Japan Flora: Rhizomes extremely short, densely tufted; culms very slender, obtusely angled, nearly glabrous, 10- 20 cm. long; leaf-blades capillary, involute, to 1 mm. wide; spike solitary, terminal, androgynous, ovoid, 3-5 mm. long, the stam­inate few-flowered, short, inconspicuous, the bracts wanting; pistillate scales broadly ovate, reddish or dark brown; perigynia slighdy longer than the scales, about 2 mm. long, ascending, elliptic-ovoid, compressed-trigonous, not turgid, with 2 costal nerves, abruptly short-beaked, emarginate at apex; stigmas 3. May-Aug. Wet places in mountains.

Hokkaido, Honshu, Shikoku, Kyushu. Korea.