Japan Flora: Small dark green aquatic herb; corms 5-15 mm. across, 2-lobed at base, densely rooting on inner side of the lobes; leaves 10-30, tufted, erect or ascending, subulate, 5-20 cm. long, 1.5-2.5 mm. wide near the middle, gradually narrowed to an obtusish tip, subterete, with a narrow flat face inside, the phyllopodia deltoid, 4-7 mm. long, 5-10 mm. wide, closely imbricate, membranous on mar­gin, white; velum orbicular to elliptic with a suborbicular to elliptic opening at base extending to the middle; ligule cordate- suborbicular or broadly cordate; megaspores white, globose, marked in one hemisphere with 3 commissures, densely spiny. Shallow water of lakes and ponds.

Hokkaido, Honshu (centr. and n. distr.); rare. s. Sakhalin.