Japan Flora: Rather soft, glabrous perennial; culms tufted, about 20 cm. long in terrestrial plants, greatly elongate in water, ascending at base, leafy； leaf-blades thin, flat, glaucous-green, linear, 3-5 cm. long, 2-4 mm. wide, abruptly acuminate; ligules truncate, about 1 mm. long, ciliolate; panicles racemose, 3-6 cm. long, terminal, soon appearing lateral by the elongation of the lateral bud, often reflexed from the base, partly enclosed in the upper­ most sheath, the axis smooth, the branches numerous, simple, ascending, scabrous, about 2.5 cm. long with 1 spikelet slightly below the middle; spikelets nearly sessile, appressed to the branchlet, lanceolate, 4-5 mm. long, gradually acuminate; first glume nearly truncate, about 0.7 mm. long, the second longer, 7-nerved, membranous, pale green, loosely flowered; sterile lemma slightly shorter than the glumes, glabrous; fertile lemma ovate, 1.2 mm. long, smooth. June-Aug. Ponds and wet places.

Honshu, Shikoku, Kyushu. s. Korea and China (?).