Tree, 4-20 m tall, densely tomentose on most parts, sparsely so on upper surface of leaflets; stems with prominent ribs extending below petioles. Petioles terete, to 7.5 cm long; rachis winged, the interfoliar glands unusually large for the genus, 3-5 mm wide; leaflets in 3-6 pairs, oblong to lanceolate-elliptic, acuminate, rounded at base, the terminal pair 8-25 cm long, 3-11 cm wide. Spikes axillary in groups of 1-7; peduncle, floral rachis, and calyx cinereous-tomentose; rachis flattened, angulate; bracts ca 4 mm long and ca 2 mm wide; flowers sessile; calyx 3-5 mm long, irregularly lobed, the sinuses 1-4 mm deep; corolla 7-11 mm long, sericeous, the lobes 1-4 mm long; stamens and style to ca 30 mm long. Legumes +/- terete, many-ribbed, 15-40 (120) cm long, 1.5-2.5 cm diam. Croat 11721, 11966. Mexico to South America; West Indies. In Panama, known from most areas of tropical moist forest and from tropical wet forest in Coclé. Reported from premontane wet forest in Costa Rica (Holdridge et al., 1971).