Shrub up to 4 m high; young branchlets usually purplish-brown, conspicuously lenticellate, glabrous or almost so. Stipular spines straight or slightly curved, 1–2.2 cm long. Leaves with 2(–3) pairs of pinnae, the lower pair much shorter than the upper; leaflets 1–2 pairs on lower pinnae, 3–5(–7) pairs on upper, 6–15 x 3.5–9 mm, obliquely obovate or elliptic, veined, glabrous. Flowers white, in heads; peduncles 2–4 cm long, finely pubescent; involucel at or somewhat below the middle of peduncle. Calyx 3–3.5 mm long, pubescent. Corolla 4.5–5.5 mm long, pubescent. Pods straight or slightly curved, ± cylindrical and constricted between the seeds, dehiscent, (7–)9.5–16 x 1–1.5 cm, dark brown, longitudinally veined, puberulous. Seeds blackish, ellipsoid to subglobose, 10–12 x 6.5–7.5 mm, punctate; areole 8–10 x 4–5 mm.
