Ivy: She with the Poisonous Tongue

Today we will spending a little time becoming acquainted with a plant called Toxicodendron radicans, or poison ivy. This is one of several species of plants in the United States that produce the poisonous chemical urushiol, others being poison oak and poison sumac.

Upon coming into contact with the skin, urushiol triggers an allergic reaction that results in severe itching, followed by inflammation and blisters. Between 15-30% of people display no symptoms to urushiol, while on the other hand, it may trigger an anaphylaxic shock is some. Not only can the chemical remain active for years, but the resin can be transferred to other objects which then cause a reaction upon handling. So should you enthusiastically  stomp on poison ivy with your boots, thinking you are safe from harm, just remember that when taking off those same boots you may get the oil on your hands.

You should never attempt to get rid of poison ivy by burning, as the inhaling the fumes can cause damage to the lining of the lungs. This is bad.

The Unholy Trinity

We all know that prevention is better than cure, and for that reason, we need to be able to identify the culprit. The first and most noticeable characteristic of poison ivy is that the leaflets are arranged in clusters of three. As the rhymes go, "Leaves of three, let them be." and "One, two three, don't touch me." Even when you can't positively identify the plant as Toxicodendron radicans, this characteristic alone should warrant caution. 

As for other characteristics, they include:

• an alternate leaf arrangement
• lack of thorns
• each cluster of leaflets growing on its own stem
• the two lateral leaflets occurring on very short petioles, while the central leaflet occurring on a much longer petiole
• the lateral leaflets often being distinctly lobed on one side of the leaflet and not on the other. 

There are several plants that can be mistaken for poison ivy, including the Virginia creeper (Parthenocissus quinquefoli) and Box-elder (Acer negundo). Take the photo below, which I took recently at Waterfall Glen Forest Preserve. When I initially spotted it, my first thought was "oooh, poison ivy!", but on closer inspection, you will notice that the leaf arrangement is opposite, not alternative.  This may indeed be a Box Elder sapling. While you are looking, say hello to the caterpillar.

So if you do inadvertently touch some poison ivy, what should you do?

First all of, before the urushiol is completely absorbed by the skin, you can wash the area with plenty of cold water. This will dilute the oil, and hopefully limit the reaction. Notice the word cold. Hot water will open up your pores and speed up absorption of the oil. You should note that 50% of the oil will be absorbed within 10 mins, so speed is of the essence.

Usually the rash will develop anywhere between 12 and 48 hours after contact with the plant, and can last for several weeks. To relieve the itching, you can:

• for the first few days, apply a corticosteroid cream . 
• apply calamine lotion. 
• take oral antihistamines. 
• place cool, wet compresses on the affected area for 15 to 30 minutes several times a day.

If the poison ivy has brushed against your clothes, then they will need to be washed. Using a regular laundry detergent, wash the contaminated clothes at highest recommended temperature. Do not overload the machine, and to be on the safe side, do not wash with any other clothes.