Lolium perenne L.

Family: Poaceae, Tribe: Poeae

Pertinent Synonyms & Notes (particularly those used in California; go to GRIN for other synonyms)


Pertinent Common Names (particularly those used in California; go to GRIN for other common names)

perennial ryegrass

Primary Disseminule Type


Description (diagnostics are in brown)

Spikelets solitary, sessile, consisting of (2)5–10(15) fertile florets with similar-looking though diminished sterile florets at apex, oblong, laterally compressed, 5–22 mm long x 1–7 mm wide, disarticulating below each fertile floret.

Glumes usually 1, 2 in terminal spikelets, unawned. Lower glume absent from all but the terminal spikelet. Upper glume persistent, shorter, longer or equal to spikelet, similar to fertile lemma in texture, narrowly lanceolate, 3.5–15 mm long, coriaceous, without keel, 5–7-veined, surface smooth, glabrous, apex obtuse.

Fertile florets: rachilla persistent, glabrous to pubescent, <0.25 length of lemma when empty (no sterile floret attached), callus very short, blunt, glabrous.

Lemma oblong to lanceolate, 3.5–9 mm long x 0.8–2 mm wide, coriaceous, without keel, 5-veined, surface smooth below, scaberulous near margins and hyaline apex, apex obtuse to acute, awnless or awn to 3(8) mm long, attached 0.2–0.7 mm below apex.

Palea shorter to slightly longer than lemma, keels scaberulous.

Caryopsis elliptic or oblong to oblanceolate, 2–5.5 mm long x 0.7–1.5 mm wide, typically 3+ times longer than wide, brown, hilum linear.

Similar Species

Similar Species Comparison Chart

Risk Assessment (codes in yellow or red indicate cause for concern; assessments are current as of mid-2011; click AUQP, NZBORIC, or NZBPI for access to the most recent versions of these databases and possible assessment changes)