A perennial twiner; root tuberous; young branches grey pubescent. Leaf pinnately trifoliolate, petiole 10-20 cm long; leaflets 12.5-20.0 cm long, 11.0-17.5 cm broad, the terminal leaflet broadly ovate, equal sided, acuminate, the lateral leaflet ovate-oblong, very oblique, acuminate, silky pubescent below, glabrescent above; stipels small; stipules c. 5 mm long. Inflorescence an axillary or terminal raceme or panicle. Pedicel 2-3 mm long. Bracts and bracteoles small. Calyx 6-8 mm long, densely silky, teeth shorter than the tube, the 2 upper teeth connate. Corolla blue. Vexillum c. 12.5 mm long and broad, auricled at the base. Fruit 5-7.5 cm long, constricted between the seeds, densely pilose, hairs brown, silky, 3-6-seeded.