This species was originally included within the genus
Festuca, owing to the similarity of the flowers and inflorescences. However, there has been much debate since 1898 about its relationship to the genus
Lolium, largely because of hybridization with
Lolium perenne (species in separate genera are far less likely to form hybrids than those within the same genus). Recent DNA studies have shown that it should indeed be considered a ryegrass (
Lolium) rather than a fescue (
Festuca) because these species are more closely related to each other, despite the fact that ryegrasses have inflorescences of spikes rather than racemes. Its chromosome number is 2n = 14. It hybridises with
Lolium perenne to produce the cross now called
Lolium ×
elongatum (Ehrh.) Banfi, Galasso, Foggi, Kopecký & Ardenghi (formerly x
Festulolium loliaceum) and with
Lolium multiflorum to produce
Lolium ×
subnutans (Holmb.) Banfi, Galasso, Foggi, Kopecký & Ardenghi (formerly x
Festulolium braunii). ==Habitat and ecology==