Scirpus mucronatus L., Sp. Pl. 1: 50. 1753; Kern in van Steenis (ed.), Fl. Malesiana, 7,3: fig. 30. 1974.

Perennial with short rhizome, or annual, 30-70 cm, forming small tufts. Root system small. Stem 2-5 mm diam., sharply trigonous, green or greyish green, edges smooth. Sheaths two, lower up to 25 mm, upper up to 10 cm or more, green, mouth oblique, margin widely scarious; ligule present; blades reduced to mucro. Inflorescence congested to sphaerical group of 6-15, occasionally up to 1-3, sessile spikes, up to c. 20 mm diam.; lowest bract conspicuous, green, up to more than 10 cm, at first upright, later reflexed, sharply trigonous, smooth, adaxial side concave, apex obtuse. Spikes 7-18 x 4-5 mm, ovoid; glumes tightly imbricating, 2.7-3.5 mm, cymbiform, mid-nerve smooth, extending into short mucro, sides many-nerved, grey-brown, often with reddish tint, margins scarious, slightly recurved, fringed. Perianth bristles 6, slightly longer than fruit, brown; stamens 3, anther c. 1 mm; stigmas 3. Nut 1.7-2 x 1.4-1.5 mm, obovoid, apiculate, trigonous, almost plano-convex, shallowly transversely rugulose, glossy, blackish brown.

Fl. Per.: September.

Type: ”Habitat in Angliae, Helvetiae, Virginiae stagnis maritimis”.

Rice fields; Distribution: From C. and S. Europe to Japan and Malesia, Africa, Madagascar, India, Australia; reported as rice weed from California.

Koyama (1978) distinguishes in Nepal Schoenoplectus mucronatus subsp. robustus occurring in SE Asia in area from Japan to China, India and Malesia. Kern in Fl. Malesiana (1974), besides Scirpus mucronatus subsp. mucronatus, accepts subsp. clemensii Kük., thus restricted to Malaysia. Material seen is considered to belong to subsp. mucronatus.