Small or bushy tree to several meters; branchlets essentially glabrous, with a few longitudinal lines or thin ridges and many prominent lenticels. Leaves mod-erately small, bipinnate, each pinna bifoliolate; petioles mostly 1-3 cm. long, slen-der, subglabrous, somewhat flattened, canaliculate above, bearing a short-columnar, concave gland apically above; axis of the pinna mostly 1 cm. or less long, similar to the petiole except the apical gland sometimes obsolete; leaflets asymmetrically ovate, oblong or obovate, up to almost 6 cm. long and 3.5 cm. wide, obtuse to rounded or subtruncate apically, obliquely obtuse basally, glabrous above and below except barbate basally on the narrow side below; stipules modified as small or moderate thorns or spines to either side of the petiole, a few mm. to 1 cm. long or longer. Inflorescence an axillary panicle, usually subterminal, consisting of a number of pedunculate spikes; peduncles slender, usually 1-2 cm. long at maturity, lightly pubescent or subglabrous; floriferous portion of spike 5-20 mm. long, condensed apically and somewhat more lax baseward; bractlets ovate-lanceolate, scarcely 1 mm. long, persistent, pilosulous. Flowers small, sessile, whitish; calyx cupular, little over 1 mm. long, shallowly lobed, puberulent, 5-angled; corolla funnelform, 3-4 mm.-long, valvate, puberulent at least apically; stamens about 8-9 mm. long, united below into a short staminal tube; ovary stipitate, glabrous, the stipe almost 1 mm. long. Legume linear-circinate, up to 10 cm. long and about 1 cm. wide, frequently coiled upon itself, dehiscent, compressed but turgid at and indented between the seeds, nearly glabrous, reddish; seeds ovoid, lustrous-black.
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