Lolium temulentum L.

Family: Poaceae, Tribe: Poeae

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

Lolium arvense With.

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

poison ryegrass

Primary Disseminule Type


Description (diagnostics are in brown)

Spikelets solitary, sessile, consisting of 2–10 fertile florets with similar-looking though diminished sterile florets at apex, oblong, laterally compressed, 5–30 mm long x 1–8 mm wide, disarticulating below each fertile floret at maturity.

Glumes usually 1, 2 in terminal spikelets, unawned. Lower glume absent from all but the terminal spikelet. Upper glume persistent, reaching or exceeding apex of florets, similar to fertile lemma in texture, lanceolate, 5–30 mm long (shorter or longer than spikelet), coriaceous, without keels, 7–9-veined, surface smooth or asperulous, apex obtuse.

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

Lemma broadly elliptic to ovate, 3.5–8.5 mm long x 1.2–3 mm wide, coriaceous, without keel, 5–9-veined, swollen at maturity (lower lemmas only), surface smooth below, scabrid near hyaline apex, apex obtuse or bifid, awnless or awn to 23 mm long, attached 0.2–2 mm below apex.

Palea shorter to slightly longer than lemma, keels scaberulous.

Caryopsis oblong, 3.2–7 mm long x 1–3 mm wide, 2–3 times longer than wide, turgid, 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)