witchgrass

(noun) North American grass with slender brushy panicles; often a weed on cultivated land. Synonyms: witch grass, old witchgrass, old witch grass, tumble grass, Panicum capillare.

(noun) European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed. Synonyms: dog grass, couch grass, quackgrass, quack grass, quick grass, witch grass, Agropyron repens.