Italian Ryegrass (Lolium multiflorum) is a biennial spiked grass native to temperate Europe which is used for silage and as a cover crop. Often used over winter to help prevent soil erosion, build soil structure and help suppress weeds. It often has red/purple leaf sheaths at ground level and has wide, glossy leaves. Visually, IRG is very similar to Perennial Ryegrass (Lolium perenne) but the latter has narrower leaves and the former has small awns on the spikelets whereas PRG lacks this attribute.
IRG can also be mistaken for Couch Grass but the main difference here is that the spikelets of couch grass join the stem broad side on. IRG spikelets join the stem on their narrow side.
Diploid Ryegrasses have two chromosomes per cell, as opposed to tetraploid Ryegrasses which have four. In basic terms, this means diploids combine yield and robustness, so they are capable of delivering in less than ideal conditions. Being fast to establish, they are very competitive with weeds and can cope with lower fertility and wetter environments than tetraploids.