Description from Flora of China
Rhizome short. Culms tufted, 20-60 cm tall, erect, obtusely trigonous, smooth, clothed at base with brown sheaths disintegrating into fibers. Leaves longer than or equaling culm, blades linear, 3-4 mm wide, flat, rather soft. Involucral bracts leaflike, longer than inflorescence. Spicate inflorescence rather dense above, interrupted below, sometimes branched in lowest spike, 3-8 cm; spikes gynaecandrous, ovate or oblong, 5-12 × 3-5 mm, densely flowered. Female glumes whitish, subcordate, green 3-veined costa excurrent into an awn 0.7-1 mm, apex subcuneate. Utricles greenish, longer than glume, suborbicular or broadly ovate, plano-convex, 3.2-3.5 × ca. 2 mm, membranous, smooth, nerveless, base contracted, cuneate, margins winged, scabrous above, apex abruptly contracted into a short beak, orifice 2-toothed. Nutlets greenish, tightly enveloped, broadly ovoid, biconvex, ca. 2.2 × 1.5 mm, apex with a discoid appendage; stigmas 3. Fl. and fr. Apr-Aug.
Wet places along valleys, grassland slopes or forests; 200-1300 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Shaanxi, Shanxi, Sichuan, Zhejiang [Japan, Korea].