An exceedingly variable species. Tree, c. 1.2-18 m high, variable in shape; bark on trunk rough, fissured, blackish, grey or brown; young branches almost glabrous to subtomentose. Stipules spinescent, up to 8 cm long. Leaf often with 1-2 petiolar glands and others between all or only the topmost of the 2-11 pairs of pin¬nae; leaflets 7-25 pairs, c. 1.5-7 mm long, c.0.5-1.5 mm wide, glabrous to pubescent. Inflorescence axillary pedunculate heads, 6-15 mm in diameter. Flowers bright yellow, involucel from near base to half way up the peduncle. Calyx 1-2 mm long, pubescent or subglabrous. Corolla 2.5-3.5 mm long, glabrous to more or less pubescent outside. Fruit very variable, indehiscent, straight or curved, glabrous to velvety, 4-22 cm long, c.1.3-2.2 cm wide. Seed blackish brown, smooth, 7-9 mm long, 6-7 mm wide, subcircular, compressed, areole 6-7 mm long, 4.5-5 mm wide.