether these are composed of from the spontaneous appearance of Mids in oth- more than one morph. erwise short-styled populations as noted in Although the occurrence of tetraploids and southern Italy by Vignoli (1935) and in central peniaploids in Australia as a consequence of in- Califomia by Dulberger (pers. comm.). It also dependent introductions is documented (Mi- has been suggested that in Western Australia, chad, 1964), it is possible to explain the origin where the pentaploid sometimes exists in mixed of tetraploids within pentaploid populations by populations with tetraploids, hybridization be- another mechanism. The peniaploids produce tween the two may occur (Michael, 1964). The some viable pollen (Tabic 1; Vignoli, 1937; Bir variability of the species there would suggest fre- & Sidhu, 1 980; Michael, 1 964). The illustrations quent sexual reproduction (Peirce, 1973). Tet- and discussion of microsporogenesis in penta- raploid populations with all three style lengths ploids by Vignoli (1935, 1937) indicate that pol- are known in South Australia (Symon, 1 96 1) and len grains with n = 14 can be produced by such Western Australia (Michael, 1964) and these pre- plants. If megasporogenesis also results in eggs sumably reproduce sexually as well as asexually. with n = 14, fertilization of these eggs by diploid Tetraploids also have been reported from India sperm would result in a tetraploid zygote. and Madeira (Mathew, 1958; Borgen, 1974), but The place and mode of origin of the weedy 84 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 pentaploid race are uncertain. Lower ( 1 963) sug- Literature Cited gested that it may have originated outside South Bir, S. S. & M. Sidhu. 1978. In lOPB chromosome Africa. A 5x chromosome count reported by Mi- chael (1964) indicates that this race is present in South Africa, but it is apparently not common (although this remains to be documented). The origin of the weedy pentaploid race can only ten- tatively be reconstructed, but I believe that it likely occurred in South Africa, The simplest ex- planation for the origin of pentaploidy is that it number reports LX. Taxon 27: 223-231. weed of orchards of Paliala district, Punjab. Recent Res. PL Sci. (New Dehli) 7: 261-271. & . 1980. Cyto-palynological studies on weed flora of cultivable lands of Patiala district, Punjab. J. Palynology 16: 85-105. BoRGEN, L. 1974. Chromosome numbers of Maca- ronesian flowering plants II. Norwegian J. Bot. 2 1 : 195-210. resulted from the union of an unreduced gamete Darwin, C. 1877. The Diflcrent Forms of Flowers of a tetraploid plant with a haploid gamete from Lon don. Gaul, J. 1967. On the dispersal of the bulbs of Oxalis cernua Thunb. by mole-rats {Spalax eh- renhergi Nehring). J. Ecol. 55: 787-792. . 1968. Vegetative dispersal in Oxalis cernua. a diploid plant. Since diploids are unknown out- side South Africa, this event must be assumed to have occurred in South Africa. Although dip- loids and tetraploids are not known to be sym- patric in South Africa, they have been collected very near each other, so sympatry may occur. Weediness clearly preceded the occurrence of pentaploidy since sexual diploids and tetraploids are frequently aggressively weedy: they com- monly occur in cultivated fields and along road- sides. Pentaploidy itself has not conferred weedi- ness on the species. Likewise, prodigious means Lower, H. F. 1963. Report on Oxalis pes-caprae L. Amer. J. Bot. 55: 68-73. Henslow, G. 1891. On the northern distribution of Oxalis cernua Thunb. Proc. Linnean Soc. Lond. 1890-1891: 31-36. . 1910. Remarkable instances of plant disper- sion. J. Roy. Hort. Soc. 35: 342-361. HiLDEBRAND, F. 1887. Experimcnte iiber die gc- schlechtliche Fortpflanzungsweise der Oxalisar- Zeit in South Africa. Unpublished document supplied by Waite Institute, Glen Osmond, South Austra- lia. Marks, G. E. 1956. Chromosome numbers in the genus Oxalis. New Phytol. 55: 120-129. Mathew, p. M. 1958. Cytology of Oxalidaceae. Cy- tologia23: 200-210. Michael, P. W. 1964. The identity and origin of varieties of Oxalis pes-caprae L. naturalized in Australia. Trans. Roy. Soc. S. Austr. 88: 167-173. of vegetative reproduction occur in diploids and tetraploids with a fully developed sexual appa- ratus, so that the almost exclusively vegetative propagation characteristic of the pentaploid is a condition that likewise preceded the origin of pentaploidy. Present evidence, although scanty, suggests that the largely sterile pentaploid race is less success- ful as a weed in South Africa than are the sexual munz,"p. A. 1959. A California Rora. Univ. of Cal- ifornia Press, Berkeley and Los Angeles. Ornduff, R. 1974. Heterostyly in South African plants: a conspectus. J. South African Bot. 40: 169- 187 success over sexual races under exotic conditions p^jrce, J. R. 1973. Soursob {Oxalis pes-caprae L) (as, for example, seems to be the case in Austra- in Western Australia: its life history, distribution, morphological variation, and weed potential. Dept. Agriculture, W. Australia Technical Bull. 20: 1-9. Salter, T. M. 1944. The genus Oxalis in South Af- rica. J. South African Bot. (Suppl.) 1: 1-355. Sidhu, M. K. 1979. Distributional and Cytological Studies of the Weed Flora of Cultivable Fields of Patiala District, Punjab. Ph.D, Thesis, Patiala. Symon, D. E. 1 96 1 . The species of Oxalis established in South Australia. Trans. Royal Soc. S. Aust. 84: 71-77. ViGNOLi, L. 1935, Ricerche preliminari di citologia ^\i\V Oxalis cernua Thunb. NuovoGiom. Bot. Ital. diploids and tetraploids. Outside South Africa, however, the pentaploid seems to prevail, pos- sibly as a consequence of its greater competitive lia) or as a consequence of a series of coincidences of introduction that led to this race being more abundant than its apparent diploid and tetra- ploid precursors. There is a possibility that there are competitive differences among the chromo- somal races of Oxalis pes-caprae, or among its morphs (as suggested by Peirce, 1973). The re- duced pollen stainability of some field collections suggests the possibility that, in these, the sexual apparatus may be impaired and that asexual mechanisms are more important in their repro- ductive mode. Both suggestions merit study. 42: 668-669. 1937. Fenomeni reproduttivi di Oxalis cer- La Nevertheless, the sequence of events leading to Yamashita,K. 1935. Zytologische Studien an Oxafc the origin of pentaploidy and the routes of hu- I. Jap. J. Genet. 11: 36. man-aided migration and introduction of this Young, D. P. 1958. Oxafo in the British Isles. Wat- species to other continents will probably never soma 4: 51-69. be fully reconstructed. FLORA OF THE VENEZUELAN GUAYANA-II Julian A. Steyermark I Abstract A lolal of 1 8 species, four subspecies, and one variety are newly described from the Venezuelan Guayana, nearly one-half of Ihem originating from Cerro Marahuaca of Territorio Federal Amazonas, while the others are from Cerro de la Neblina, Guaiquinima, Huachamacari, Auyan-tepui, Ptari-tepui, and Sipapo. The following new taxa are included: Brocchinia oliva-estevae {BromQ\i2iCC2iQ)\ Peperomia gentryi, P. marahuacensis, and Piper gentryi (Piperaceae); Euphronia acuminatissima (Vochysiaceae); Ilex Uesneri (Aquifoliaceae); Sauvagesia marahuacensis, S. guianensis subsp. sipapoensis and subsp. guaiquinimensis (Ochnaceae); Bonnetia bolivarensis, B. guaiquinimae. B. ptariensis, and B. tristyla subsp. nervosa (Theaceae); Lissocarpa stenocarpa (Lissocarpaceae); Chomelia siergiosii, Coccocypselum croatii, Pagameopsis maguirei subsp. neblinensis var. pirapucuensis and subsp. pusillus, Psychotria guanchezii and P. ronaldii, Schradera marahuacensis, and Sipanea setacea (Rubiaceae); and Gongy- lolepis terramarae (Compositae). A reevaluation of Euphronia gives evidence for the maintenance of three species, instead of one as previously treated by Lleras, and provides a key to the known species. A study of the variation in Sauvagesia guianensis (Ochnaceae) reveals the occurrence of five mor- phologically closely related but geographically separated subspecies isolated on different sandstone table mountains. A key to the subspecies and the newly described Sauvagesia marahuacensis is provided, as well as a key to the newly described species of Bonnetia. Bromeliaceae Brocchinia oiiva-estevae Steyerm. & Lyman B. Smith, sp. nov. type; Venezuela. Bolivar: not contracted at base, the larger ones ligulate- lanccolate, acute, mucronate, 10 cm long, 1.7- 1 .8 cm wide, lower leaves ovale, acuminate, 1.5- summit of Auyan-tepui, extreme north end ^-^ ^"^ '«"S, 1-1.4 cm wide, the upper ones Ion- above Angel Falls, Dec. 1984, Francisco ^^' ^^^"^ ^^^ intemodes, minutely pale lepidote. Oliva Esteva s. n. (holotype, VEN). Figure 1 . ^^^^^ f"^'°'^' '^^P^ ^'"^^^^ lanceolate-ligulate, 6- 8 cm long, 1.4-1,7 cm wide. Inflorescence erect, Planta parva caulescens florifera 3.7 dm alta, caule laxly bipinnately paniculate, 2.1 dm long; rachis erecto folioso 13 cm alto; foliorum laminis majoribus slender, covered with a scattered brown furfura- ligulato-lanceolatisacutismucronatis 10 cm longis, 1.7- . . ^ -^v. c \^ ^ i . i 1.8cmIatis,inferioribusovatisacuminatis 1.5-2.8 cm ^^^^' mdument, with 5 short, racemose, lateral longis, 1-1.4 cm latis, ca. 10-nervatis, nervis paullo ^^^^ 3.5-6 cm long, each axis 15-17-flowered, obscuris; scapo folioso, scapi bracieis lanceolato-ligu- the uppermost part of the inflorescence elongated latuis 6-8 cm longis, 1.4-1.7 cm latis; inflorescentia to 10 cm; primary bracts subtending the lower three axes ascending, lanceolate, acute, 3 cm long. erecta laxe bipinnatim paniculata 2.1 dm longa tenui, rhachidi sparsim brunneo-furfuracea obtecta, axibus „ „ . . r, , i lateralibus gracillimis racemosis brevibus 3.5-6 cm 0.8 cm wide, entire; floral bracts lanceolate, acute longis, quoque axe 15-17-flora; bracteis primariis ad to acuminate, 3-3.5 mm long, 0.7 mm wide at 3 cm longis, 0.8 cm latis; bracteis florigeris lanceolatis the base. Flowers shortly pedicellate, pedicels 1- acutis vel acuminatis 3-3.5 mm longis, 0.7 mm latis; 2 mm long, minutely furfuraceous. Sepals pale nonbus adscendentibus brevipediccllatis, pedicellis 1- , t . ^ -^ a ^ t t 2 mm longis minute furfuraceis; petalis albidis lanceo- S'^^"' lanceolate, acute, 3-4.5 mm long, 1 mm latis subacutis vcl obtuse acutis baud unguiculatis 3 ^i^e, dorsally sparsely furfuraceous in lower half. Petals white, lanceolate, subacute or obtusely acute, not unguiculate, 3 mm long, 1 mm wide. Anthers suborbicular-oblong, 0.5 mm long, ba- sally bilobed; filaments white, 1.2 mm long. Caulescent, small, herbaceous plant, flowering Ovary inferior, pale green, subclavate-cylindric, 3.7 dm tall; stem erect, 13 cm tall. Leaves as- 3 mm long, 1 mm wide at summit, 0.7 mm wide cending, pale dull green both sides with about at base, pale brown furfuraceous; ovules caudate- 10 parallel, slightly darker longitudinal lines be- appendaged at both ends. mm longis, 1 mm latis; antheris suborbiculari-oblongis 0.5 mm longis; ovario inferiore subclavato-cylindrico 3 mm longo; ovulis extremitatibus appendicibus cau- datis. coming bronzy where entering sheath, submem- This species of Brocchinia is characterized by branous, flexible, concave above, convex below, its bipinnate inflorescence with lepidote, simple, Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299. Ann. Missouri Bot. Gard. 74: 85-1 16. 1987. 86 ANNALS OF THE MISSOURI BOTANICAL GARDEN [Vol. 74 2.5mm 10cm Figure I. Brocchinia oliva-estevae.—A. Habit. — B. Flower with bract 1987] STEYERMARK-VENEZUELAN GUAYANA 87 racemose axes, primary bracts extending from Va From the related P.foveolata Steyerm. of Ce- to '/2 the length of the rachis, shortly pedicellate rro de la Neblina, the new taxon differs in the flowers, non-unguiculate petals, and narrow sub- palmately five-nerved leaves, which are pubes- membranous, slightly nerved, short leaves only cent along the nerves of the upper and lower 10 cm long by 1.8 cm wide, which are not con- surfaces, and in the shorter, pubescent petioles, tracted toward the base. It is most closely related which are proportionately shorter in relation to to B. cowanii L. B. Smith of Cerro Moriche, Terr. the length of the leaf blade. Compared with P. Fed. Amazonas, Venezuela, in having a bipin- p^/Zo/V/t'aKunth, it differs in the non-peltate, non- nate inflorescence with non-unguiculate petals, sulcatc leaves with pilosulous nerves on the up- but differs from that taxon in the scape bracts per surface, but mainly glabrous below on the shorter than the intemodes and in the shorter leaf surface itself, with leaf margins ciliolate only sepals and petals. in the uppermost Va-^A , and in the petioles short- It is a pleasure to name this interesting species er than the leaf blades, for Mr. Francisco Oliva Esteva, Venezuelan landscape architect, an avid student of Brome- liaceae, and author of several books on orna- Peperomia gentryi Steyerm., sp. nov. type: mental plants of Venezuela. PiPERACEAE Peperomia marahuacensis Steyerm., sp. nov. type: Venezuela. Territorio Federal Ama- zonas: Depto. Atabapo, Cerro Marahuaca, summit, in a zanjon, "Sima'' south and southeast of Summit Camp, 3°37'N, 65^23'W, 2,520-2,620 m, 26-27 Feb. 1985, Venezuela. Territorio Federal Amazonas: Cerro de la Neblina, Camp V, valley north base of Pico Cardona, 0°49'N, 66^0'W, 1,250 m, 21-24 Mar. 1984, Ronald Licsner <&. Brian Stannard 16901 (holotype, MO; iso- type, VEN). Herba repens; foliis alternis late ovatis vel subrhom- bico-ovatis apicc acutis vel subacutis basi truncatis vcl late obtusis 4.5-9 cm longis, 3-5.5 cm latis a 5-1 1 mm Julian A. Steyermark