genus Mertensia vs plant genus

genus Mertensia and plant genus both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Mertensia	Yes	No	No	No
plant genus	Yes	No	No	No

As nouns, plant genus is a hypernym of genus Mertensia; that is, plant genus is a word with a broader meaning than genus Mertensia:

genus Mertensia: a genus of herbs belonging to the family Boraginaceae that grow in temperate regions and have blue or purple flowers shaped like funnels
plant genus: a genus of plants

genus Mertensia (noun)	plant genus (noun)
a genus of herbs belonging to the family Boraginaceae that grow in temperate regions and have blue or purple flowers shaped like funnels	a genus of plants