Normally a tree 2.5–12 m high; bark rough, not flaking; branchlets grey-brown to purplish-brown, glabrous to puberulous. Stipular spines all short and hooked or straight and up to 7 mm long, or with long straight spines up to 6 cm long intermixed, or sometimes all spines long and straight. Leaves: pinnae 1–9(–17) pairs; leaflets 4–35 pairs, 0.5–4 x 0.25–1.25 mm, glabrous or puberulous. Flowers white or cream, in heads; peduncles up to 2.5(–3.5) cm long, with the involucel below or above the middle. Calyx up to 1 mm long. Corolla up to c. 3 mm long. Pods straight, linear-oblong, dehiscent, 2–12 x 0.7–1.5(–2.2) cm, brown to purplish, with oblique veins which converge to become longitudinal in the middle of the valves, glabrous or puberulous especially near the base. Seeds subcircular, up to 8 mm in diam.; areole up to 4.5–5 mm.
