It exhibits no tillers, either rhizomes or stolons. Perennial Ryegrass grows as a bunchgrass, that is a large multitude of stems originate from the crown of the plant, however, no branching occurs above ground level. The auricles of Perennial Ryegrass are short and not clasping at the stem. The sheath is split and overlapping with a reddish base.
Ligules are short, truncate, unfringed membranes with teeth near the tip.
The bottom is glassy and smooth with a prominent midrib. The edges taper to a tip. The inflorescence is compact, as a single stalk with hollow rachides. Spikelets are attached and set on edge to the main stem. They are solitary, sessile, and flattened.