Robust climbers, with tuberous roots. Stems to 8 m, woody at base, hirsute with yellowish hairs in all parts. Stipules dorsifixed, ovate-oblong, striate; stipels linear-lanceolate, equal to petiolules or longer; leaflets 3-lobed, rarely entire, terminal one broadly ovate, 7-15(-19) × 5-12(-18) cm, apex acuminate, lateral ones obliquely ovate, smaller, with yellowish adpressed hairs adaxially, more densely hairy abaxially. Racemes 15-30 cm. Flowers 2 or 3 aggregated at nodes. Bracts linear-lanceolate to linear, shorter or longer than bracteoles, caducous; bracteoles ovate, less than 2 mm. Calyx 7-20 mm, villous with yellow-brown hairs; lobes lanceolate, acuminate, slightly longer than tube. Corolla purple; standard obovate, 8-18 mm, auriculate and with yellow callosities at base, shortly clawed; wings falcate, narrower than keel, base with linear auricles; keel falcate-oblong, with very small and acute auricles. Vexillary stamen free in upper part. Ovary linear, hairy. Legumes long elliptic, 4-14 cm × 6-13 mm, flattened, brown hirsute. Fl. Jul-Oct, fr. Oct-Dec.