Busting myths about poison ivy, from the Harvard Health Letter

Poison ivy poses real problems to gardeners and outdoor enthusiasts. But some of the "facts" that people know about this plant are really myths, reports the May 2013 Harvard Health Letter.

Plants employ a variety of defenses to protect themselves. Poison ivy, poison oak, and poison sumac secrete an oil that some people are allergic to. Contact with the oil triggers an allergic reaction that shows up in two to 10 days as a red, swollen, itchy, blistering rash known as allergic contact dermatitis.