Perennial, with short rhizome and creeping stol-ons. Stems erect, tufted, rather robust, triquetrous at least in the upper part, smooth (somewhat rugulose when dry), not transversely septate, glaucous, 25-60 cm by 2-4 mm. Sheaths thin, rather loose at the apex, pale green to brownish, more or less tinged with purple, obliquely truncate, with a setaceous, up to 4 mm long point at the apex. Spikelet cylindrical, somewhat broader than the stem, terete, obtuse, very densely many-flowered, yellowish, 1½-3½ cm by 3-5 mm. Glumes rather firm, strikingly spirally arranged, very closely packed, (the exposed portion broader than long), tightly appressed, broadly cuneate-obovate to almost quadrate, subtruncate at the apex, faintly many-nerved (the midnerve not very prominent), stramineous to light brown, more or less distinctly brown-zonate within the narrow scarious margins, 2¾-3¾ mm long and about as wide. Bristles 4-6, delicate, from much shorter than to about as long as the nut, with weak both antrorse and retrorse teeth, ferrugineous. Stamens 3; anthers linear, shortly apiculate, 1¼-2 mm. Style 2-3-fid. Nut turgidly biconvex (the margins not ribbed), obovate, without neck and apical annulus (or latter indistinct), shining, at first, stramineous, finally deep brown, 1½-1¾ by c. 1¼ mm; epidermal cells transversely oblong-linear to linear, in c. 20 vertical series on either face, not pitted. Style-base triangular, almost confluent with the nut, c. ⅓ as long and ½ as wide as the nut.
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Perennials. Stolons slender. Culms erect, pale green, tufted, 50-60 cm tall, 3-4 mm thick, firm, 3-angled, without transverse septa and nodes. Leaf sheaths 3 or 4, 3-21 cm, smooth, slightly shiny; basalmost sheath purplish red to dark brown, ± short; cauline sheaths pale red, elongate, mouth obliquely truncate and parted, apex shortly acuminate with a setaceous appendage. Spikelet pale yellow, cylindric, 1.5-3 cm × 5-6 mm, many flowered, apex acute to obtuse. Basalmost glume empty, broadly triangular, amplexicaul for whole spikelet base; fertile glumes densely imbricate, subquadrate, ca. 3 × 3 mm, pale and brownish red puncticulate striate, medially leathery and with a midvein, margin hyaline and minutely brown puncticulate, apex truncate to subtruncate. Perianth bristles 6, reddish purple, as long as or shorter than nutlet, laxly retrorsely spinulose. Stigmas 3. Nutlet pale yellow turning dark brown when mature, obovoid to broadly obovoid, 1.2-1.5 × ca. 1 mm, compressed biconvex, obscurely cancellate with 17-20 rows of transversely oblong epidermal cells, margin narrow, apex not constricted but with an obscure annular thickening; persistent style base conic, basally gradually narrowed, base ca. 1/2 as wide as nutlet. Fl. and fr. Nov-Jan.
In open wet places, pools, swamps, often on clayish soil, at low altitudes (up to 100 m?); almost restricted to brackish or salt localities, sometimes forming extensive, practically pure stands; far inland along salt mudwell near Kesongo (Java, res. Rem-bang).
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