Heuchera americana vs alumbloom

Heuchera americana and alumbloom both are nouns.

Word	Noun	Adjective	Verb	Adverb
Heuchera americana	Yes	No	No	No
alumbloom	Yes	No	No	No

As nouns, alumbloom is a hypernym of Heuchera americana; that is, alumbloom is a word with a broader meaning than Heuchera americana:

Heuchera americana: plant with basal leaves mottled with white and flowers in lax panicles on erect stems
alumbloom: any of several herbs of the genus Heuchera

Other hypernyms of Heuchera americana include alumroot.

Heuchera americana (noun)	alumbloom (noun)
plant with basal leaves mottled with white and flowers in lax panicles on erect stems	any of several herbs of the genus Heuchera