7. Cyperus corymbosus Rottb., Descr. Pl. Rar. 19. 1772; C.B.Clarke in Hook.f., Fl. Brit.Ind. 6: 612. 1893; R.R.Stewart, l.c. 93; Kukkonen in Rech.f., l.c. 95.
Cyperus diphyllus Retz., Observ. bot. 5: 11. 1789; C. koenigii Vahl, Enum. Pl. 2: 302. 1805; Rottb., Descr. & Icon. Pl. Rar., t.VII, fig.4. 1773. Haines & Lye, Sedges and Rushes E. Afr.: Fig. 354. 1983.
Perennial, 80-120 cm. Rhizome horizontal, 4-5 mm diam., woody. Stem 3-5 mm diam., trigonous above, smooth. Leaves reduced; sheaths to 30 cm, greyish green or brownish, often with reddish tint, mouth margin oblique; blades occasionally to 80 mm, 4 mm wide, rigid, smooth or slightly scabrous. Inflorescence a conical compound anthelodium, 10-20 cm; bracts 3-5 foliose, shorter than inflorescence, up to 16 cm and up to 6 mm wide, flat or margins slightly recurved, margins and keel scabrous, apex smooth or slightly scabrous, rather obtuse; primary branches 5-12, up to 130 mm; tubular prophyll up to 20 mm; secondary anthelodia to 80 mm, bracts up to 12 mm, c. as long as secondary tubular prophyll, secondary branches up to 45 mm, tertiary anthelodia occasional, tertiary branches 1-3, to 15 mm; cluster of spikes up to 20 x 30 mm, with 5-15 spikes, spikes reflexed; spikes 5-25 x c. 1 mm, with 8-22 glumes, fusiform, terete, glume-like bract c. 1.5 mm, glume-like prophyll c. 1.5 mm, with spongy basis; rachis quadrangular, c. 0.2 mm wide, internodes c. 0.8 mm, winged; glumes 2-2.5 mm, loosely imbricating, cymbiform, straw coloured to reddish brown, mid-nerve not pronounced, mucronate, apex rounded, margins widely scarious. Anthers c. 1 mm. Nuts not seen.
Fl. Per.: June.
Type: India: C-König, microf. 4: 17-18!, conf. Kük., l.c.: 80, 1935.
Flooded river banks; Distribution: Pakistan; in tropical and subtropical regions from Myanmar and Sri Lanka west to Africa and the Americas.
The above description is based on Iraqi material and specimens from India, primarily on: Khasia, 17. 11. 1850 Hooker & Thomson (K) and Andhra Pradesh, Samalkot Distr., Godawari, Madras hrb. no. 12494 (K).
The name C. corymbosus Rottb. in solely to be assigned to Rottboell. The protologue (Rottb. 1772) cites as a synonym Scirpus corymbosus L., which is Rhynchospora corymbosa (L.) Britton, however, with a question mark, and later Rottboel (l.c., 1773) definitely excludes the synonym (see Kukkonen, Ann. Bot. Fennici 35: 169-170, 1998).