Dangerous leaves!
"Leaves of three - let it be!" aptly describes this woody vine with 2-4" leaflets in groups of three. The center leaf has a longer stem than the other two. Poison ivy clings to tree trunks and other vertical surfaces with hair-like aerial rootlets that grow out of the stem. If a climbing surface isn't available, poison ivy will grow as a free standing shrub. The leaves of poison ivy turn shades of red and purple in fall. Poison ivy is caused by an allergic reaction (allergic contact dermatitis) to the oily coating that covers of these plants. The resinous coating is called "urushiol". These are called Rhus plants after the old scientific name (it was changed to toxidendron). A person doesn't have to come in direct contact with the leaves, roots, or branches of Rhus plants to get the rash. One can get it from contaminated clothing. Even in winter the leafless stems and vines can cause the familiar skin rash. No one is born with sensitivity to Poison ivy, but if exposed enough most people become sensitized at some time and remain allergic. A sensitivity can change at any time. There's no way to desensitize people allergic to Rhus plants. Dogs and other animals are not affected by poison ivy, but people can get the rash by petting a dog that's been exposed.
The rash itself is not contagious, and the fluid in the blisters does not spread the rash. Poison ivy dermatitis appears as soon as four hours or as long as 10 days after the exposure, depending on individual sensitivity and the amount exposure. As the rash appears, any sensitivity a person had begins to increase. One starts to react to the slightest traces of a few molecules on the skin. This causes the rash to appear to be spreading, even after treatment has begun. Poison ivy read more
