plume grass vs genus Erianthus

plume grass and genus Erianthus both are nouns.

Word	Noun	Adjective	Verb	Adverb
plume grass	Yes	No	No	No
genus Erianthus	Yes	No	No	No

plume grass (noun)	genus Erianthus (noun)
a reedlike grass of the genus Erianthus having large plumes	genus of reedlike grasses having spikes crowded in a panicle covered with long silky hairs