Trees 2–15 m tall. Leaves slightly congested at the branch tips, imparipinnate with one pair of leaflets, obtrullate in outline, (1.9–)2.1–3.5(–4.4) × 1.8–2.9 cm; rachises glabrous to sparsely villous with resinous exudate, points of leaflet attachment with a tuft of long hairs; stipular sheaths apically acute, densely villous on the outer surfaces; leaflets elliptic to obovate in outline, second pair from the terminal leaflet the largest, one of this pair (1.4–)1.8–2.7 × 0.4–0.7 cm; margin crenate with 5–9 teeth, apically obtuse to emarginate, basally attenuate; upper leaflet surfaces glabrous; lower leaflet surfaces covered with very short, white pannose hairs and resinous exudate. Inflorescences pendant, (2.1–)2.7–7.1 cm long, bearing 5–11 flowers; floral bracts 3.8–4.9 mm long, narrowly triangular, densely villous on the outer surface; rachises villous. Flowers 5.4–8.8 mm diam.; sepals 4, ovate, green, densely villous outside; stamens 17–25, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.1–3.0 mm long. Fruits turbinate, with 2–5 irregular flattened ridges with a series of spines, densely villous; 3.9–7.2 × 3.8–6.5 mm including spines. Diploid, hexaploid in cultivated plants.