Erect herb 60–180 cm tall, arising from a perennial woody rootstock. Stems annual, ribbed, pubescent or with lines of appressed hairs along the ribs and pubescent in between. Leaves pinnately 3-foliolate; leaflets 1.8–7.2(11) × 1.6–4.2(5) cm, narrowly oblong-elliptic, subacute or rounded at the apex, mucronate and with an apical tuft of hairs, rounded at the base, appressed pubescent on both surfaces, more densely so on the veins of the lower surface, or sparsely pilose to velvety, discolorous; petiole 0.5–7 cm long; rhachis 0.3–5 cm long; petiolules 1.5–3 mm long; stipules 4–12 × 1–3 mm, lanceolate, striate, persistent. Flowers axillary, solitary, in pairs or in 3–4-flowered fascicles, the late or lack of development of the leaves giving these few-flowered fascicles the appearance of a terminal pseudoraceme; pedicels 5–10 mm long; bracts absent; bracteoles 1–2 mm long, lanceolate, persistent. Calyx pubescent; tube 3–5 mm long; lobes 2–5 mm long, triangular, upper pair completely fused. Standard purple, crimson inside at the base, greenish outside, sometimes mostly green or yellow, 11–14 × 10–12 mm, round or nearly so; wings mostly mauve or blue; keel green or cream-coloured. Ovary 6–9 mm long, linear-oblong, compressed, tomentose; style 3–5 mm long, stigma minute, terminal, capitate, penicillate. Pods 2.5–4.3 cm × 4–10 mm, oblanceolate, appressed pubescent with mixed short and very short hairs, 5–6-seeded. Seeds reddish-brown speckled black, 4–5 × 4–5 × 1–2 mm, square, compressed.
