Japan Flora: Perennial; rhizomes loosely tufted, long-creeping; leaves linear, plicate, 3-6 mm. wide, to 25 cm. long, rather rigid; basal sheaths short-bladed, light purple-brown to red- brown; culms 20-30 cm. long, smooth; spikelets 3-6, the terminal staminate, linear-clavate, brownish, 2-3 cm. long, the lateral pistillate or sometimes androgynous, oblong-cylindrical, 10-25 mm. long, about 7 mm. wide, densely many-flowered, peduncled, with sheathing bracts; pistillate scales oblong- elliptic to oblong-ovate, pale with brownish margins; perigynia erect-spreading, oblanceolate or linear-oblong, 4.8-53 mm. long, trigonous, smooth, thinly membranous, nearly nerve­less except for lateral 2 keels, the beak long, with a bidentate mouth; achenes tightly inclosed; stigmas 3. Wet rocks along streams.

Honshu (Suruga Prov.); rare