Scirpus supinus L., Sp. Pl. 1: 49. 1753. Isolepis supina (L.) R. Br., Prodr. Fl. Nov. Holl. 1: 77. 1810; Schoenoplectus melanospermus (C.A. Mey.) Grossh., Fl. Kavk., ed. 1, 1: 146. 1928. Scirpus melanospermus C.A. Mey. in Mém. Acad. Imp. Sci. St.-Petersbourg, sér. 6, 1: 199. tab.2. 1831; Madalski, Fl. Polon. Terr. Adiac. Iconogr. 3(1): 257. 1979.

Annual, 5-30 cm, forming tufts. Root system fibrous, small. Stem 0.8-2 mm diam., terete or distal parts obscurely trigonous, grooved, green or greyish green, smooth. Sheaths up to 65 mm, 2-3, lowest short, ephemeral, bearing an occasional flower in its axil, upper longer, mouth oblique, margin widely scarious; ligule up to 0.8 mm, scarious; blades reduced to mucro or, in uppermost sheath, most often green, up to 50 mm. Inflorescence 7-20 mm diam., congested to spherical group of (1-)3-15 spikes, sessile or occasionally one or a few spikes pedunculate; lowest bract 2-16 cm, terete, apex rather obtuse, smooth, other bracts seldom green and longer than their spike. Spikes 5-12 mm, ovoid; glumes rather tightly imbricating, 2.1-2.7 mm, cymbiform, towards apex slightly keeled, smooth, mucro c. 0.3 mm, sides obscurely nerved, brown or colourless, scarious, margin smooth or minutely fringed. Perianth bristles reduced, 3-4 occasionally elongated, unequal, longest shorter than nut; stamens 3, anther 0.5-0.7 mm; stigmas 3. Nut 1.3-1.6 x 1-1.3 mm, widely obovoid, apiculate, trigonous, surface conspicuously transversely rugulose with very fine longitudinal striations, glossy, black brown.

Fl. Per.: July - August.

Lectotype: "Habitat Parisiis"; in Herb. Tournefort 5117 (P), selected by Raynal in Adansonia 16: 145. 1976. Reported from Sind by Cooke, l.c. 916. 1908. Report from Pakistan, as well as the specimens seen by the author from Iran, Baluchistan, represent disjunctions and need further study.

On wet disturbed ground by standing water, at pools, in rice fields; Distribution: Europe, N. Africa, Turkey, Caucasus, S Siberia, Kazakhstan, Iran, Pakistan to Far East.

The description is based on specimens from S. Russia and the Balkan peninsula. Egorova (1976; Novit. Syst. Pl. Vasc. 28: 5-21. 1991) considers S. supinus and S. melanospermus as distinct species, based on presence/absence of perianth bristles. Raynal (l.c. 1976) united them as one species with wide distribution in Old World.