The Germans call all poisonous herbs “banes,” and the Greeks, mistaking the word for “beans,” translated it by kuamoî, as they did “hen-bane” (huos kuamos). Wolf's-bane is an aconite with a pale yellow flower, called therefore the white -bane to distinguish it from the blue aconite. White-bean would be in Greek leukos kuamos, which was corrupted into lukos kuamos (wolf-bean); but botanists, seeing the absurdity of calling aconite a “bean,” restored the original German word “bane,” but retained the corrupt word lukos (wolf), and hence the ridiculous term “wolf's-bane.” (H. Fox Talbot.)
This cannot be correct: (1) bane is not German; (2) huos kuamos would be hog-bean, not hen-bane; (3)
How could Greeks mistranslate German? The truth is, wolf-bane is so called because meat saturated with its juice was supposed to be a wolf-poison.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894