genus Dioscorea vs plant genus

genus Dioscorea and plant genus both are nouns.

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

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

genus Dioscorea (noun)	plant genus (noun)
the genus of yams (Dioscorea)	a genus of plants