genus Pinckneya vs bitter-bark

genus Pinckneya and bitter-bark both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Pinckneya	Yes	No	No	No
bitter-bark	Yes	No	No	No

genus Pinckneya (noun)	bitter-bark (noun)
small genus of shrubs or small trees of southeastern United States and northern South America	ornamental shrub or small tree of swampy areas in southwestern United States having large pink or white sepals and yielding Georgia bark for treating fever