By Gita M. Smith
Photo Courtesy USFWS
Poison ivy, poison oak and poison sumac are the best known North American plants that bite.They grow almost everywhere in the United States, except Hawaii, Alaska and some desert areas of Nevada.
Poison ivy usually grows east of the Rocky Mountains and in Canada. Poison oak grows in the Western United States, Canada and Mexico and in the southeastern states. Poison sumac grows in the eastern states and Southern Canada.
Half of all Americans are allergic to these plants. Contact with them causes a painful, itchy rash. Swelling, runny blisters and redness are the symptoms that may follow if you are allergic to these plants.
Brushing up against poison ivy, poison oak and poison sumac are most likely to cause problems in the spring and summer when all parts – from roots to leaf – are full of sap. The sap can even become airborne in smoke when someone is burning the shoots or vines. If you breathe in the smoke, it can irritate the linings of your nose, mouth and airways to the lungs.
Photo Courtesy of USDA NRCS Wetland Science Institute
And, plants that have died are almost as dangerous as live plants, so if you can get a rash from the plant, dead or alive.
Poison ivy wears many disguises, looking like a low plant or a vine, trailing along the ground or climbing to the top of the tallest tree. Watch for hair-like roots that grow from the side of older vines. Poison ivy can also appear as a woody shrub.
Remember this warning — Leaves of three, let it be.
Poison ivy’s 2-to 4-inch-long leaves are smooth or glossy on top and hairy underneath. It has white berries that grow near the base of the leaf stem in drooping clusters. These small fruits may be smooth or hairy, and you will see them from August to November. Rubbing the rash won't spread poison ivy to other parts of your body (or to another person).
Photo Courtesy US Department of Agriculture
You spread the rash only if urushiol oil – the sticky stuff that causes the rash – is on your hands.
Poison oak is usually found a shrub, and occasionally, a vine. Its shiny leaflets are lobed in an oak shape. The underside of poison oak leaves are paler green than that of poison ivy.
Like poison ivy, poison oak has white berries.
Poison sumac has a bad reputation, but it’s not all bad. Some sumac is not poisonous at all. The ones with red berries are safe. The one to worry about, poison sumac, grows as a shrub or a small tree. It ranges from 6 to 20 feet tall and has hairless buds and twigs. It has pin-shaped leaves, with a long center stem and seven to 13 leaflets.
Be on the lookout for shrubby sumac with smooth or hairy white berries in hanging clusters. They grow in wet areas, and you should avoid them. Touching any part of this plant can cause itching and blisters.
Learn more and see more photos of poison ivy, poison oak and sumac at http://poisonivy.aesir.com/view/pictures.html