Japan Flora: Rhizomes short; culms tufted, 40- 60 cm. long, obtusely angled, smooth; leaf-blades ).5-25 mm. wide, flat; inflorescence ovate-cylindric, 2-6 cm. long, dense, with scalelike bracts, the spikes androgynous, ovate-orbicular, 3-6 mm. long; scales pale, oval; perigynia longer than the scales, spreading, 35-4 mm. long, ovate-conic, many-nerved, glaucous, greenish yellow, lustrous, planoconvex, with several large tubercles on the back, narrowly winged and scabrous on the margins, gradually beaked, the tip 2-toothed; achenes loosely inclosed, biconvex; style bifid. May.

Honshu (Chugoku Distr.); rare. Korea and China.