4. Rhynchospora rugosa (Vahl) Gale subsp. brownii (Roemer & Schultes) T. Koyama, Stearn & L. H. J. Williams in H. Hara, Enum. Fl. Pl. Nepal. 1: 118. 1978.
白喙刺子莞 bai hui ci zi guan
Rhynchospora brownii Roemer & Schultes, Syst. Veg. 2: 86. 1817; R. glauca Vahl var. condensata Kükenthal; R. rugosa var. condensata (Kükenthal) T. Koyama.
Perennials. Rhizomes very short. Culms tufted, erect, 30-55(-90) cm tall, slender, 3-angled, smooth but apically usually scabrous. Leaves basal and a few cauline and distant, shorter than culm; sheath brown, closed, 2.6-6 cm, glabrous, with very short ligule at mouth; leaf blade narrowly linear, 1.5-3 mm wide, flat or canaliculate, margin and abaxial midvein scabrous, apex long acuminate. Involucral bracts leaflike, basal ones sheathing, apicalmost sheathless. Inflorescences paniculate, narrow, consisting of 3 or 4 dense to ± lax corymbiform anthelae; lateral peduncles solitary or 2 together, compressed, often long exserted from sheaths; rays very unequal, erect; raylets setaceous. Spikelets dark brown, ellipsoid to subovoid, 3-4.5 mm, 3- or 4-flowered, base ± obtuse, apex acute. Glumes 7 or 8, elliptic-ovate, ovate, or broadly ovate; basal 3 or 4 glumes empty. Perianth bristles 6, slightly shorter than nutlet, unequal, antrorsely scabrous. Stamens (1-)3; filaments longer than nutlet and style base. Ovary obovoid; style filiform; stigmas 2, as long as style. Nutlet pale rust-colored, broadly ellipsoid-obovoid, ca. 1.7 mm, biconvex, finely transversely wrinkled with longitudinal epidermal cell; persistent style base broadly conic, shorter than nutlet. Fl. and fr. Jun-Oct. 2n = 36.
Swamps, moist river margins; 1000-2400 m. Fujian, Guangdong, Guangxi, Guizhou, Hunan, Jiangxi, Sichuan, Taiwan, Yunnan, Zhejiang [India, Indonesia, Japan, Malaysia, Nepal, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; Africa, Australia, Europe, Indian Ocean islands, Madagascar, Pacific islands].
Rhynchospora rugosa subsp. rugosa occurs in tropical America and South America.