In pop culture, poison ivy is a symbol of an obnoxious weed because, despite its unthreatening looks, it gives a highly unpleasant contact rash to the unfortunate person who touches it. Still, it is commonly eaten by many animals, and the seeds are a favorite with birds. The leaves turn bright red in fall. Its sister species, Western poison ivy (Toxicodendron rydbergii), is not considered to be invasive in the United States, but is noxious in Australia and New Zealand.