Common Name: Ryegrasses
Description: Tufted annuals or perennials.
Leaves with ligule membranous; blade flat.
Inflorescence a terminal spike of erect spikelets.
Spikelets solitary, sessile, laterally flattened, arranged alternately with one edge appressed to the axis, and partly in concavities of the rachis; bisexual with 3–20 florets; rachilla disarticulating above the glumes and between the lemmas. Lower glume absent on all but the terminal spikelet; upper glume strongly 3–9-nerved, flat or slightly concave; terminal spikelet with 2 equal glumes. Lemmas rounded on the back, 5–9-nerved, firm, with translucent tip, obtuse, acute or awned with a straight, subapical awn. Palea subequal to the lemma, 2-keeled.
Distribution and occurrence: World: c. 10 species, Europe, Mediterranean region, temperate regions of Asia. Australia: 5 species (naturalized), all States.
Perennial Ryegrass was probably the first grass deliberately sown for pastures and, with the Italian Ryegrass, is one of the most widely grown pasture grasses of temperate countries. Annual Ryegrasses are often crop weeds. Identification is difficult because many species hybridize freely, for example L. perenne, L. multiflorum and L. rigidum, the hybrid populations showing a continuum of variation. Lolium is also closely related to broad-leaved species of Festuca, such as F. pratensis, and L. perenne and L. multiflorum will hybridize with the former to give X Festulolium. Key adapted from Wheeler et. al. (1990).
Text by S. W. L. Jacobs & K. L. McClay
Taxon concept:
| | Key to the species | |
| 1 | Plants annual, will pull up easily when mature | 2 |
| Plants perennial; cannot be pulled up easily when mature and forming a large tuft | 6 |
| 2 | Lemmas swollen at maturity, ovate to elliptic, usually with an awn 0.7–2 cm long; glume equal to or exceeding the spikelets | Lolium temulentum |
| Lemmas not swollen at maturity, lanceolate, awned or awnless; glume length variable
Back to 1 | 3 |
| 3 | Lemmas with awns more than 3 mm long; spikelets rarely with less than 10 florets | Lolium multiflorum & hybrids |
| Lemmas awnless or with an awn less then 3 mm long; spikelets with 3–22 florets
Back to 2 | 4 |
| 4 | Glume distinctly shorter than spikelet; young leaves folded in bud, leaves narrow, usually less than 4 mm wide | Lolium perenne |
| Glume almost as long as, or exceeding, the spikelet; leaves rolled in the bud, usually more than 3 mm wide
Back to 3 | 5 |
| 5 | Rachis rigid and stout, c. 2 mm diam., often oval in cross section; spikelets narrow, often embedded in the rachis; plant usually less than 35 cm high | Lolium loliaceum |
| Rachis thin, c. 1 mm diam. and usually round in cross section; spikelets not as narrow, more or less embedded in rachis; plant usually more than 35 cm high
Back to 4 | Lolium rigidum |
| 6 | Lemmas with an awn longer than 3 mm long; about 20 florets per spikelet; leaves rolled in the bud | Lolium multiflorum |
| Lemmas awnless or with an awn less than 3 mm long; spikelets with about 10 florets; leaves folded in the bud
Back to 1 | Lolium perenne |
|
