quackgrass vs Agropyron repens

quackgrass and Agropyron repens both are nouns.

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

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

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

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

quackgrass (noun)	Agropyron repens (noun)
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