Herbs twining. Stems terete, striate, glabrous. Petiole 2-7 cm, glabrous; leaf blade narrowly deltate to deltate-cordate, 3-13 × 3-10 cm, papery, both surfaces glabrous, veins palmate, 2-3 pairs from base, base cordate, sinus ca. 1.5 cm deep, apex acute or obtuse. Racemes in axils of leafy shoots, 2-8-flowered, nearly fasciculate. Pedicel ascending, 1-2 cm, glabrous; bractlets ovate, ca. 1.5 × 1 cm. Calyx yellow-green with purple veins; tube rectilinear or slightly curved, abaxially glabrous; utricle globose, ca. 6 mm in diam., sessile; tube ca. 14 × 3 mm; limb unilateral, ligulate, ovate-lanceolate, ca. 3.5 × 1 cm, apex long acuminate with twisted cauda 1-3 cm. Anthers elliptic, ca. 0.5 mm. Gynostemium 6-lobed. Capsule broadly obovoid to ellipsoid-obovoid, 3-6.5 × 2.5-4 cm, dehiscing acropetally. Seeds deltoid-cordiform, 3-5 × 3-5 mm, with membranous wing. Fl. May-Jul, fr. Aug-Oct.

Thickets, mountain slopes, valleys; 500-1200 m. Fujian, Gansu, Hebei, Heilongjiang, Henan, Jilin, Liaoning, Shaanxi, Shandong, Shanxi [Japan, Korea, Russia (Siberia)].