[4][5][6][7] Alopecurus geniculatus is a perennial grass forming bunches of erect stems up to about 60 cm (24 inches) in height.

The pale green to purplish inflorescence is a dense panicle up to 6 or 7 cm long which blooms in dusty yellow-orange anthers.

[11] Alopecurus geniculatus is a component of purple moor grass and rush pastures a type of Biodiversity Action Plan habitat in the UK.

It occurs on poorly drained neutral and acidic soils of the lowlands and upland fringe.

The grass has spread significantly in the United States since it was first introduced.