Plants annual. Culms to 120 cm. Blades to 27 cm long, 1–12 mm wide. Spikes 2–40 cm, with 3–26 spikelets; rachises 0.5–3.5 mm thick at the nodes, spikelets not sunken in the rachises, not concealed by the glumes. Spikelets 5–28 mm long, 1–8 mm wide, with 2–10 florets. Glumes 5–28 mm, membranous to indurate; lemmas 3.5–8.5 mm long, 1.2–3 mm wide, unawned or awned, awns to 23 mm, attached 0.2–2 mm below the apices; paleas 1.2 mm shorter than to 0.8 mm longer than the lemmas, often wrinkled; anthers1.5–4 mm. Caryopses 3.2–7 mm long, 1–3 mm wide, 2–3 times longer than wide, turgid. 2n = 14.

Lolium temulentum is said to be the tares of the Bible. Its two subspecies differ mainly in quantitative characters.