Cymbosema

Taxonomy

Cymbosema G. Bentham J. Bot. (Hooker) 2: 61. Mar 1840.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.19.
Tribe: Phaseoleae.
Subtribe: Diocleinae.
Species Studied - Species in Genus: 1 studied; 1 in genus.

Description

Fruit: A legume; unilocular; 4.4–6 cm long; 1.8–2.2 cm wide; 0.4–0.7 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; slightly curved; not plicate; not twisted; asymmetrical, or symmetrical; oblong, or falcate; with both sutures parallelly curved; not inflated; compressed; with beak; declined; with solid beak the same color and texture as fruit; short tapered at apex; oblique with longitudinal axis of fruit; rounded at base, or short tapered at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally invisible; margin constricted, or not constricted; margin slightly constricted only on 1 margin; margin without sulcus; margin embellished; margin with ridge(s); wing(s) absent; nonstipitate; with all layers dehiscing; 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; sericeous; with pubescence golden; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; smooth; not veined; not tuberculate; not exfoliating; with cracks; cracking oblique to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 2-layered; without balsamic vesicles; with fibers; without reniform canals; with fibers over solid layer (resembling tomentose layer where endocarp exfoliates); coriaceous. Endocarp present; visible; dull; opaque; monochrome; brown; smooth; without adhering pieces of testa; septate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; exfoliating in part; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 2–5; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus 10–15 mm long; of 1 length only; flattened; triangular. Aril present; dry; when dry rim-aril; crenate; covering less than 1/2 of seed; without tongue (or flap) on lips of 2-lipped rim-aril; tan.

Seed: 10–14 mm long; 6–8.5 mm wide; 4–5.6 mm thick; not overgrown; not angular; symmetrical; oblong to ovate, or reniform; compressed; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy; not modified by a bloom; colored; monochrome; dark brown; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present; concentric. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; 13–13.2 mm long; with straight outline; linear; marginal according to radicle tip; raised; within rim; rim color darker than testa. Lens discernible; 0.5–0.8 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; flush; same color as testa; dark brown; not within corona, halo, or rim. Endosperm present; trace; not pluglike and not resembling tip of radicle; restricted to region of embryo; adnate to testa. Cotyledons smooth; 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; partially concealing radicle; split over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; tan; inner face flat; glabrous on inner face. Embryonic axis oblique; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; triangular; lobe tip straight; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule moderately developed; glabrous.

Distribution

Tropical Mexico, Central America, and South America reaching to Brazil (Amazonia).

New World; Mexico, Central America, and South America; Peru, Brazil, Ecuador, and the Guianas.
 

Generic Notes

Maxwell (1970) monographed Cymbosema.

Tribal Notes

Tribe Phaseoleae

Bruneau et al. (1995) carried out cladistic analyses of tribe Phaseoleae using chloroplast DNA restriction site data. Their results indicated that the tribe is not monophyletic and that the tribal delimitations between Phaseoleae and Desmodieae (11) and between Phaseoleae and Millettieae (7) are problematic.