verbena vs vervain

verbena and vervain both are nouns.

Word	Noun	Adjective	Verb	Adverb
verbena	Yes	No	No	No
vervain	Yes	No	No	No

As nouns, verbena and vervain are synonyms defined as:

verbena and vervain: any of numerous tropical or subtropical American plants of the genus Verbena grown for their showy spikes of variously colored flowers

verbena (noun)	vervain (noun)
any of numerous tropical or subtropical American plants of the genus Verbena grown for their showy spikes of variously colored flowers	any of numerous tropical or subtropical American plants of the genus Verbena grown for their showy spikes of variously colored flowers