Agrostis gigantea, known by its common name black bent and redtop, is a perennial grass of the Agrostis genus.
The leaves are dull green. The ligule is blunt, but toothed and up to 6 millimetres (0.24 in) long.
The panicle is open and loose, of green or purplish colour. It flowers from June to August.
The leaves are rolled in shoot, not hairy, no auricles, but the plant has rhizomes.