Cymbopogon Spreng., Pl. Pugill. 2:14. 1815. Blatter & McCann, Bombay Grasses 100. 1935; Bor, El. Assam 5:382. 1940; Bor in J. Bombay nat. Hist. Soc. 51: 890. 1953; Sultan & Stewart, Grasses W. Pak. 1:110. 1958; Bor, Grasses Burma Ceyl. Ind. Pak. 121. 1960; Bor in Towns., Guest & Al-Rawi, Fl. Iraq 9:514. 1968; Bor in Rech. f., Fl. Iran. 70:541. 1970; Tzvelev. Poaceae URSS 716. 1976; Soenarko in Reinwardtia 9: 225-375. 1977.
Tall robust perennials. Leaf-blades linear, aromatic; ligule membranous or scarious. Inflorescence composed of paired racemes borne on a short common peduncle and ± enclosed by a boat-shaped spatheole, these densely crowded into a leafy false panicle which is often very large and complex; racemes short, each borne upon a very short flattened raceme-base which is deflexed at maturity, the lowermost pair of spikelets in each raceme homogamous and resembling the pedicelled; internodes and pedicels linear. Sessile spikelet ± dorsally compressed; callus obtuse, inserted in the concave or cupular tip of the internode; lower glume ± chartaceous, often streaked with oil glands, shallowly concave or with a V-shaped median groove (occasionally deeply concave or slightly convex), 2-keeled, the keels usually lateral and often winged near the apex, with or without inter-carinal nerves; lower floret reduced to a hyaline lemma; upper lemma hyaline or stipitiform, bilobed (very rarely entire), with or without a glabrous awn from the sinus; palea absent; caryopsis oblong, subterete to planoconvex. Pedicelled spikelet male or barren, ± as long as the sessile but never depressed on the back, awnless.
A genus of about 40 species in the Old World tropics and subtropics, elsewhere introduced or in cultivation only; 6 species occur in Pakistan.
Cymbopogon is closely allied to Andropogon and Hyparrhenia, and is sometimes quite difficult to separate from them (Clayton in Kew Bull. 19:454. 1965). A useful diagnostic character is the aromatic flavour when a leaf of Cymbopogon is chewed: the other genera are tasteless. Five species are commercially cultivated in various parts of the World for their oils (Lemon-grass oil, Citronella oil. etc.). In Southeast Asia Cymbopogon citratus (DC.) Stapf is widely used for culinary purposes. Because of their unpleasant taste, mature Cymbopogon plants are rarely grazed. The plants are more palatable when young and some species are very important for grazing since they grow quickly after the rains. Cymbopogon jwarancusa is an important element in the fixation and reclamation of sand-dunes.
The genus is notorious for the considerable variation within species and the weak separation between them. Consequently its taxonomy is still in a fluid state, with differing opinions about the level at which specific rank should be accorded, and with many of the proposed species based upon indefinite characters of little practical diagnostic value. There is also a pronounced tendency towards disjunct or vicarious distributions, but these may be no more than artefacts of a faulty taxonomy.
Cymbopogon gidarba (Ham ex Steud.) Haines is erroneously recorded from Pakistan (Stewart in Ann. Cat. Vase. Pl. Pak. 107), being restricted to the eastern Himalayas, Bihar, Orissa and Madras State.