Lolium L.
Type species: L. perenne L.
Annuals, or perennials, of variable habit. Leaf-sheath auriculate, or auricles 0. Ligule membranous, short, truncate or obtuse. Leaf-blade flat or ± folded, rolled or folded in young shoots. Culm ± decumbent to erect. Inflorescence a simple, stiff, terminal spike with mainly solitary spikelets alternating in two opposite rows and placed edgeways on and ± sunk in rachis. Spikelets 2-22-flowered, ± sessile, ± laterally compressed; disarticulation above glumes and between florets. Glumes both present and ± equal in terminal spikelet; lower absent in lateral spikelets, upper 3-7-nerved, coriaceous. Lemma 5-9-nerved, rounded, membranous to coriaceous; awn subterminal or 0. Palea ≈ lemma and similar in texture, 2-keeled, keels ciliolate. Callus glabrous. Lodicules 2, ± membranous, glabrous, ± lanceolate, entire. Stamens 3. Ovary glabrous; styles free. Caryopsis dorsiventrally compressed, longitudinally furrowed; embryo small; hilum linear, > ½ length of caryopsis.
Key
8 spp. of temperate Eurasia. Naturalised spp. 4; transient sp. 1.
Two spp., L. perenne, perennial ryegrass and L. multiflorum, Italian ryegrass, are extremely important pasture grasses in N.Z., as in many other temperate regions. Because of a long history of breeding within these two spp., and introgression between them, cultivated and naturalised plants frequently do not conform to the classical taxonomic descriptions of the species.
Annual and biennial cultivars of Italian ryegrass as well as the hybrid L. multiflorum × L. perenne cultivars, are valued for their superior winter growth, faster establishment, and high acceptability to livestock. Though much grown in pasture, L. multiflorum does not occur so commonly in the wild as L. perenne.
This account is based on the revision of Lolium by Terrell, E. E. Techn. Bull. U.S.D.A 1392: 1-65 (1968).
