bitter cress vs bittercress

bitter cress and bittercress both are nouns.

Word	Noun	Adjective	Verb	Adverb
bitter cress	Yes	No	No	No
bittercress	Yes	No	No	No

As nouns, bitter cress and bittercress are synonyms defined as:

bitter cress and bittercress: any of various herbs of the genus Cardamine, having usually pinnate leaves and racemes of white, pink or purple flowers; cosmopolitan except Antarctic

bitter cress (noun)	bittercress (noun)
any of various herbs of the genus Cardamine, having usually pinnate leaves and racemes of white, pink or purple flowers; cosmopolitan except Antarctic	any of various herbs of the genus Cardamine, having usually pinnate leaves and racemes of white, pink or purple flowers; cosmopolitan except Antarctic