Description from Flora of China
Hypoporum pergracile Nees, Edinburgh New Philos. J. 17: 267. 1834.
Annuals. Rhizomes absent. Culms tufted, erect, 11-30 cm tall, ca. 0.5 mm wide, 3-angled, sulcate, glabrous. Leaves basal and cauline, sheathing; contraligule rounded to obtuse; leaf blade capillary, ca. 1 mm wide. Involucral bracts setaceous, basal one to 0.6 cm and shorter than spikelet cluster; bractlets glumelike. Inflorescences spicate, 2.5-8.5 cm, formed by clusters of 2 or 3 spikelets each separated by 2-17 mm. Spikelets mostly bisexual, ovoid, 3-4 mm, rarely basal one unisexual with a single male flower. Glumes ovate, keeled, both sides of midvein membranous with reddish brown lines, apex mucronate; basal 2 glumes empty; middle glume with a female flower; apical 1 or 2 glumes with a male flower. Male flowers: stamens 3; connective apex protruding, forming a thin tip. Female flowers: stigmas 3. Disk obscure. Nutlet white, subspherical, ca. 1 mm in diam., slightly 3-sided, transversely rugose, base with a brown stalk, apex tipped. Fl. and fr. Aug-Oct. 2n = 10.
Alpine grasslands, valley pastures; 1200-4000 m. Guangdong, Guangxi, Jiangsu, E Xizang, Yunnan [Bangladesh, Cambodia, India, Indonesia, Kashmir, Korea, Laos, Myanmar, Nepal, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; tropical Africa, NE Australia].