Twining herbaceous vine. Leaves trifoliolate; petioles 3-9 cm long, densely pubescent; rachis 1.5-4.5 cm long; leaflets lanceolate-elliptic, rounded to acute at apex, obtuse at base, 9-19 cm long, 4-12 cm wide, glabrous above, sparsely strigillose below. Flowers lavender, in axillary racemes; peduncles ca 10 cm long; rachises to 20 cm long; pedicels to 2 mm long, elongating to 1 cm and thickening greatly in fruit; calyx bilabiate, glabrous, to 13 mm long and 7 mm wide, with the 2 superior teeth +/- rounded and to 5 mm long, the lower 3 teeth acute and to 2 mm long; standard pale lavender, to 2.5 cm long, the margins revolute, strengthening petal; wings and keel white with lavender tips, somewhat shorter than standard, the keel petals fused only briefly below their summit; stamens diadelphous, to 2 cm long, arching into keel petals; filaments united about four-fifths of their length; style +/- equaling the stamens, apparently receptive when pollen is shed; nectaries 2, on either side of the ovary. Legumes to 20 cm long, to 3.5 cm wide, glabrous, brown, the upper margin broad with prominent submarginal ridges and an apical beak; valves at maturity twisting open violently and throwing the seeds; seeds 6-9, vertically oriented, to 2 cm long, 1.5 cm wide, and 1.2 cm thick, brown with dark brown and black markings, buoyant. Croat 4794.