Japan Flora: Rhizomes nearly absent; culms filiform to capillary, 3-10 cm. long, sulcate, deep green, the sheaths 2-10 mm. long, often partially reddish; spikelets few-flowered, nar­rowly ovoid to broadly lanceolate, 2-4 mm. long, compressed, acute, pale green and usually pardy sanguineous; scales nar­rowly ovate, hyaline; achenes narrowly obovate, 1 mm. long, raised-reticulate with several longitudinal ribs and very many transverse lines, the style base depressed, triangular，conical, the bristles 3-4a unequal, much longer than the achene.  June-Sept. Common in wet places especially in paddy fields.

Hokkaido, Honshu, Shikoku, Kyushu. e. Siberia, Man­churia, Korea, China, Ryukyus, and Formosa.