Japan Flora: Stems slender and much branched; leaves all submersed, lin­ear, 2-6 cm. long, 2-3 mm. wide, finely serrulate, 3-nerved and faintly nervulate, becoming broadly obtuse to rounded at apex, briefly adnate to the stipules at base; stipules about 10 mm. long, membranous; peduncles 1-3 cm. long; spikes few­flowered; nudets broadly ovate-elliptic, about 3 mm. long, with an acute keel; style short. May-Sept. Ponds and shallow rivers.

Hokkaido, Honshu, Kyushu. e. Siberia, Korea, and Manchuria.