Japan Flora: Stems often elongate; floating leaves thickish, long-petiolate, ovate-oblong to elliptic, 5-10 cm. long, 2.5—5 cm. wide, many-nerved, entire, apiculate, rounded at base, the submersed leaves semi terete, slenderly linear, the stipules 5-8 cm. long, membranous and many­nerved; peduncles 5-10 cm. long, as thick as the stem through­out, bearing densely flowered spikes 4-6 cm. long; nutlets broadly ovate, 35-4 mm. long, nearly entire on dorsal ridge. Apr.-Aug. Ponds and shallow rivers.

Hokkaido, Hon­shu, Shikoku, Kyushu.  Widely distributed in temperate regions.