Perennial with stout stolons clothed with ovate, scarious, dark brown scales hardening into a woody rhizome. Stems approximate, robust, spongious, triquetrous with concave sides, almost 3-winged above, smooth, 60-175 cm by up to 12(-15) mm. Lower leaves on the flowering stems reduced to spongious, bladeless greyish black to purplish sheaths, the upper ones with very long (up to 20 cm) sheaths, often laminate but the blades always very short, the uppermost reaching up to halfway the stem; blades of the sterile shoots abruptly acuminate, scabrid at the top, 5-10(-18) mm wide. Inflorescence compound or subdecompound, usually broader than long, sometimes congested, up to 10 by 15 cm. Involucral bracts 3-4, flat, abruptly acuminate, scabrid at the top, much overtopping the inflorescence, shining green above, greyish beneath, the lowest usually erect, up to 30 cm by 8-15 mm, the others patent to reflexed. Primary rays 3-6(-10), very unequal, spreading, slender, smooth, 3-10 cm, secondary ones setaceous, c. 2 cm. Spikes broadly ovoid, with glabrous rachis. Spikelets spicately arranged, 6-12 to the spike, linear, often somewhat curved, subterete, 1-3 cm by 1¼-1¾ cm, 16-20(-40)-flowered; rachilla straight, very narrowly winged, persistent; wings persistent, whitish or yellowish; internodes 3/5-4/5 mm. Glumes chartaceous, ovate to elliptic, obtuse, muticous, not keeled (rounded on the back), indistinctly 5-7-nerved, c. ¼ imbricate, pale fuscous with yellowish margins, when dry crispidly incurved all round, 2-2¼ by 1-1½ mm. Stamens 3; anthers linear, ¾-1 mm. Stigmas 3. Nut trigonous, narrowly oblong, slightly compressed dorsally, hardly apiculate, dark brown to black, 1¾-2 by ½ mm.
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Perennials. Rhizomes long, woody, rarely with thin stolons. Culms 0.5-1.5 m tall, 4-6 mm thick, acutely triquetrous, smooth, base brown and with a bladeless sheath, apical 1 or 2 sheaths with a blade. Leaf blade absent or to 3 cm × 4-8 mm, flat. Involucral bracts 3 or 4, leaflike, to 20 cm, longer to shorter than inflorescence. Inflorescence a simple or compound anthela; rays 6-10, mostly to 9 cm. Spikes broadly ovoid, with 5-10 spikelets; rachis strict, glabrous. Spikelets laxly arranged, linear, 0.8-2.5(-3) cm × ca. 1.5 mm, slightly turgid, spreading, 10-42-flowered; rachilla wings white, narrow, hyaline. Glumes reddish brown but margin yellowish to straw-colored, lax, oblong to elliptic, 2-2.5 mm, papery, inconspicuously 7-9-veined, margin involute at maturity, apex obtuse to rounded. Stamens 3; anthers linear; connective prominent beyond anthers. Style short; stigmas 3, slender. Nutlet blackish brown when mature, narrowly oblong, 1.7-2 mm, almost as long as subtending glume, 3-sided, minutely punctate. Fl. and fr. Jun-Nov.
River margins, ditch margins, water margins, shallow water, ocean beaches, salt-marsh margins, fields (usually cultivated). The plant is an abundant colonizer on mud flats in estuaries and on sandy shores.
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In moist localities, usually within the influence of salt or brackish water, a coloniser along muddy river-mouths, on mud flats, sandy foreshores covered by springtides; often abundant.
Uses. The stems are often used for tying purposes and for making mats, baskets, and hats; the manufacture of slippers of this material is carried on to a considerable extent in some towns of Bulacan Prov., Luzon (see BROWN, l.c.). In Pekalongan (Central Java) the stems are used by the fishermen; pieces of the stems are plaited in ropes which are brought into the sea. The fry, attracted by the stems, is caught and then planted in fish-ponds. See VAN STEENIS Trop. Natuur 29 1940 20 , fig.
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