Usually a small to medium, flat-crowned tree 3-8(12) m. high; young branchlets densely spreading-hairy, the hairs at first golden then grey; the epidermis later falling off to expose powdery rusty-red bark. Stipules spinescent, up to 5 cm. long, never inflated; other prickles absent. Leaves with petiole 2-4 mm. long which, like the rhachis, is densely clothed with at first golden then grey spreading hairs; pinnae of well-developed leaves of mature shoots 15-44 pairs (reduced leaves with fewer pairs sometimes also present), mostly 1-2.5 cm. long; leaflets numerous, (1)1.5-2.8 x 0.4-0.7 mm. Flowers white to cream, in heads; heads c. 2-20 per axil, aggregated into a sort of terminal “raceme”, subtended by young to scarcely developed leaves; involucel below the middle of the almost or quite eglandular 1-2 cm. long peduncle, rarely basal. Corolla ± densely pubescent on the lobes outside, about 11/2 times as long as the calyx. Pods dehiscent, 7.5-14 x 1.2-2.3 cm., straight, glabrous or very slightly pubescent, flattened, not constricted between the seeds, grey-brown to olive, slightly ± longitudinally venose and often somewhat irregularly wrinkled. Seeds brown, 5-9 x 5-6.5 mm., smooth, ellipsoid to suborbicular, somewhat compressed; areole 3.5-5 x 2-2.8 mm.