wolfsbane vs wolf's bane

wolfsbane and wolf's bane both are nouns.

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

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

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

Other synonyms of wolfsbane include Aconitum lycoctonum, wolfbane.

wolfsbane (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