Annual, mostly glabrous. Stem winged. Leaf paripinnately compound, leaflets mostly 2,1-9.5 cm long, 1-10 mm broad, linear or linear-lanceolate; stipules 1-2 cm long, ovate-lanceolate, semi-sagittate; tendrils simple or 3-sect. Inflorescence 1-flowered, peduncle 1-3 cm long, articulated near the middle or apex. Calyx 7-9 mm long, teeth subequal, 2-3 times as long as the tube. Corolla red or reddish purple, 10-16 mm long. Fruit 2-4 cm long, 5-10.5 mm broad, glabrous, upper suture flattened and with 2 narrow lateral keels, 2-6-seeded.