Elymus repens, commonly known as couch grass, is a very common perennial species of grass native to most of Europe, Asia, and northwest Africa. Other names include twitch, quick grass, quitch grass (also just quitch), dog grass, quackgrass, scutch grass, and witchgrass.

It has creeping rhizomes which enable it to grow rapidly across grassland. The stems ('culms') grow to 40–150 cm tall; the leaves are linear, 15–40 cm long and 3–10 mm broad at the base of the plant, with leaves higher on the stems 2–8.5 mm broad. The flower spike is 10–30 cm long, with spikelets 1–2 cm long, 5–7 mm broad and 3 mm thick with three to eight florets. The glumes are 7–12 mm long, usually without an awn or with only a short one.

It flowers at the end of June through to August in the northern hemisphere.

blunt ligule 1mm high, also showing a few very fine hairs of the plant

showing the leaf is dull green, mainly parallel, with auricles and ribbed

rhizomes

showing general tufted and visual appearance of the plant

.

Various taxonomic subdivisions of this species have been proposed. Moreover, it is assigned to various genera (Elymus, Elytrigium, Agropyron). In a recent classification, three subspecies are distinguished, one of these with an additional variety: