Rhynchospora rugosa (Vahl) Gale

Perennial, with short rhizome; stolons absent. Stems densely tufted, slender, trigonous, smooth, or slightly scaberulous at the top, many-leaved at the base and with some distant cauline leaves, 30-75(-100) cm tall. Leaves shorter than the stems, rigid, flat or canaliculate, long-acuminate, with strong midrib and scaberulous margins, 2-3(-5) mm wide; basal sheaths brown. Inflorescence paniculate, narrow, consisting of 3-4(-6) distant, dense to rather loose corymbiform anthelas, the lateral peduncles compressed, often long-exserted from the sheath, solitary or 2 together; branches very unequal, erect. Bracts erect, about as long as the anthelas in their axils to reaching the next higher anthela, sheathing. Spikelets solitary or in small clusters, shortly peduncled, ovate to ovate-lanceolate, terete, 2-4-flowered, (3-)4-6 mm long. Glumes 5-8, spiral, membranous, shortly mucronate, fuscous. Flowers bisexual, upper one(s) tabescent. Bristles 5-6, from somewhat shorter to distinctly longer than the nut, antrorsely scabrous. Stamens (1-)2(-3); anthers 1-2½ mm long. Style halfway bifid. Style-base conical, glabrous, ½ as long to about as long as and almost as wide as the nut. Nut obovate to broadly obovate, biconvex, dorsiventrally compressed, finely transversely wrinkled, light brown to castaneous, 1½-2 by 1-1¾ mm; epidermal cells longitudinally oblong.

In swampy places, open grasslands, on river-banks, seepage-slopes, from low altitudes up to 2800 m (in New Guinea), in the Malay Peninsula in sandy places near the sea, rarely up to c. 2100 m, in Java between 1600 and 2100 m.