white hellebore vs hellebore

white hellebore and hellebore both are nouns.

Word	Noun	Adjective	Verb	Adverb
white hellebore	Yes	No	No	No
hellebore	Yes	No	No	No

As nouns, hellebore is a hypernym of white hellebore; that is, hellebore is a word with a broader meaning than white hellebore:

white hellebore: North American plant having large leaves and yellowish green flowers growing in racemes; yields a toxic alkaloid used medicinally
hellebore: perennial herbs of the lily family having thick toxic rhizomes

Other hypernyms of white hellebore include false hellebore.

white hellebore (noun)	hellebore (noun)
North American plant having large leaves and yellowish green flowers growing in racemes; yields a toxic alkaloid used medicinally	any plant of the Eurasian genus Helleborus
	perennial herbs of the lily family having thick toxic rhizomes