What Makes Poison Ivy Poisonous and How Does Urushiol Irritate the Skin and Cause an Itchy Rash?
Sometimes there are nice correlations between an organism’s defenses and its enemies, but in the case of poison ivy, any such connection is a puzzle. Poison ivy is toxic to humans and a few higher primates and that’s it. As close a relative as the rhesus monkey, for example, is normally not sensitive to it. Fossil ancestors of p
