Tree, to 22 m tall and 34 cm dbh; outer bark smooth, light brown; inner bark pale reddish-brown or tan; branchlets 4-angled, +/- lenticellate, glabrate in age. Leaves glabrate in age above except on veins, sparsely short-pilose below, more densely on veins; petiole and rachis narrowly winged to only margined; leaflets in 2 pairs (rarely 3), sessile, broadly elliptic to obovate, rounded to acute or mucronate at apex, obtuse to subcordate and inequilateral at base, the terminal pair 17-28 cm long, 9-17 cm wide, the basal pair much reduced. Flowers in capituliform spikes, the spikes axillary or terminal, in groups of 1-6, with dense bracts; peduncles tomentose, 3-8 cm long; rachis 1-3 cm long; bracts large, to 14 mm long and 11 mm wide, obscuring calyx, tomentose, ovate, deciduous as flowers open; calyx tomentose, 7-9 mm long, the lobes 2.5 mm long; corolla short-sericeous, 15-22 cm long, the lobes to 3 mm long; stamens and style to ca 25 mm long. Legumes flat, 30-70 cm long, 5-8 cm wide, 1.5-3 cm thick, glabrous, the margins not elevated. Croat 10480, Shattuck 925.