witchgrass vs Agropyron repens

witchgrass and Agropyron repens both are nouns.

Word	Noun	Adjective	Verb	Adverb
witchgrass	Yes	No	No	No
Agropyron repens	Yes	No	No	No

As nouns, witchgrass and Agropyron repens are synonyms defined as:

witchgrass and Agropyron repens: European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed

Other synonyms of witchgrass include couch grass, dog grass, quack grass, quackgrass, quick grass, witch grass.

witchgrass (noun)	Agropyron repens (noun)
North American grass with slender brushy panicles; often a weed on cultivated land	European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed
European grass spreading rapidly by creeping rhizomes; naturalized in North America as a weed