Identifying, treating and removing poison oak, ivy and sumac

The USDA's Natural Resources Conservation Service recognizes fifteen species of poison ivy, poison oak and poison sumac throughout the known world and five of those grow natively in North America.

These plants are found in wooded areas and tend to blend with more innocuous ground cover. While they aren't technically poisonous, the urushiol in them does incite allergic reactions in most who come in contact with their leaves, stems or roots.

The effects take hold from exposure to all parts of the plant, especially the sap, to someone with an allergy vary from swelling and redness to a rash that lasts two to three uncomfortable weeks. Scratching won't spread the rash, but it may cause infection and definitely will cause scarring.

While pets can usually make contact without adverse reactions, the oil can stick to their fur and then pets unwillingly act as carriers.

Those who are sensitive to poison ivy and sumac can grow even more sensitive the more they come in contact with it, so identifying and preventing exposure is best practice.

Identifying Toxicodendron

The poison ivies are sometimes included in the genus Rhus with sumacs, but are more frequently placed in their own genus, Toxicodendron (Greek for poisonous tree).

Western poison ivy tends to grow as a low shrub rather than a vine, like its eastern relative. Poison sumac is more often a shrub or tree.

Poison ivy always grows in a three leaf cluster, with one on each side and another distinctly in the center. Poison oak looks similar, but the leaves tend to grow even larger with more rounded tips instead of points.

Poison sumac is a bit further from the norm with as many as three, five or seven leaves per stem. This orientation of the leaf clusters is its similarly distinguishing characteristic with seven or thirteen leaves instead of poison oak's three or five. Every branch has a single leaf at each stem's end. Mind the time-tested adage, leaves of three, let it be.

Safe removal or plants:

When it comes to removing poison ivy, the best method is the most thorough. Dressed in long sleeves, pants and thick gloves, remove the plant's leaves, stems and all of the roots. Put it all in a bag, and put that bag in the garbage.

Gardeners are advised to not burn the leaves. (Don't burn anything as there is a burn ban in effect until at least September 15th.) But especially don't burn the leaves of a potentially noxious plant. Inhaling urushiol burns eyes, nose and throat, and may require medical treatment.

The best way to remove the plant without touching it involves enlisting the help of a goat or cow. They, like pets, can endure contact without any itchy side effects. The difference is, they enjoy munching on it. This, of course, only removes the part of the plant that is visible, leaving the roots intact.

Digging out the roots is a bit safer than touching the leaves. Another option is mixing a concoction of 1 cup salt, 1 gallon vinegar, and 8-10 drops of liquid dish soap. Dissolve the salt in the vinegar over low heat. Once cooled, add liquid dish soap and load the mixture into a spray bottle, or pour directly over the afflicted area. This combination will kill all the surrounding vegetation, so accuracy is key.

Using chemicals to kill the plant without removing its stalks and stems is not recommended because even once the plant is dead, the oils within it remain active.

Rather than risk killing nearby plants, another way to rid the area of poison ivy is to cultivate something even more pervasive such as grass seed. With proper tending the grass will starve the poison ivy roots, preventing its return.

Urushiol is not without its use, though. Both genera of poison ivies belong to the Anacardiaceae, a plant family that includes mango, cashews, pistachios, and a number of other species of edible trees and shrubs that are often notable for the production of resins. Japanese, as well as Chinese and Korean artisans derive lacquer from the sap.

Treatment after contact:

Dr. Jacqueline Mohan and colleagues at Duke University have found that poison ivy plants grown under higher concentrations of carbon dioxide were found to produce significantly more unsaturated urushiol-the form that is most virulent to humans, and to grow faster. They conclude that poison ivy will become more widespread, aggressive, and toxic in the projected warmer world of the future.

Because of the oil's sticky nature, it can be difficult to remove, especially from clothing. Soap, water, or rubbing alcohol are allies in expelling it. Be sure to hose down every tool used, boots, and gloves that make contact otherwise the rash might be recurring.

Natural remedies include juices from jewelweed, also known as Impatiens capensis, calamine lotion and aloe vera gel to effectively treat the itching, burning rash of poison ivy.

DC Comics fans may note that Poison Ivy is also a fictional supervillain botanist who, despite her ultimately good environmentalist intentions, should probably also be avoided.