panicum repens is a species of grass known by many common names, including torpedograss, creeping panic, panic rampant, couch panicum, wainaku grass, quack grass, dog-tooth grass, and bullet grass. its exact native range is obscure. sources suggest that the grass is native to "africa and/or asia", "europe or australia", "eurasia", "australia", "europe, asia, and africa", or other specific regions, including the mediterranean, israel, and argentina. it is present in many places as an introduced species and often a noxious weed. it has been called "one of the world's worst weeds."