Of the literally hundreds of plant species that qualify as weeds, remarkably few are at all harmful if touched. For that much, at least, we can be thankful! Unfortunately, three notable exceptions to this rule are so widespread throughout North America that many of us will unwittingly stumble upon at least one of them at some point in our lives. These weeds are poison ivy, poison oak and poison sumac, all of which are closely related and possess a potent natural defense that renders them all but untouchable.

Since the only sure means of preventing a nasty rash is to avoid contact with the plants that cause it, you should make it your business to learn how to recognize poison ivy, poison oak and poison sumac by sight. Then, keep your eyes peeled and keep your hands off whenever you encounter suspicious-looking growth.