couch grass vs quackgrass

couch grass and quackgrass both are nouns.

Word	Noun	Adjective	Verb	Adverb
couch grass	Yes	No	No	No
quackgrass	Yes	No	No	No

As nouns, couch grass and quackgrass are synonyms defined as:

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

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

couch grass (noun)	quackgrass (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