Bromus secalinus vs brome

Bromus secalinus and brome both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bromus secalinus	Yes	No	No	No
brome	Yes	No	No	No

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

Bromus secalinus: weedy annual native to Europe but widely distributed as a weed especially in wheat
brome: any of various woodland and meadow grasses of the genus Bromus; native to temperate regions

Other hypernyms of Bromus secalinus include bromegrass.

Bromus secalinus (noun)	brome (noun)
weedy annual native to Europe but widely distributed as a weed especially in wheat	any of various woodland and meadow grasses of the genus Bromus; native to temperate regions