downy brome vs brome

downy brome and brome both are nouns.

Word	Noun	Adjective	Verb	Adverb
downy brome	Yes	No	No	No
brome	Yes	No	No	No

As nouns, brome is a hypernym of downy brome; that is, brome is a word with a broader meaning than downy brome:

downy brome: annual or winter annual grass with softly hairy leaves of the Mediterranean
brome: any of various woodland and meadow grasses of the genus Bromus; native to temperate regions

Other hypernyms of downy brome include bromegrass.

downy brome (noun)	brome (noun)
annual or winter annual grass with softly hairy leaves of the Mediterranean	any of various woodland and meadow grasses of the genus Bromus; native to temperate regions