False oat-grass (Tall oat-grass, Tall meadow oat, Onion couch, Tuber oat-grass)
Arrhenatherum elatius

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.[citation needed]

Two subspecies have been described:
Arrhenatherum elatius subsp. elatius, the more common variety.
Arrhenatherum elatius var. bulbosum (also called Arrhenatherum tuberosum), onion couch or tuber oat-grass, distinguished by the presence of corms at the base of the stem, by which it propagates. Occurs in vegetated shingle and arable land.