21. Cyperus serotinus Rottb., Descr. Pl. Rar. 18. 1772; R. R. Stewart, l.c. 92; Kukkonen in Rech.f., 111.
Juncellus serotinus (Rottb.) C. B. Clarke, in Hook. f., Fl. Brit. Ind., 6: 594. 1893. Chlorocyperus serotinus (Rottb.) Palla, Allg. Bot. Zeitschr. 6: 201. 1900. Duval-Jouvea serotina (Rottb.) Palla in W.D.J. Koch, Syn. deutsch. schweiz. Fl., ed. 3, 3: 2556. 1903; C. monti L. fil., Suppl. Pl.: 102. 1781. Pycreus monti (L. f.) Reichenb. in Mössler, Handb. Gewächskunde, Ed. 2, p. 1802. 1829; Kükenthal, in Engler, Pflanzenr., IV.20, 101: fig. 36. 1936. Ovczinnikov, Fl. Tadjik. SSR, 2: tab. 1, figs. 5-7. 1963.
Perennial, 40-60 cm. Rhizome short, emitting creeping stolons, 2-3 mm diam., covered by brown scales, shorter than internodes. Stem 3.5-5 mm diam., sharply trigonous, grey green, smooth. Leaves equalling stem; sheaths up to 15 cm, all with blades, green or grey green, often with some reddish tint, mouth margin almost straight; blades up to 60 cm, 4-8 mm wide, flat or folded, keeled, margins and keel smooth, apex long-attenuate, scabrous. Inflorescence a compound anthelodium, 6-20 cm; bracts 2-4 foliose, up to 50 cm; primary branches 4-7, up to 16 cm; secondary anthelodia 25-50 mm, conical; secondary branches to 10 mm; cluster of spikes rounded or cylindrical, 10-40 mm, with 7-21 spirally aranged spikes; spikes 5-15 x 2.5-4 mm, turgid, obovoid to almost parallel-sided, with 10-25 glumes, glume-like bract c. 1 mm, acute, glume-like prophyll obtuse, bi-nerved, base corky, swollen; rachis 4-angled, c. 1 mm wide, c. 0.7 mm thick, compressed, internodes 1.2 mm, narrowly winged; glumes 2.2-2.8 mm, widely cymbiform, obtuse, sides dark reddish brown, sometimes greenish brown, margins scarious. Stamens 3; stigmas 2. Nut 1.4-1.6 x 1.2-1.3 mm, lenticular, widely obovoid or ellipsoid, brown, glossy, finely reticulate.
Fl. Per.: (April-) July - September.
Type: Italy, in surroundings of Bologna, c. 1760 F. Bassi C?.
In streams, irrigation channels, ditches, rice fields; Distribution: From S France and east C Europe to Vietnam, Taiwan and Japan; Turkey, Caucasus, Uzbekistan, Tadjikistan, Pakistan and NW India.
Kükenthal (1936) assigns Cyperus serotinus and his sect. Serotini to subg. Juncellus almost solely because of the distigmatic flowers. Typically, species of subg. Juncellus have pseudolateral, capitate inflorescences and thus C. serotinus with its compound inflorescence fits poorly into this group. It is therefore included here in subg. Cyperus (cf. Kükenthal l.c.: 40, 1935).
Immature specimen from Peshawar (Masih 30) is exceptional having very narrow, many-spiked distal cluster of spikes; variation of C. serotinus requires further study.