Citation: L., Sp. Pl. 83 (1753).

Derivation: Latin name for L. temulentum.

Synonymy: Not Applicable

Common name: Ryegrasses.

Description:
Glabrous annual or perennial herbs; leaf blade flat; ligule membranous, very short, truncate.

Inflorescence usually a spike; spikelets sessile and distichous in the alternate notches of the cylindrical continuous (non-articulate) rhachis of the spike and appressed to it by one of their sides (back of the glumes and the lemmas), 3-25-flowered including 0-2 rudimentary florets; glume 1 except in the terminal spikelet which has 2 glumes, stiff, convex, several-nerved; lemmas 5-nerved, rounded on the back.

Distribution:  8 species from temperate parts of Europe and Asia, well established in southern Australia.

Biology: No text

Uses: Important perennial and annual pasture grasses; in crops, the annual species are the most serious grassy weeds. (Kloot (1983)Aust. J. Bot. 31:421-435.)

Key to Species:

1. Lemmas with an awn longer than 5 mm
2. Rhachis thin or stout (to c. 2 mm diam.); florets swollen at maturity, approximately 3 times as long as broad (very rare)
3. Large spikelets containing more than 6 florets; stout rhachis (c. 2 mm diam.); outer glume as long as or longer than the spikelet	L. temulentum forma temulentum 9a.
3. Small spikelets containing about 4 or 5 florets; thin rhachis (c. 1 mm diam.); outer glume always exceeding the spikelet	L. remotum 7.
2. Rhachis always thin (c. 1 mm diam.); florets not swollen or only slightly so, more than 3 times as long as broad
4. Outer glume one-quarter to one-half the length of the spikelet	L. multiflorum 3.
4. Outer glume one-half to equal length of the spikelet	L. multiflorum x rigidum 4.
1. Lemmas awnless or (usually the uppermost) with an awn much shorter than 5 mm
5. Florets swollen at maturity, approximately 3 times as long as broad (very rare)	L. temulentum forma arvense 9b.
5. Florets not swollen at maturity, at least 5 times as long as broad
6. Outer glume between one-quarter and one-half the length of the spikelet; awn absent or of variable length; often with branched rhachis	L. xhybridum 1.
6. Outer glumes at least one-half the length of the spikelet; awns generally absent; rhachis never branched
7. Outer glume about one-half to three-quarters the length of the spikelet; if glume longer then spikelets very small (c. 5 mm long) and borne at the end of long thin culms
8. Plants green to straw-coloured	L. perenne 5.
8. Plants reddish, particularly at the nodes	L. perenne x L. rigidum 6.
7. Outer glume slightly shorter to slightly longer than the spikelet; spikelet never very small nor borne at the end of long thin culms
9. Stems rarely reddish but if so, then the nodes not conspicuously darker; rhachis very stout, c. 2 mm diam.; culms to 30 cm; in mature plants the rhachis longer than the remainder of the culm; spikelets never exceeding the glume	L. loliaceum 2.
9. Stems reddish, particularly at the nodes which are generally darker than the stems; rhachis flexuose, c. 1 mm diam.; if stouter then culms at least 70 cm high; in mature plants the rhachis always (much) shorter than the remainder of the culm; spikelets generally exceeding the glume	L. rigidum 8.

Author: Prepared by P.M. Kloot