Cyperus dubius Rottb.

Perennial with short rhizome; stolons wanting. Stems densely tufted, rather slender, triquetrous, smooth, (5-)15-45 cm by 1-2(-3) mm, the base apparently bulbous by the striate, turgid, scarious, pale to brown lower sheaths, finally surrounded by their fibrous remains. Leaves weak, flat, gradually acuminate, slightly scaberulous at the top, (1½-)2-5 mm wide. Inflorescence contracted into a very dense, lobed head consisting of 1-6 confluent spikes, broadly ovoid, subglobose or suboblong, 1-2 cm long and wide. Involucral bracts 3-5, weak, patent to reflexed, up to 30 cm. Spikelets numerous, patent, ovate to oblong-lanceolate, acute, subterete, somewhat turgid, oblique at the base, falling off as a whole, (2-)3-6-flowered, 4-7 by (1-)1½-2¼ mm; rachilla nearly straight, conspicuously winged; wings lanceolate, persistent, whitish hyaline. Glumes subcoriaceous, broadly ovate to lanceolate, obtusish, muticous, 15-19-nerved over the whole breadth, slightly keeled, with at first whitish, finally stramineous to brown sides and hyaline margins, c. ⅔ imbricate, 3-4 by 1½-3 mm. Stamens 3; anthers oblong-linear, 1-1½ mm. Stigmas 3. Nut trigonous, ellipsoid or slightly oblong-ellipsoid, apiculate, castaneous, 1.6-2½ by ¾ mm.

In W. Malesia only near the sea, usually on sandy beaches in fully exposed places, acting as a sand binder; the plant is probably sea-dispersed; see RIDLEY Disp. 1930 327 . In Luzon on wet banks in ravines and on dry, open, rocky slopes at low altitudes.