Description from Flora of China
Carex chlorostachys D. Don ex Tilloch & Taylor, Philos. Mag. J. 62: 455. 1823, not Steven (1813); C. alopecuroides D. Don ex Tilloch & Taylor var. chlorostachya C. B. Clarke; C. japonica Thunberg subsp. chlorostachya (C. B. Clarke) T. Koyama; C. japonica var. chlorostachya (C. B. Clarke) Kükenthal; C. sasakii Hayata.
Rhizome short, with slender stolons. Culms 30-60 cm tall, rather thick, compressed triquetrous, scabrous on angles, with brownish yellow sheaths at base, sheaths sometimes disintegrating into fibers. Leaves slightly longer than or nearly equaling culm, blades 5-12 mm wide, flat, rather soft, distinctly 2-veined laterally on upper surface, scabrous on upper margins, sheathed. Involucral bracts leaflike, upper ones linear, longer than subtending spike, not sheathed. Spikes 2-6, lowest 1 or 2 spikes remote, upper ones rather congregate at top of culm; terminal spike male, linear-cylindric, 3-7.5 cm, pedunculate; lateral spikes female, sometimes with several male flowers at apex, cylindric, 3-7 cm, densely many flowered, lower ones shortly pedunculate, upper ones nearly sessile. Female glumes pale yellow or partly pale brown, ovate-lanceolate, ca. 2.5 mm, membranous, green 1-veined, apex mucronate. Utricles greenish yellow, eventually horizontally patent, longer than glume, oblong-ovate, slightly inflated trigonous, 3.5-4 mm, membranous, obscurely several veined, base broadly cuneate or subrounded, apex attenuate into a straight and short beak, orifice shortly 2-toothed. Nutlets dark yellow, loosely enveloped, obovate, trigonous, ca. 1.8 mm, apex mucronate; style base not thickened; stigmas 3, slender, persistent. Fl. and fr. Apr-Oct.
Streamsides, ditch sides, forests, among shrubs, wet places in grasslands; 500-3000 m. Fujian, Guangdong, Guangxi, Hubei, Jiangsu, Shaanxi, Sichuan, Taiwan, Yunnan, Zhejiang [Japan, Korea, Nepal, Philippines].