genus Penstemon vs Penstemon

genus Penstemon and Penstemon both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Penstemon	Yes	No	No	No
Penstemon	Yes	No	No	No

As nouns, genus Penstemon and Penstemon are synonyms defined as:

genus Penstemon and Penstemon: large genus of subshrubs or herbs having showy blue or purple or red or yellow or white flowers; mostly western North America

genus Penstemon (noun)	Penstemon (noun)
large genus of subshrubs or herbs having showy blue or purple or red or yellow or white flowers; mostly western North America	large genus of subshrubs or herbs having showy blue or purple or red or yellow or white flowers; mostly western North America