Subfamily: Faboideae.
Phylogenetic Number: 3.29.05.
Tribe: Thermopsideae.
Species Studied - Species in Genus: 7 studied; 17 in genus.
Fruit: A legume; unilocular; 1–7 cm long; 0.2–2.5 cm wide; 0.7–2 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx, or deciduous calyx; with calyx shorter than fruit, or equal in length to fruit; without orifice formed by curving of fruit or fruit segments; straight, or curved (slightly); not plicate; not twisted; symmetrical, or asymmetrical; oblong, or ovate, or circular, or elliptic; with both sutures parallelly curved, or 1 straight and 1 curved suture; widest near middle or D-shaped; usually inflated, or not inflated; terete; without beak, or with beak; straight; with solid beak the same color and texture as fruit; rounded at apex, or long tapered at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; long tapered at base, or rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; ligneous, or coriaceous, or membranous (B. megacarpa A.W. Chapman ex J. Torrey & A. Gray); seed chambers externally invisible; margin not constricted; margin without sulcus, or with sulcus; margin plain; wing(s) absent; stipitate, or substipitate; with the stipe 4–13 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; passive. Replum invisible. Epicarp dull, or semiglossy; monochrome; dark to yellowish to reddish to purplish brown, or black (brownish); with surface texture uniform; glabrous, or pubescent and indurate; with hairs appressed (sub), or erect; with 1 type of pubescence; villous; with pubescence gray; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; smooth, or not smooth; with elevated features; veined; reticulately veined; not tuberculate; wrinkled, or rugose; not exfoliating; without cracks; 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; (sub-) ligneous, or coriaceous, or chartaceous. Endocarp present; visible; dull; opaque; monochrome; dark to light brown; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 20–30 (estimated); length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus 3.5 mm long; of 1 length only; thick; straight. Aril absent, or present (really funicular remnant); dry; when dry rim-aril; entire; brown.
Seed: 2.5–4.5 mm long; 2–3 mm wide; 1.6–2 mm thick; not overgrown; not angular; asymmetrical; D-shaped (with inconspicuous radicle lobe); compressed; with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; 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, or glossy; modified by a bloom; colored; monochrome; yellowish to dark brown, or tan, or white; glabrous; smooth, or not smooth; with elevated features; tuberculate (glandular exudates), or blistered cuticle (B. megacarpa A.W. Chapman ex J. Torrey & A. Gray); coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible; from lens to base of seed and terminating (near base); not bifurcating; darker than testa; black; slightly recessed, or flush. Hilum present; partially concealed; concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform, or larger than punctiform; 0.3–0.4 mm long; with curved outline; circular; between cotyledon and radicle lobe; recessed; within rim, or within halo (occasionally and faintly); halo darker than testa; rim color of testa. Lens discernible, or not discernible; with margins curved; circular; not in groove of raphe; adjacent to hilum; 2 mm from hilum; flush; dissimilar color from testa; darker than testa; reddish brown; not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire 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; not concealing radicle; entire over 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; oblique 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.