Subfamily: Faboideae.
Phylogenetic Number: 3.10.77.
Tribe: Phaseoleae.
Subtribe: Cajaninae.
Species Studied - Species in Genus: 9 studied; 30 in genus.
Fruit: A legume; unilocular; 1.5 cm long; 0.9 cm wide; 0.7 cm thick; length less than twice as long as width; with deciduous androecial sheath; with deciduous corolla; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; asymmetrical; irregular, or harp-shaped; with both sutures unequally curved; not inflated; terete, or compressed; with beak; straight; with solid beak the same color and texture as fruit; short tapered at apex, or rounded at apex; aligned with longitudinal axis of fruit; rounded at base, or short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin plain; 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; puberulent; with pubescence golden; with pubescence uniformly distributed; with simple hairs; stiff; with hair bases swollen, or plain; glandular; with glandular dots; without spines; smooth, or not smooth; with elevated features; veined, or not veined; transversely veined relative to fruit length; not tuberculate; glandular dotted; exfoliating in part, or not exfoliating; with cracks, or without cracks; cracking oblique to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; chartaceous. Endocarp present; visible; dull; opaque; streaked; tan; with brown overlay, or gray overlay; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1, or 2; length oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.1–1.1 mm long; of 1 length only; flattened; triangular. Aril present; dry; when dry rim-aril, or 2-lipped rim-aril (rarely); entire; covering less than 1/2 of seed; with tongues (or flap) on lips of 2-lipped rim-aril; with 1 tongue or flap on 1 lip of 2-lipped rim-aril, or 2 tongues or flaps, 1 on each lip of 2-lipped rim-aril (rarely); cream.
Seed: 3–5.6 mm long; 2.5–4.2 mm wide; 2.5–4.3 mm thick; not overgrown; not angular, or angular; symmetrical, or asymmetrical; circular, or irregular, or reniform, or rhombic; terete to compressed; with surface smooth; without visible radicle and cotyledon lobes (mostly), or with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; with shallow 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, or dull; not modified by a bloom, or modified by a bloom; colored; monochrome, or mottled; with frequent mottles; black, or brown (dark); with black overlay, or brown overlay; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present, or absent; transverse. 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; 1–1.5 mm long; with curved outline; elliptic; apical according to radicle tip but marginal according to seed length, or apical at apex of radicle tip (rarely); flush; within rim, or within rim and within halo; halo darker than testa; rim color darker than testa, or of testa, or lighter than testa (rim lighter if with halo). Lens discernible; 0.5 mm long; with margins curved; circular; not in groove of raphe; confluent with hilum; mounded; dissimilar color from testa; darker than testa; brown; within rim; rim color of testa, or darker than testa. 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; notched at radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; yellow, or tan; inner face flat; glabrous on inner face. Embryonic axis deflexed, or oblique; oblique to length of seed, or perpendicular to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose, or triangular; lobe tip straight; deflexed and parallel to cotyledon width, or oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule well developed to rudimentary (rarely); glabrous.