Platysepalum

Taxonomy

Platysepalum F.M.J. Welwitsch ex J.G. Baker In D. Oliver, Fl. Trop. Africa 2: 131. 1871.

Subfamily: Faboideae.
Phylogenetic Number: 3.7.
Tribe: Millettieae.
Species Studied - Species in Genus: 3 studied; ca. 12 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 10–17 cm long; 2–4 cm wide; 0.5–1 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical, or asymmetrical; falcate, or fusiform; with both sutures parallelly curved; not inflated; compressed; without beak, or with beak; straight; with solid beak the same color and texture as fruit; rounded at apex, or tapered at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; long tapered at base to tapered at base to rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous to ligneous; seed chambers externally invisible, or visible; seed chambers with the raised seed chambers not torulose; margin not constricted, or constricted; margin slightly constricted along both margins; margin without sulcus; margin embellished, or plain; margin with ridge(s); nonstipitate; with all layers dehiscing (tardily); splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves twisting. Replum invisible. Epicarp dull; monochrome; brown; with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence, or 2 types of pubescence; densely velutinous; with pubescence brown to golden; with long and short golden to brown hairs intermixed; with pubescence uniformly distributed; with simple hairs; stiff; with hair bases plain; eglandular; without spines; smooth, or not smooth; with elevated features; veined; transversely veined relative to fruit length; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thick; surface not veined; 2-layered, or 3-layered; without balsamic vesicles; without fibers; without reniform canals; with solid layer over solid layer, or spongy layer over solid layer; with solid layer over 2 distinct solid layers; ligneous. Endocarp present; visible; dull; opaque; monochrome, or mottled; brown, or white; with mottling more or less uniform (dark); with brown overlay; floury-filamentous; without adhering pieces of testa; subseptate, or nonseptate; with septa eglandular; chartaceous; exfoliating in part, or not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 3–5; length parallel with fruit length, or oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus 1–4 mm long; of 1 length only; flattened, or thick; curved, or straight. Aril present; fleshy, or dry; when fleshy annular; crenate; covering less than 1/2 of seed; when dry rim-aril and tongue-aril; entire; tan.

Seed: 11–27 mm long; 10–13 mm wide; 3–5 mm thick; not overgrown; not angular; symmetrical, or asymmetrical; nearly circular, or ovate (irregularly); compressed to flattened; with surface smooth; without visible radicle and cotyledon lobes; with shallow hilar sinus; without umbo on seed faces; without medial ridge on each face. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; dull; not modified by a bloom; colored; monochrome; black to brown (dark); glabrous; not smooth; with elevated features, or recessed features; finely, transversely ridged; pitted with small separate pits; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed, or fully concealed; concealed by aril, or funicular remnant; with faboid split; with the lips of the faboid split lighter colored than the rest of the hilum and therefore conspicuous; larger than punctiform; 1.5–5 mm long; with curved outline; elliptic to fusiform; apical at apex of radicle tip, or apical according to radicle tip but marginal according to seed length; recessed; within rim, or not within corona, halo, or rim; rim color of testa. Lens barely discernible; 1–4 mm long; with margins straight; linear, or oblong; not in groove of raphe; confluent with hilum; mounded, or flush; same color as testa; black to brown; not within corona, halo, or rim. Endosperm absent. Cotyledons smooth, or not smooth; wrinkled; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; with margin(s) recessed; with 1 margin recessed; recessed on same side as radicle; tan; inner face flat; glabrous on inner face. Embryonic axis oblique to right angled; oblique to length of seed to perpendicular to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip curved; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Tropical Africa.

Old World; Africa.

Generic Notes

Gillett (1960a) provided a key to the species.

Tribal Notes

Tribe Millettieae

Geesink (1981) treated this tribe, as others before him, under the tribal name Tephroseae, but we now know that its correct name is Millettieae. Recent tribal studies (Geesink, 1981, 1984; Polhill, 1994a, 1994b) have arranged the genera in alphabetical order without phylogenetic numbers. Geesink (1984) monographed tribe Millettieae, and presented descriptive notes about fruits and seeds and in situ fruit and seed drawings. However, we are not entirely following Geesink (1984) for generic parameters because he either questioned the status of many of his new genera or did not make the necessary species transfers. The few new genera which he clearly recognized are being accepted. Lavin et al. (1998) developed a preliminary infratribal classification of six informal groups using phytochrome nucleotides: Millettia group, Lonchocarpus group, Derris group, Tephrosia group, "primitive" group, and Phaseoleae group. Lavin (1987) transferred Sphinctospermum to Millettieae. Lavin and Doyle (1991) carried out cladistic analyses integrating morphological and chloroplast DNA data, and concluded that it is a member of Robineae where we have placed it (now 8.12).