Knotgrass or knot grass is the common name for several plants and a moth and may refer to: *''

Paspalum distichum ''Paspalum distichum'' is a species of Poaceae, grass. Common names include knotgrass, water finger-grass, couch paspalum, eternity grass, gingergrass, and Thompson grass. Its native range is obscure because it has long been present on most conti ...

'', a species of grass *'' Polygonum'', a genus of plants in the buckwheat family, more often known as knot weed *'' Acronicta rumicis'', a moth of the family Noctuidae

See also