A long time ago, poison ivy was considered a power plant. It was used by people throughout the Americas much like tobacco, smoked for hallucinations and healing ceremonies. As it gave the power to see the future, it was used wrongly, and because of it many battles were won and many died, and so the poison ivy transmuted itself to give rashes, so that it could no longer be used. It can not be smoked, or taken internally, in any form other than homeopathically. The more you have killed in your past lives, the more sensitive you are likely to be to poison ivy. Those who never killed are totally immune to it. It is not a punishment, but rather a booby trap. The more the wars of America rage, the more the ivy grows, and grows. It is good in this climate, and humans are encouraging its growth in preparation, to remind themselves in the future to kill less, and not at all.