Chaetospora calostachya R. Brown, Prodr. 233. 1810.

Perennials. Rhizomes short. Culms tufted, erect, (30-)70-90 cm tall, obtusely 3-angled to subterete, sulcate, smooth. Leaves basal and cauline; sheath blackish purple; leaf blade linear, 30-75 cm × 1-2 mm, rigid, 3-veined on abaxial surface, margin scaberulose, apex acute. Involucral bracts leaflike; sheaths black purplish red to reddish black, 1.5-2.5 cm, terete; mouth pale, oblique, membranous. Inflorescences racemose, to 50 cm, very lax, with 2 or 3 very distant fascicles of branches; peduncle 10-15 cm, glabrous; branches solitary or 2(or 3) together, erect, ca. 12.5 cm, unequal, compressed, scaberulose on angles, each bearing 1(-3) spikelets. Spikelets chestnut-brown, oblong to narrowly ovoid, 3-5-flowered, apex acute to acuminate. Glumes distichous, narrowly lanceolate, basal 5 and apical 1 or 2 empty; fertile glumes to 1.5 cm; sterile glumes ca. 0.4 cm, leathery, densely ciliate especially toward apex, keel green. Perianth bristles 4-7, white, ca. 1/2 as long as nutlet, antrorsely scabrous on apical part, easily caducous. Stamens 3; anthers linear, caducous. Style slender, apical half ciliate; stigmas 3, papillate. Nutlet grayish brown, obovoid, 3-sided, reticulately wrinkled, glabrous, base attenuate, apex obscurely beaked. Fl. and fr. Jul-Sep.

Slopes, hilltops; ca. 600 m. Guangdong, S Guangxi, Hainan (Wenchang) [Indonesia, Japan (Ryukyu Islands), Malaysia, Papua New Guinea, Thailand, Vietnam; Australia, Pacific islands].