Scrambling perennial; stems sparsely to moderately hairy, sharply angled, not winged. Lvs ± glabrous to moderately hairy; tendrils usually branched in upper lvs, but often reduced (sometimes to a mucro) and simple in lower lvs; leaflets in 1 pair, lanceolate to narrowly elliptic, acute, (10)-20-30-(45) mm long; veins parallel; stipules lanceolate, usually sagittate, sometimes with only 1 basal lobe, wider than stem, (5)-10-15-(20) mm long. Infl. much > lvs, 2-10-flowered; pedicels 2-4 mm long. Calyx hairy, gibbous at base; calyx teeth somewhat unequal, triangular-subulate; lower teeth usually > or = tube; upper teeth shorter. Corolla yellow, 10-15 mm long. Pod ± glabrous or hairy, dark brownish black, (2)-5-12-seeded, 25-35 mm long; seeds reddish brown, smooth; hilum 1/7-⅕ of circumference.