Rondeletieae (Rubiaceae): Part I (Rustia, Tresanthera ... - CNCFlora

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32 Flora Neotropica Peculiar anther extensions were observed in Rustia and Molopanthera. In R. simpsonii the base of the anthers have papillose spheroid extensions. In M. paniculata the flower buds are bent upward, and when the flowers open the two lower filaments often remain bent upward, with two pairs of adjacent anthers connected to each other by their pointed extensions at both ends (forming two cup-shaped units), with the fifth filament remaining free (see Fig. 85C). The peculiar floral morphology of Molopanthera seems to be a mechanism of pollen projection, which has been reported by Schumann (1891: 10) but not personally observed. Apparently the pollen is shed, when the flower is still closed, into a spherical mass, and the single filament projects this mass onto the pollinators (most probably bees). [A detailed descrip- tion of such pollen projection mechanism in Poso- queria has been explained by Halle (1967: fig. 40)]. Styles Styles in these genera are terete, glabrous, exserted beyond the corollas, and terminated by two style branches (stigmas). Most species of Chimarrhis are exceptional in having styles minutely costate (C. parviflora, C. latifolia, C. cubensis, C. jamaicensis, C. cymosa, C. microcarpa, C. speciosa, C. turbinata, and C. duckeana) or strigose to puberulent (C. turbinata, C. barbata, C. duckeana, and C. gentryana). When the flowers are presented in a horizontal or oblique position, the styles are curved upward in Rustia, Condaminea, Chimarrhis, and Pogonopus (and Pinckneya). The stigma branches are generally ovate-oblong, with stigmatic surfaces minutely (40x) papillose. In Chimarrhis, the stigmas are exserted (and receptive) beyond the still-closed corollas (protogynous). Dioicodendron is exceptional in being dioecious; in its female flowers the styles are exserted beyond the corollas, and the stigmas are arcuate with their tips still connected at maturity. None of the genera studied are heterostylous [Chimarrhis was erroneously reported as such by Urban (1899)]. Ovaries In the genera studied the ovaries are inferior and bilocular, with axile placenta on which numerous ovules are horizontally (vertically in Chimarrhis and Molopanthera) inserted. The ovaries are topped with a nectariferous disk, composed mainly of parenchyma cells. In some genera (Rustia, Tresanthera, Chimar- rhis) the shape, persistence, and vestiture of the caly- ces in mature capsules proved to be useful taxonomic characters at the specific and varietal levels. Shape and vestiture of the disks in the generic and specific descriptions below are referred to as they appear in mature capsules. Fruits In the genera here studied, fruits are multiseeded, bilocular, woody capsules with a central placenta. In early stages the exocarp and mesocarp of immature fruits are green and fleshy, becoming brown and woody at maturity. Mesocarp fleshiness has been considered by many botanists (Hooker, 1873; Baillon, 1880; Schumann, 1889, 1891; Verdcourt, 1958; Bremekamp, 1966; Steyermark, 1974; Robbrecht, 1988, 1993) to be a key character in establishing tribal and generic delimitations. It has been recently demonstrated (Bremer, 1992; Bremer & Eriksson, 1992; Bremer & Struwe, 1992) that fleshiness of the mesocarp in mature fruits has evolved independently several times within the Rubiaceae. Nevertheless, its total dismissal as a taxonomic character would deprive systematists of a useful source of data (Delprete, 1996d). Size and shape of capsules are rather consistent within the same genus, offering a good practical aid for immediate generic identification. The shapes and dimensions of capsules are quite variable among genera: Rustia globular, obovoid to turbinate, 4-23 x 4- 9 mm; Tresanthera ellipsoid to obovoid, 15-24 x 8- 12 mm; Condaminea obovoid-oblong, 14-40 x 6-11 mm; Picardaea oblong, 15-19 x 6.5-8 mm; Dolichodel- phys narrowly cylindrical, 14-23 x 3.5-5 mm; Pogonopus obovoid to ellipsoid, 5-10 x 4-9 mm (and Pinckneya bilobed-subglobose, 10-25 x 15-25 mm); Chimarrhis obovoid to turbinate, 1.5-12 x 1.5-6 mm; Dioicodendron obovoid to turbinate, 3-4.5 x 2-3.5 mm; Molopanthera bilobed-subglobose, 2-3 x 4-5 mm; and Parachimarrhis, biglobular, 3-4.5 x 1.5-2.5 mm. The mode of capsular dehiscence is a valuable character in establishing generic boundaries among the genera studied. Mature capsules of Chimarrhis, Dioicodendron, and Dolichodelphys have septicidal dehiscence, whereas Rustia, Tresanthera, Picardaea, Condaminea, and Pogonopus (and Pinckneya) have loculicidal dehiscence. Picardaea has a unique dehiscence pattern, splitting loculicidally but with the two halves remaining attached at the apex and base (no apical dehiscence), as in Macrocnemum (under which it was originally described). I recently introduced the term "secondary dehiscence" (Delprete, 1995a, 1996d), referring to the splitting that occurs in advanced stages of capsule maturity, usually after and perpendicular to primary dehiscence. Secondary dehiscence may or may not occur, depending on the genus, usually occurring only at the apices of old capsules; it is a character of some
Introduction to the Neotropical Genera Studied 33 taxonomic importance at the generic level. Second- examined and mounted on SEM stubs using a light ary dehiscence has been observed in old capsules of microscope. The mounted samples were gold-coated some species of Rustia, Tresanthera, Pogonopus, with a Ladd sputter-coater, and then studied, mea- Chimarrhis, and Dioicodendron. Secondary dehis- sured, and photographed using a Phillips 515 scancence has not been found (and is probably absent) in ning electron microscope (SEM) housed at the Cell Condaminea, Picardaea, and Dolichodelphys. Research Center of the University of Texas at Austin. The dimensions of the seeds are given first by the SEED MORPHOLOGY ranges of length and second by the ranges in width. Voucher specimens are cited in the explanations of Seed morphology has been considered for a long the microphotographs. time to be of cardinal importance in Rubiaceae systematics (Hooker, 1873; Baillon, 1880; Schumann, Rustia (Figs. 5A-F, 6A-H). Seeds of irregular size 1888a, 1888b, 1889, 1891; Verdcourt, 1958; and shape, flattened, 0.67-2.9 x 0.25-1.33 mm; acute Bremekamp, 1966; Steyermark, 1974; Robbrecht, at base; acute, truncate, or uncinate at distal end; testa 1988, 1993). Recent investigations (Bremer, 1992; shallowly reticulate, cells elongated and longitudinally Bremer & Eriksson, 1992; Delprete, 1995a, 1996d) oriented, interspaces smooth to sparsely granular. have shown that the importance given to seed mor- Species of which seeds were available were observed phology (i.e., endosperm fleshiness, presence of to have the following dimensional ranges: R. costawings, etc.) in the classification of this family needs ricensis (Fig. 5A,B) 0.75-1 x 0.25-0.4 mm; R. occireevaluation. Exotesta sculpturing is an important dentalis (Fig. 5E) 1.06-1.26 x 0.67-0.83 mm; R. alba taxonomic trait at the generic and specific levels. The (Fig. 6F) 2.25-2.9 x 0.65-0.75 mm; R. rubra (Fig. presence of wings (testal outgrowths) in seeds was 5F) 1.16-1.5 x 0.33-0.53 mm; R. viridiflora (Fig. 6E) considered a very important taxonomic character by 0.87-1.27 x 0.33-0.83 mm; R. schunkeana (Fig. 6A) Baillon (1879), Schumann (1888a, 1888b, 1889, 1.17-1.67 x 1-1.33 mm; R. thibaudioides (Fig. 6C,D) 1891), and Andersson and Persson (1991), but 1.4-1.5 x 0.75-1.25 mm; R. venezuelensis (Fig. 6G,H) Bremekamp (1966) and Verdcourt (1958) considered 0.93-1 x 1 mm; R.formosa (Fig. 5C) 1.4-1.6 x 0.48it to be of little importance. Bremer and Eriksson 0.5 mm; R. angustifolia (Fig. 6B) 1.33-1.5 x 0.4-0.73 (1992) concluded that winged seeds are "not predomi- mm; R. gracilis (Fig. 5D) 0.87-1.16 x 0.43-0.67 mm. nant in any of the six groups" of their cladistic analysis, which "may indicate that winged seeds are more Tresanthera (Fig. 7A-C). Seeds generally ob- 'evolutionary plastic' than the fleshy fruits." As a triangular, flattened, 1-1.5 x 0.33-0.53 mm; acute at result of a phylogenetic analyses using morphologi- base, truncate at distal end; testa reticulate, cells eloncal characters, Delprete (1995a, 1996d) concluded that gated and longitudinally oriented, interspaces smooth to the presence and general shape of seed wings is de- sparsely granular at margins. The seeds of this monopendent on the insertion of the seeds (whether later- typic genus have been measured as follows: T. ally or ventrally attached) on the placenta and their condamineoides var. condamineoides (Fig. 7C) 1.33-1.5 final position at maturity (horizontal or imbricate). x 0.37-0.53 mm; T. condamineoides var. thyrsiflora (Fig. Seed wings of different genera should not be assumed 7A,B) 1-1.2 x 0.33-0.5 mm. to be homologous, because of their different origins and developments. When properly used, seed mor- Condaminea (Fig. 7D-H). Seeds generally obphology provides a good set of taxonomic characters long, irregularly 3-4-angular, 0.57-0.77 x 0.13-0.33 for inferring the phylogeny of the Rubiaceae. mm; acute at base, truncate at distal end; testa shal- In most genera, the seeds are laterally attached and lowly reticulate, cells elongated and longitudinally horizontally positioned within the capsules (Fig. 5A), oriented, interspaces smooth. The seeds of C. corymexcept for Chimarrhis and Molopanthera, where the bosa (Fig. 7D-F) are 0.57-0.77 x 0.13-0.33 mm. The seeds are peltate on the placenta and umbilically at- dubiously placed C. elegans have seeds trapezoid (Fig. tached. In Chimarrhis the placenta is central and ver- 7H), 1.3-1.87 x 0.9-1.33 mm, testa densely reticutical, while in Molopanthera the placenta is globular late, cells variously oriented, and granular interspace. and supported by a short stalk in a central position. In All the previous characters place this species within most genera, seeds are minute and of irregular shape Rustia, but its floral morphology is similar to that of (but in Parachimarrhis are hemi-elliptic in outline, with Condaminea, where it is tentatively maintained. lateral linear hilum) and are adapted to wind dispersal. Seeds for SEM studies were removed from mature Picardaea (Fig. 8F). Seeds generally oblong to capsules of herbarium specimens. The seeds were first trapezoid, irregularly 3-4-angular, 0.5-0.7 x 0.2-0.4
Page 1 and 2: Organization for Flora Neotropica R
Page 3 and 4: Flora Neotropica Published for Orga
Page 5 and 6: Rondeletieae (Rubiaceae)-Part I (Ru
Page 7 and 8: Introduction to the Rondeletieae 3
Page 19 and 20: Molopanthera 1 Br Seasonal and Atla
Page 27 and 28: Introduction to the Neotropical Gen
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Systematic Treatment of the Genera
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Literature Cited 203 ACKNOWLEDGMENT
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Literature Cited205 . 1997a. Revisi
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Literature Cited 207 Orsted, A. S.
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Numerical List of Taxa209 Waha, M.
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List of Exsiccatae211 Chavez-Alfaro
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List of Exsiccatae213 Howell, J. T.
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List of Exsiccatae 215 Plowman, T.
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Nomenclatural List 217 Zanoni, T. &
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Nomenclatural List 219 N. shaferi S
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Index of Scientific Names 221 INDEX
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Index of Scientific Names 223 [Hame
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Index of Scientific Names 225 parae
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Rondeletieae (Rubiaceae): Part I (Rustia, Tresanthera ... - CNCFlora

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