Stratiotes alismoides Linnaeus, Sp. Pl. 1: 535. 1753; Damasonium alismoides (Linnaeus) R. Brown; D. indicum Willdenow, nom. illeg. superfl.; Ottelia alismoides f. oryzetorum Komarov; O. condorensis Gagnepain; O. dioecia S. Z. Yan; O. indica Planchon ex Dalzell & A. Gibson, nom. illeg. superfl.; O. japonica Miquel; S. quinquealatus Stokes, nom. illeg. superfl.

Petiole varying greatly in length according to depth of water; leaf blade wholly submerged, varying greatly in shape and size, usually broadly ovate, ovate-elliptic, suborbicular, cordate, or sometimes lanceolate, ca. 20 × 18 cm or more, membranous. Flowers bisexual or plants occasionally dioecious-polygamous. Spathe 2.5-4 × 1.5-2.5 cm, 2- or 3-lobed at apex, with 3-6 longitudinal wings. Flowers solitary, sessile. Petals white, slightly purple, or bluish. Stamens 3-9(-12); filaments glandular hairy; anthers narrowly oblong, 3-4 mm. Ovary subglobose, with 3-9(or 10) carpels; styles 6-10, deeply 2-lobed. Fruit 2-5 × 0.8-1.8 cm. Seeds fusiform, 1-2 mm, densely hairy. Fl. and fr. Apr-Oct. 2n = 44.

Still or running water. Anhui, Fujian, Guangdong, Guangxi, Guizhou, NW Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Sichuan, Taiwan, Yunnan, Zhejiang [Cambodia, India, Indonesia, Japan (including Ryukyu Islands), Korea, Laos, Malaysia, Myanmar, Nepal, New Guinea, Philippines, Thailand, Sri Lanka, Vietnam; Africa, Australia; introduced in North America].