may become a wolf when the Wolfsbane blooms and the autumn moon is bright"
The Wolfman, 1941
I did a little digging and found that this beautiful plant, also called Lamarck’s Wolfsbane, Northern Wolfsbane, Yellow Wolfsbane, Yellow Monkshoo, is a very poisonous one, often used in the past as a way of killing wolves through arrowheads dipped in a liquid prepared of the herb. In fact, it seems to be so poisonous that it can kill a person just by absorption through the skin (in a cut or something like that or if rubbed in sensitive areas) and some people reported they felt unwell after just smelling the plant. Accidental ingestion is fatal, but very rare, since it has a very unpleasant taste.
Those poor wolves didn't stand a chance!