Japan Flora: Somewhat resembling No. 3; culms 10-30 cm. long; leaves very slender, 1-1.5 mm. wide; inflorescence of 1 or 2 sessile spikes bearing several spikelets; spikelets oblong, mostly flattened, 8-15 mm. long, pale to partly sanguineous; scales narrow-ovate, about 3 mm. long, obtuse, entire, 3-nerved; achenes 1/3 as long as the scale, obovate-orbicular, biconvex, dark brown; stigmas 2. Aug.-Oct.
Honshu (Aomori); rare. Bonin Isis., Korea, Northeast China, Amur, centr. Asia, India, and Malaysia.