Vines, woody, in clumps, or high-climbing lianas. Leaves trifoliolate, the lat-eral leaflets usually smaller than the terminal, the margins entire, revolute, with variable pubescence; stipels setaceous to filiform; stipules lanceolate or triangu-late, produced below insertion or non-produced. Inflorescences erect, usually single and axillary, fasciculate racemose, tuberculate; bracts linear to triangulate, persistent to caducous; bracteoles ovate, flabellate to orbicular, persistent or caducous. Flowers shades of violet, purple and blue; calyx tube 4-5 lobed, pu-bescent within, glabrous or variously pubescent without, the upper lobes partially or completely fused; lamina of the standard oblanceolate to somewhat orbicular, emarginate, basally biauriculate and usually bicallose, glabrous or puberulent, carnose or membranous, the wings free, the lamina obliquely oblong to obliquely ovate, auriculate, occasionally with a spur, the keel petals fused distally, the lamina triangulate to somewhat obliquely oblong, auriculate; stamens 10, the vexillary filament free ca. 3 mm, basally, then fused to the staminal sheath, all the filaments free distally, the anthers dimorphic or monomorphic; pistil com-pressed, geniculate, the ovary villous, the upper style glabrous, the stigma cap-itate, glabrous. Fruits oblong, flat, compressed or turgid, with variable dehis-cence, pubescence variable; seeds large, few, soft-cuboidal or hard-turgid; if small, then many, hard and flat, oblong to sub-orbicular; the hilum linear or short-oblong, encircling ca. '/5 to nearly 1/2 or to ca. 3/4 the testa.
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Cal-tube nearly regular, the lobes 4 by fusion of the upper 2, the lowest lobe exceeding the lateral ones; standard broadly obovate, auricled at base; wings obovate-oblong; keel-pet semi-elliptic, nearly straight; stamens 10, the uppermost one coherent with the others for half its length; fr oblong, flattened, few-seeded, dehiscent, narrowly 2-winged along the upper suture; twining woody or half-woody vines with large, pinnately trifoliolate lvs, minute stipules, and small blue or purple fls borne several at each node on an elongate axis and each closely subtended by a pair of bracteoles. 30, mainly trop. Amer.