Tree 2-15 m. high, unarmed; crown conical or rounded; all parts (except flowers) ± densely pubescent or puberulous. Leaves: petiole 1.5-2.5 cm. long, often with a gland above; rhachis usually 4-12 cm. long, with numerous raised glands all along its upper side both at and between insertions of pinnae-pairs; pinnae (8)12-21 pairs; leaflets usually in 16-70 pairs, 1.5 x 0.5-0.75 mm., linear-oblong. Flowers pale-yellow, fragrant, in heads 5-8 mm. in diam. on peduncles 2-6 mm. long, panicled. Pods dehiscing along one margin only, usually c. 3-10 x 0.5-0.8 cm., with 3-12 joints, ± grey-puberulous, jointed, almost moniliform (in Australia forms with less moniliform, almost glabrous pods occur). Seeds black, 5 x 3.5 mm., smooth, elliptic, compressed; caruncle conspicuous; areole 3.5 x 2 mm.