During this Samhain season, with its full harvest moon, you may run across the occasional werewolf.
If you should choose to run with the werewolves, read no further.
But if you have need of a antidote to lycanthropy, or a protective spell to guard against their nibbles, wolfsbane will suffice.
The ancient Roman physician Dioscorides referred to wolfsbane as lycotonum. Today it is also known as monkshood or aconite. It belongs to the buttercup family, and there are over 250 varieties. The flowers can be blue, purple, pink or white and it grows profusely across the northern hemisphere, particularily in Europe (probably in little remote east European villages, at night and in fog, right next to gypsy women that warn of werewolves...).
Aconite was (is?) known as "the quintessential plant of the occult". It was acknowledged to induce the lycanthropic condition (i.e. the wolfman transformation). Mixed with belladonna, a witch might even create a flying ointment.
At the same time, it was said to be the only antidote that reverses the condition, or outright kills a werewolf.
Fact: The seeds, leaves and roots contain aconitine, a deadly poison that slows the heart rate, decreases blood pressure and creates a numbing pain. It is extremely dangerous if ingested or even with skin contact if there are small cuts. (So don't do it.)
During the 1500-1600's Europe was gripped with a plague of werewolves. Humans accused of being werewolves were hunted down with arrows dipped in acontine, while traps baited with meat laced with the poison. If the acontine didn't kill them, burning at the stake usually did.
A brief recap:
Wolfsbane is beautiful, easy to grow, and really, really poisonous.
Wolfsbane kills werewolves.
But really, why would you want to? Seriously, what'd werewolves ever do to you? Leave 'em alone...