Tree to 27 m high with a rounded, flattened and somewhat spreading or irregu­larly open crown. Bark pale or dark greyish-yellow to brown or almost black, rough, irregularly fissured, flaking, often with persis­tent prickles scattered over the surface; young branchlets pale or dark greyish-yellow or reddish-brown to black, flaking, often minutely, subglabrous to densely pubescent. Stipules not spinescent, in pairs, ± linear, 1-3,5 x 0,2-0,6 mm, densely pubescent, soon deciduous. Prickles in pairs below the nodes, strongly recurved, often broad-based, grey to reddish-brown or black, 3-9 mm long. Leaves: petiole (0,4)1-2,3(3,5) cm long, adaxial gland often present, variable in position, 0,3-0,8 mm in diam.; rhachis (0)3,4-7,2(9,1) cm long, subglabrous to densely pubescent, abaxial surface usually without recurved prickles, eglandular or with a gland at the junction of the top pinna pair or top 1-3 pairs; pinnae (1)3-13 pairs; rhachillae 0,6-5,7 cm long, subglabrous to densely pubescent; leaflets (1)4-19 pairs per pinna, 1,2-20,2 X 0,8-13,1 mm, very variable in shape, linear to linear-oblong or obovate, obovate-oblong to ± orbicular, apex acute to rounded, usually markedly asymmetric basally, veins often prominent below, varying from glabrous above and/or below to sparingly or densely pubescent above and/or below, typically pubescent and with a small basal tuft of hairs on the lower surface. Inflorescences spicate, fascicled, often crow­ded into a terminal raceme, or occasionally solitary. Flowers yellowish-white, sessile or almost so; spikes 1,4-8,5(14,6) cm long; peduncles 0,4-2 cm long, sparingly to densely pubescent, rarely subglabrous. Calyx campanulate, often tinged with pink or distinctly pinkish-red, sparingly to densely pubescent, tube 0,7-1,6 mm long, lobes 0,4-1,1 mm long. Corolla often tinged with pink or pinkish-red, glabrous or apices of lobes sparingly pubescent, tube 1,5-2,1 mm long, lobes up to 1,2 mm long. Stamen-filaments free, up to 6 mm long; anthers ± 0,15 mm across, with a deciduous apical gland. Ovary to 1,6 mm long, glabrous, shortly stipitate. Pods reddish- or purplish-brown, 4,1-16,9 x 0,9-2,4 cm, straight, linear-oblong, ± acuminate to mucronate apically, longitudinally dehiscent, coriaceous, obscurely venose, glabrous or sparsely pube­scent near the margins and stipe. Seeds olive-to reddish-brown, subcircular-lenticular, 6-13 x 6-11 mm, compressed; central areole 4-8 x 3-8 mm, horse-shoe shaped.