Flat-topped tree, to 16 m. Bark reddish-brown on older trees; pale yellowish-brown, peeling off in papery wads, on younger trees. Young twigs softly hairy. Thorns in straight pairs at nodes. Leaves: pinnae pairs 20-40; leaflets very small, up to 4 × 0.75 mm. Inflorescence of white spherical heads. Involucel in lower half of peduncle. Pods dehiscent.