Arrhenatherum

Arrhenatherum is a small genus of grasses in the family Poaceae, commonly known as oatgrasses. The genus comprises a few perennial species, of which Arrhenatherum elatius, the tall oatgrass or false oatgrass, is the most widely distributed.

They are rhizomatous perennials that form dense tussocks. Leaves are narrow and flat with a moderate-length ligule. The flowering stems bear open panicles of spikelets, typically two to four florets per spikelet, and plants may reach substantial height depending on species and conditions.

Arrhenatherum elatius is native to Europe, western Asia, and parts of North Africa. The genus also includes other smaller species. In many regions outside its native range, tall oatgrass has been introduced as a forage or ornamental plant and has become naturalized in disturbed or moist habitats, occasionally forming dense stands that crowd out natives.

Tall oatgrass is valued for forage, hay, and turf applications and tolerates cool, temperate climates with fertile soils. In some non-native settings it can form dense stands that reduce biodiversity and alter plant communities. It is often managed by mowing, grazing, or selective removal, and restoration efforts may reseed native grasses.

Arrhenatherum is placed in the Poaceae family, tribe Poeae, subtribe Loliinae. Relationships with Avena have varied; some classifications treated Arrhenatherum as part of Avena, while others recognize Arrhenatherum as a distinct genus.