mountain clematis vs purple clematis

mountain clematis and purple clematis both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain clematis	Yes	No	No	No
purple clematis	Yes	No	No	No

As nouns, mountain clematis and purple clematis are synonyms defined as:

mountain clematis and purple clematis: climber of northeastern North America having waxy purplish-blue flowers

Other synonyms of mountain clematis include Clematis verticillaris, purple virgin's bower.

mountain clematis (noun)	purple clematis (noun)
climber of northeastern North America having waxy purplish-blue flowers	climber of northeastern North America having waxy purplish-blue flowers