Menyanthes hydrophylla Loureiro, Fl. Cochinch. 1: 105. 1790.

Stems 10-30 cm, rooting from nodes. Leaves few per node; petiole 4-10 cm, slender; leaf blade cordate, 1-6 × 1-4(-5) cm, submembranous, veins indistinct. Flowers 2-10 per node, 5merous, homostylous. Pedicel 2-6 cm, slender. Calyx 4-5 mm, lobed to near base; lobes narrowly oblong, apex acute. Corolla white, campanulate, 7-8 mm, lobed to middle, tube 4-5 mm; lobes 3-4 mm, margin laciniate, apex emarginate. Filaments absent; anthers triangular, ca. 1 mm. Style very short. Capsules globose, ca. 3 mm in diam., 6-10- seeded. Seeds brown, globose, ca. 1 mm in diam.; seed coat spinescent. Fl. and fr. Aug-Sep.

The epithet hydrophyllum is a noun in apposition.

Standing water. Guangdong, Guangxi, Hainan [India, Laos, Thailand, Vietnam].