Perennial, 80-100 cm. Rhizome strong, with short stolons. Stem 2-3 mm diam., sharply trigonous, smooth. Leaves shorter than stem; sheaths to 20-30 cm, brown or reddish-brown,lowest bladeless, upper yellowish or with reddish tint, mouth margin straight; blades to c. 50 cm, 7 mm wide, flat or keeled, grey-green, margins and midnerve below scabrous, margins slightly revolute, apex acute, trigonous, scabrous. Inflorescence up to c. 30 cm long, rather narrow anthelodium, primary branches 5-15, up to c.20 cm, longest often with secondary anthelodia up to 10 cm, with scarious, brown, tubular prophyll; lowest 3-4 bracts foliose, to more than 50 cm; cluster of spikes by 3-15 spikes almost digitately arranged, 10-20 mm in diam., tight. Spikes 5-15 x c. 1.5 mm, with 10-15 flowers, glume-like bract c. 1.5 mm, glume-like prophyll c. 1.5 mm, two-nerved; rachis compressed, quadrangular, slightly zigzagging, not winged; glumes c. 3 mm, cymbiform, blunt, mid-vein green, sides brown or reddish brown, margins scarious. Anthers c. 1.5 mm. Nut c. 1 x 0.5 mm, obovoid, trigonous, grey-brown, finely reticulate.

Fl. Per.: June -October.

Type: "Habitat in Italiae, Galliae paludibus.".

On wet meadows, marshlands, ricefields; Distribution: C and S Europe, N, E and W Africa, in east as far as eastern Kazakhstan, Pakistan and N.W. India.

C. longus in Pakistan, at eastern limits of its area, is less robust than in Flora Iranica area; its base is thinner, internodes of rhizome are long, and stolons are longer and thinner. It is reminiscent of tall plants of C. rotundus.