Rhizome short, indurate. Plants wholly ferruginous puncticulate. Culms tufted, 20-80 cm tall, trigonous, scabrous above, clothed with ferruginous-brown sheaths at base. Leaves shorter than culm, loosely subtending culm, blades linear, 3-5 mm wide, flat, apex long acuminate; membranous side of leaf sheath transversely wrinkled, truncate at apex. Lower 1 or 2 involucral bracts leaflike, upper ones setaceous. Spicate inflorescence cylindric, 5-8 cm; spikes numerous, dense, androgynous, ovate, 5-12 × 4-6 mm. Female glumes pale ferruginous, ovate, 2.2-3 mm, ferruginous puncticulate, apex subacute, awned. Utricles pale yellow or pale green, longer than glume, lanceolate-ovate or oblong-ovate, plano-convex, 3.5-4 × ca. 1 mm, membranous, ferruginous puncticulate, many veined on both faces, base rounded, not spongy, shortly stipitate, margins wingless, apex gradually narrowed into a smooth long beak, orifice 2-toothed. Nutlets loosely enveloped, elliptic or ovate-elliptic, plano-convex, 1-1.2 mm; style long, base not thickened. Fl. and fr. Jun-Jul. 2n = 76-80.
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