Japan Flora: Culms tufted, 10-30 cm. long, flac­cid, rather flat, glabrous; leaves shorter than the culm, flaccid, flat, 1.5-2.5 mm. wide, abruptly acute,  glabrous, the sheaths distichous, keeled, compressed, minutely ciliate along the dorsal margin of the mouth; inflorescence umbelliform, compound, with many spikelets, the bracts 2 or 3，linear, rather short; spikelets rather loosely arranged, lanceolate, angled, 7- to 16-flowered, 3-6 mm. long, 1.5 mm. wide, brownish red; scales membranous, narrowly ovate, 1.5-2 mm. long, acute, keeled; achenes 0.7 mm. long, whitish, with transversely ob­long reticulations; anthers 0.2 mm. long. July-Oct. Com­mon in wet places in lowlands.

Hokkaido, Honshu, Shikoku, Kyushu. Korea, Ryukyus, and N. America.