Climbing or trailing herb or liane 3–4.5 m long. Stems densely to sparsely covered with appressed or spreading ferruginous hairs. Leaflets usually rather thick, 3.5–9(11) × 3–7.5 cm, elliptic or obliquely ovate, rounded or slightly emarginate and mucronulate at the apex, rounded or slightly subcordate at the base, velvety with appressed whitish hairs or appressed pubescent on both surfaces; petiole 1.5–7 cm long; rhachis 0.4–2 cm long; petiolules 4–5 mm long. Inflorescences 2–many-flowered; rhachis 0.3–14 cm long; peduncle 1.3–10 cm long; flowers 2–3 per node, on pedicels 4–10 mm long; bracts and bracteoles 7–10 × 1–3 mm, acute, deciduous. Calyx covered with appressed bristly golden hairs or with a finer ferruginous pubescence; tube 5–7.5(9) mm long; lobes 4–9(12) mm long, narrowly triangular, the upper lip acute. Standard pale maroon to purple or black, 2.5–3.5 cm long and wide, rounded-ovate, glabrous; wings deep maroon, 3.5–4 cm long, with a zone of golden hairs on the outside; keel deep maroon, sometimes whitish below, 3–4.8 cm long, the beak horny, blackish or brownish. Pods 5–7(8) × 1–1.5 cm, oblong, curved, densely covered with brownish very irritant bristles. Seeds pinkish-brown or buff with darker brown mottling, shiny, 8–9 × 7.5 × 3.5 mm, elliptic-oblong, compressed; hilum short with black rim aril and produced into a scale-like appendage.
