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

Stems erect, to 50 cm, minutely puberulent, hollow when dry. Leaves opposite or occasionally in whorls of 3; petiole 5-7 mm; leaf blade narrowly elliptic, 6-9 × 0.6-1.5 cm, base and apex acuminate; lateral veins ca. 6 pairs, puberulent. Inflorescences axillary, corymbose, or umbel-like; peduncle 0.2-2.2 cm, puberulent. Pedicel 6-10 mm. Sepals triangular, 1.5-2 × 0.5-0.6 mm, puberulent outside, glabrous inside; basal glands 5. Corolla white, rotate; lobes ovate, ca. 4 × 2 mm, obtuse, glabrous outside, puberulent inside. Corona deeply 5-lobed; lobes ovate, slightly shorter than gynostegium. Pollinia elliptic. Stigma head rounded, apex depressed. Fl. Jun.

* In shallow water or water-logged sites; 1100-1200 m. Sichuan.