Vincetoxicum riparium (Tsiang & Zhang) C. Y. Wu & D. Z. Li.

Herbs glabrous throughout. Stems erect, to 60 cm. Lower leaves in whorls of 4, upper leaves opposite, ± sessile; leaf blade linear, 3.5-12 cm × 2-9 mm, papery, base attenuate, decurrent; lateral veins obscure. Inflorescences axillary, shorter than leaves; peduncle 0.7-1.5 cm. Pedicel 4-5 mm. Sepals ovate, ca. 1.5 × 0.7 mm, apex acuminate; basal glands present. Corolla purple, rotate; tube short; lobes oblong, ca. 2 × 1.7 mm, apex acute. Corona deeply 5-lobed, up to as long as gynostegium; lobes ovate, obtuse, with a basal adaxial scar. Anthers square, appendages rounded; pollinia ovoid. Stigma head elevated. Fl. May.

* Grassy areas in upper beds of Yellow River. Henan.