Japan Flora: Slender glabrous perennial; culms ascending, long-creeping at base, 20-40 cm. long; leaf-blades 5-10 cm. long, 1.5-3 mm. wide, flat, thin, glaucescent; ligules narrowly deltoid, 3-6 mm. long; panicles narrowly ovate, rather loose and open, 6-10 cm. long, the branches 2- to 4-nate, scabrous, slender, ascending; spikelets narrowly oblong, 4-6 mm. long, 3- or 4-flowered, pale green; glumes broadly lan­ceolate, rather obtuse, the 1st 1-1.2 mm. long, the 2d with a pair of short lateral nerves, about 15 mm. long; lemmas nar­rowly ovate, 2-2.5 mm. long, 7-nerved, scaberulous. July-Aug. Ponds.

Hokkaido, Honshu (Kamikochi in Shinano); rare. s. Kuriles, Sakhalin, Ussuri, and Kamchatka.