Erect or rarely decumbent herb 25–120 cm tall, arising from a perennial woody rootstock, usually flowering when the leaves are absent or under-developed; rootstock 14–45 cm long and 7–30 cm in diameter. Stems annual, smooth or slightly ribbed, with sparsely to densely appressed silvery, greyish or ferruginous hairs. Leaves pinnately 3-foliolate; leaflets 2.5–14.5(17) × 1.7–4.2 cm, ovate to elliptic-lanceolate the laterals oblique, all leaflets acute at the apex, mucronulate, cuneate at the base, moderately to densely white or silvery appressed pubescent on both surfaces, often with ferruginous hairs on the veins; petiole 3–10 cm long; rhachis 1–3.5 cm long; petiolules 2–5 mm long; stipules 5–12 × 1–4 mm, lanceolate, caducous. Flowers axillary, solitary, in pairs or in 3–4-flowered fascicles, the late or lack of development of the leaves gives these few-flowered fascicles the appearance of a terminal pseudoraceme; pedicels 3–13 mm long; bracts 2–4 mm long, triangular or lanceolate, upper fascicles with pseudobracts (consisting of under-developed leaves and stipules joined together) 4–7 mm long, forming 3 partially fused or separate lobes; bracts absent; bracteoles 5 mm long, linear. Calyx densely silvery-pubescent; tube 3–5 mm long; lobes 2–6 mm long, triangular, the upper pair fused for almost all of their length. Standard purple, sometimes greenish-brown or yellow outside, or entirely white, 13–29 × 12–20 mm, broadly elliptic to rotund; wings deep purple; keel cream-coloured blushed with purple. Ovary 8–12 mm long, linear-oblong, compressed, appressed pubescent; style 5–10 mm long; stigma minute, terminal, capitate, penicillate. Pods 4.7–7.6 × 0.8–1.1 cm, linear-oblong, densely appressed ferruginous or with golden hairs, minutely glandular, 4–8-seeded. Seeds 6–9 × 4–7 × 2–3 mm, ellipsoid or irregular quadrate, very variable, orange-brown; hilum minute.
