black mallee vs mallee

black mallee and mallee both are nouns.

Word	Noun	Adjective	Verb	Adverb
black mallee	Yes	No	No	No
mallee	Yes	No	No	No

As nouns, mallee is a hypernym of black mallee; that is, mallee is a word with a broader meaning than black mallee:

black mallee: a small mallee with rough dark-colored bark toward the butt; yields a red eucalyptus kino gum
mallee: any of several low-growing Australian eucalypts

black mallee (noun)	mallee (noun)
a small mallee with rough dark-colored bark toward the butt; yields a red eucalyptus kino gum	any of several low-growing Australian eucalypts