Lolium perenne Linn., Sp. Pl. 1:83. 1753. Boiss., Fl. Or. 5:679. 1884; Duthie, Fodder Grasses 68. 1888; Hook.f., Fl. Brit. Ind. 7:365. 1896; Bor, Fl. Assam 5:65. 1940; Sultan & Stewart, Grasses W. Pak. 2:205. 1959; Bor, Grasses Burma Ceyl. Ind. Pak. 545. 1960; Bor in Towns., Guest & Al-Rawi, Fl. Iraq 9:93. 1968; Bor in Rech. f., Fl. Iran. 70:93. 1970; Tzvelev, Poaceae URSS 420. 1976; Humphries in Tutin et al., Fl. Eur. 5:154. 1980.
Loosely to densely tufted perennial; culms 10-90 cm high, erect or spreading, sometimes prostrate and rooting from the lower nodes, slender. Leaf-blades 5-14(-30) cm long, 2-4(-6) mm wide, folded when young, with or without auricles up to 3 mm long at the base. Spikes straight or slightly curved, 3-30 cm long, stiff, slender to moderately stout, the spikelets usually less than their own length apart but sometimes more widely spaced. Spikelets 5-20 mm long, 3-10 (-14)-flowered; upper glume 3.5-15 mm long, one-third to as long as the spikelet, rarely exceeding it, 3-9-nerved, acute or obtuse; lemmas oblong or oblong-lanceolate, 3.5-9 mm long, smooth, obtuse or subacute, not turgid at maturity, usually awnless but rarely with an awn up to 8 mm long.
Fl. & Fr. Per.: May-July.
Type: Europe, Linnaeus (LINN ).
Distribution: Pakistan (Baluchistan, Punjab, N.W.F.P & Kashmir); Widespread in Europe, temperate Asia and North Africa; widely introduced elsewhere.
Perennial Rye-Grass freely hybridizes with other species of Lolium and occasionally with species of Festuca. It is extremely variable, especially in the structure of the inflorescence which may be loosely branched or shortened and much congested. It is extensively cultivated as a lawn, forage or soil-binding grass.