rockcress vs rock cress

rockcress and rock cress both are nouns.

Word	Noun	Adjective	Verb	Adverb
rockcress	Yes	No	No	No
rock cress	Yes	No	No	No

As nouns, rockcress and rock cress are synonyms defined as:

rockcress and rock cress: any of several rock-loving cresses of the genus Arabis

rockcress (noun)	rock cress (noun)
any of several rock-loving cresses of the genus Arabis	any of several rock-loving cresses of the genus Arabis
noxious cress with yellow flowers; sometimes placed in genus Sisymbrium