Scrambling annual; stems glabrous, angled, broadly winged. Lvs glabrous; tendril branched in upper lvs, sometimes reduced and simple in lower lvs; leaflets in 1 pair, narrowly to broadly elliptic, acute to obtuse, 20-70 mm long; veins parallel; stipules lanceolate to ovate, usually with 1 basal lobe and about as wide as stem, (10)-15-30 mm long. Infl. about = or somewhat > lvs, 1-3-flowered; pedicels 4-8 mm long. Calyx glabrous, somewhat gibbous at base; calyx teeth unequal, narrowly to broadly triangular, < tube. Corolla usually purple, sometimes crimson, pink or white, 20-35 mm long. Pod glabrous, brown, 5-8-seeded, 70-110 mm long; seeds reddish brown or mottled brown, smooth; hilum ⅙-⅕ of circumference.