Moderate or large tree, bark grey or dark brown, hard and tough, branchlets pale, striate, puberulous when young; primary rachis downy pubescent, usually with a large gland near the base of petiole and several, small glands between upper pinnae; spines variable in length, stipular spines paired, long, white, straight; pinnae 6-9 pairs, secondary rachis slightly pubescent; pinnules 10-15 pairs, crowded, elliptic, linear, oblong, glabrous, rigidly coriaceous; flowers pale yellow in heads of large, terminal, densely tomentose panicles, about 30 cm or more, heads numerous, globose; bract ovate, minute; calyx campanulate, teeth-5, short, pubescent; corolla 5-lobed, hairy outside, twice as long as the calyx; stamens many, free, much exserted; ovary stipitate, many ovuled, style filiform; pods sessile, subdehiscent, ligulate, flat, thin, slightly curved, clothed with pale brown or grey, persistent tomentum; seeds 10-15, angular, ovoid, pale brown.