Japan Flora: Aquatic perennial herb; corms 3-lobed at base, 1-5 cm. across, densely rooting on inner side of the lobes; leaves tufted, many, slender, usually 20-100 cm. long, 2-5 mm. wide at base, gradually narrowed to an obtusish tip, bright green, subterete in transverse section, the phyllopodia white, nearly square to ovate, 4-15 mm. long, 5-12 mm. wide, thinly membranous on margin, closely imbricate; velum absent; lig­ule thinly membranous, cordate-deltoid, 3-8 mm. long, attenu­ate-acuminate; megaspores white, globose, with 3 commissures in one hemisphere, deeply and subregularly alveolate. Slowly running water of streams and ditches.

Honshu, Shi­koku, Kyushu; rather rare. Korea.