Japan Flora: Stems filiform, yellowish, much branched; leaves all submersed, filiform, 3-10 cm. long, 0.5-1 mm. wide, entire and acute at apex; stipules 1-2 cm. long, whitish, membranous, adnate to the base of the leaves from three-fourths to six- sevenths of their length; peduncles slender, 2-10 cm. long; spikes remotely few-flowered, 2-4 cm. long; nutlets broadly obovate, 3-3.5 mm. long, usually rounded and entire on back. June~Oct. Ponds and shallow rivers, especially near sea shores.
Hokkaido, Honshu, Shikoku, Kyushu. Eurasia, N. America, Africa, and Australia.