Japan Flora: Perennial herb; rhizomes short; stolons ab­sent; leaves rosulate, linear or linear-oblanceolate, 10-15 cm. long, 5-8 mm. wide, acute to acuminate with an obtuse dp, gradually narrowed to a sheath at base, petioles indistinct; scapes 10-25 cm. long, few-flowered; flowers in racemes; pistil- late flower solitary, sessile on the lowest node, the staminate flowers few, on pedicels 10-30 mm. long; petals rounded- obovate, &-10 mm. long; achenes narrowly obovate, about 3 mm. long, compressed, with a broad wing.  June-Oct. Muddy places, paddy fields, and ponds.

Honshu (exclusive of northernmost distr.), Shikoku, Kyushu. Korea, Formosa, and China.