Synonyms: Avena elatius
Other names: Bulbous Oatgrass, False Oats, False Oatgrass, Onion Couch, Onion Twitch, Onion-rooted Twitch, Tall Oat-grass, Tall Oatgrass
Arrhenatherum elatius, with the common names false oat-grass, tall oat-grass, tall meadow oat, onion couch and tuber oat-grass, is a perennial species of grass, common in the temperate regions of Europe.
This bunchgrass is often used as an ornamental grass.
It is native to Europe but can be found elsewhere as an introduced species. It is found especially in prairies, at the side of roads and in uncultivated fields. The bulbous variety can be a weed of arable land. It is palatable grass for livestock and is used both as forage (pasture) and fodder (hay and silage); it has high amounts of phosphorus and calcium in its tissues.
This course grass can grow to 150cm tall. The leaves are bright green, broad, slightly hairy and rough. The ligule is 3mm long and smooth edged. The panicle is up to 30cm, and the bunched spikelet have projecting and angled awns up to 17mm long, green or purplish. The panicles often remain into winter. The spikelets are oblong or gaping. It flowers from June to September. The roots are yellow. 
Images: Forest Starr & Kim Starr, CC-BY Creative Commons Attribution License 3.0