Tree, to 30 (40) m tall, to 1 m dbh; young branchlets with brownish short pubescence, becoming glabrous and sometimes lenticellate in age. Leaves bipinnate with 3-5 pairs of pinnae, the axes minutely pubescent; petioles 4-7 cm long; stipules acicular, caducous; rachis 8-16 cm long, bearing a large cupular gland to 1 cm long between pairs of basal pinnae and a smaller gland at node of successive pair; pinnular rachis to 15 cm long, with small glands at nodes; leaflets in 7-12 pairs per pinna, asymmetrical, ovate to oblong, obtuse to rounded at apex, usually obtuse at base, 2-5 cm long, l-2 cm wide, minutely appressed-puberulent with longer trichomes on midrib. Flowers in condensed umbels or short spikes; peduncles 5-12 cm long, ferruginous-tomentose; floral rachis ca 5 mm long; pedicels 1-2.5 mm long; flowers pale green, 9-12 mm long excluding stamens, with minute, brown, appressed trichomes outside; calyx 5-6 mm long, the lobes irregular, ca 2 mm long, sometimes +/- cleft on one side; corolla usually 5 (6)-lobed ca one-third its length, fused to the staminal tube near base; stamens many, ca 3 cm long, the staminal tube nearly as long as corolla. Legumes linear, short- stipitate, curved into a nearly complete circle ca 6 cm diam, to 12 cm long and 2-2.5 cm wide, very thick at seminiferous areas, the valves splitting apart and twisting to display seeds; seeds flattened, ovoid, ca 8 mm long, on alternate segments of the valve. Croat 5205.