Small tree 2.5–4.5(–6) m. high; stems brown or sometimes black. Young branchlets grey-puberulous with hairs about 0.1 mm. long or less; older branchlets brown or blackish but without any powdery inner bark. Stipules spinescent, 1.5–5.5 cm. long, a few shorter, straight, pale grey or whitish, some fused at base into ± rounded blackish ant-galls 1.5–3 cm. in diameter. Leaves: petiole 5–10 mm. long, glandular at apex; rhachis (1.5–)3–6.5 cm. long, puberulous like the petiole, glandular between the top 1–3 pairs of pinnae; pinnae 3–10 pairs, mostly 1.5–3.5 cm. long; leaflets 10–22 pairs, glabrous, subacute at apex, 2.5–6 mm. long, 0.8–1.5 mm. wide. Flowers white, in heads; involucel at base of the densely puberulous peduncle. Calyx 1–1.5 mm. long, densely tomentellous outside. Corolla 3–3.75 mm. long, clothed like the calyx outside (except at base). Pods (Fig. 16/52, p. 67) curved or falcate, thinly coriaceous, densely grey-puberulous, mostly attenuate or acuminate at ends, 4.5–7 cm. long, 0.6–1.1 cm. wide. Seeds grey, smooth, ± elliptic or quadrate, compressed, sometimes curved, 9–11 mm. long, 5.5 mm. wide; areole 5–7 mm. long, 2.5–3 mm. wide.
