Subfamily: Faboideae.
Phylogenetic Number: 3.10.37.
Tribe: Phaseoleae.
Subtribe: Glycininae.
Species Studied - Species in Genus: 1 studied; 1 in genus.
Fruit: A legume; unilocular; 6.3–8 cm long; 0.7 cm wide; 0.3–4 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; slightly asymmetrical; nearly linear; with both sutures nearly straight; not inflated; flattened; without beak; tapered at apex; oblique with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; leathery; seed chambers externally barely visible; margin constricted; margin slightly constricted along both margins; 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; drying dark brown to black; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; slightly rugose; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; dark brown to black; smooth; without adhering pieces of testa; subseptate; 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) 7–8; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.5–1.5 mm long; of 1 length only; flattened; triangular. Aril present; dry; when dry rim-aril and tongue-aril; entire; covering less than 1/2 of seed; cream.
Seed: 6.2 mm long; 5 mm wide; 2.5 mm thick; not overgrown; not angular; asymmetrical; elliptic; 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; dull; not modified by a bloom; colored; mottled; with infrequent mottles; dark brown; with brown overlay (lighter); glabrous; smooth; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed; concealed by aril; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; 1.5 mm long; with curved outline; elliptic; apical according to radicle tip but marginal according to seed length; recessed; within rim; rim color of testa. Lens discernible; 1 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; flush; same color as testa; not within corona, halo, or rim. Endosperm absent. Cotyledons not smooth; sulcate; 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; yellow; inner face flat; glabrous on inner face. Embryonic axis oblique; perpendicular to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip curved; deflexed and parallel to cotyledon width; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.