Description from Flora of China
Carex dispalata var. costata Kükenthal; C. pollens C. B. Clarke; C. pollens var. angustior C. B. Clarke.
Rhizome thick, ligneous, with elongate and thick stolons. Culms 40-80 cm tall, acutely triquetrous, medium thick, slightly scabrous on upper angles, red-brown and bladeless sheathed, sheaths eventually disintegrating into reticulate fibers on one side. Leaves nearly equaling culm, blades 4-8 mm wide, flat, with 2 distinct lateral veins, smooth on both surfaces, scabrous on upper margins, lower leaves long sheathed, upper leaves nearly not sheathed. Involucral bracts leaflike, lower involucral bracts longer than subtending spike, upper ones shorter than spike, not sheathed. Spikes 4-6, approximate, usually ± contiguous at upper part of culm; terminal spike male, cylindric, 4-6 cm, pedunculate; lateral spikes female, cylindric, 3-9 cm, densely many flowered, sometimes with several male flowers at apex, subsessile or shortly pedunculate at lowest spike. Female glumes red-brown on sides, yellowish green at middle, ovate-lanceolate or lanceolate, ca. 3 mm, membranous, 3-veined, apex acuminate, muticous or mucronate. Utricles brownish green, slightly longer than glume, obliquely patent or nearly horizontally patent at maturity, ovate, slightly inflated trigonous, 3-4 mm, thickly papery, glabrous, transversely rugose, indistinctly few veined, base rounded, stipitate, apex abruptly contracted into a medium-sized to long beak, beak slightly recurved, purple-red at top, obliquely truncate or emarginate at orifice. Nutlets stramineous, slightly loosely enveloped, obovate or elliptic-obovate, trigonous, ca. 2 mm, apex mucronate; stigmas 3. Fl. and fr. May-Jul.
Ditches, marshes, wet areas; 500-2900 m. Anhui, Hebei, Jiangsu, Jilin, Liaoning, Nei Mongol, Shaanxi, Shanxi, Zhejiang [Japan, Korea].