family Gramineae vs genus Festuca

family Gramineae and genus Festuca both are nouns.

Word	Noun	Adjective	Verb	Adverb
family Gramineae	Yes	No	No	No
genus Festuca	Yes	No	No	No

family Gramineae (noun)	genus Festuca (noun)
the grasses: chiefly herbaceous but some woody plants including cereals, bamboo, reeds, sugar cane	a genus of tufted perennial grasses of the family Gramineae