wolfbane vs wolf's bane

wolfbane and wolf's bane both are nouns.

Word	Noun	Adjective	Verb	Adverb
wolfbane	Yes	No	No	No
wolf's bane	Yes	No	No	No

As nouns, wolfbane and wolf's bane are synonyms defined as:

wolfbane and wolf's bane: poisonous Eurasian perennial herb with broad rounded leaves and yellow flowers and fibrous rootstock

Other synonyms of wolfbane include Aconitum lycoctonum, wolfsbane.

wolfbane (noun)	wolf's bane (noun)
poisonous Eurasian perennial herb with broad rounded leaves and yellow flowers and fibrous rootstock	poisonous Eurasian perennial herb with broad rounded leaves and yellow flowers and fibrous rootstock