family Gramineae vs gramineous plant

family Gramineae and gramineous plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
family Gramineae	Yes	No	No	No
gramineous plant	Yes	No	No	No

family Gramineae (noun)	gramineous plant (noun)
the grasses: chiefly herbaceous but some woody plants including cereals, bamboo, reeds, sugar cane	cosmopolitan herbaceous or woody plants with hollow jointed stems and long narrow leaves