quack grass vs Agropyron repens

quack grass and Agropyron repens both are nouns.

Word	Noun	Adjective	Verb	Adverb
quack grass	Yes	No	No	No
Agropyron repens	Yes	No	No	No

As nouns, quack grass and Agropyron repens are synonyms defined as:

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

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

quack grass (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