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Poison ivy

This article deals with the plant Poison ivy. For the article on the member of punk rock band The Cramps with this stage name name see Poison Ivy . There was also a popular song from the 1950s named Poison Ivy.
Poison ivy

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Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Sapindales
Family: Anacardiaceae
Genus: Toxicodendron
Species: radicans
Binomial name
Toxicodendron radicans
Poison ivy (Toxicodendron radicans), in the family Anacardiaceae, is a woody vine that is well-known for its ability to produce urushiol, a skin irritant which for most people will cause an agonizing, itching rash.

Poison ivy grows vigorously throughout much of North America, but particularly in the American Midwest. It can grow as a shrub up to about four feet tall, or as a groundcover four to ten inches high, or as a climbing vine on any and every support. Older vines on substantial supports send out lateral branches that may at first be mistaken for tree limbs.

Poison ivy is apparently far more common now than when the Europeans first entered North America, because it has profited immensely from the "edge effect", enabling it to form lush colonies in such places.

Table of contents

How to recognize poison ivy

The leaves are compound with three leaflets, giving rise to the doggerel, "Leaflets three, let it be." The berries (actually drupes) are a grayish-white color and are a favorite winter food of some birds.

Poison ivy looks like ivy. Each tendril of ivy ends in three leaves which are almond shaped. Color ranges from light green (usually the younger leaves) to dark green (mature leaves). Leaves can be as long as 10 or 12 inches long, but are usually 4-6 inches long when they are mature. Each leaf has a FEW teeth along its edge, and the leaf surface is SMOOTH. To compare, blackberry and raspberry leaves also come in threes, but they have MANY teeth along the leaf edge, and the top surface of their leaves are very wrinkled where the veins are. The stem and vine are smooth, brown and woody, while blackberry stems are green with thorns.

Virginia creeper[?], Parthenocissus quinquefolia, vine can look like poison ivy. The younger leaves can come in groups of three but have a few more serrations along the leaf edge, and the leaf surface is somewhat wrinkled. Virginia creeper and poison ivy very often grow together, even on the same tree.

Poison oak leaves also come in threes on the end of a stem, but each leaf is shaped somewhat like an oak leaf.

Poison ivy likes shady areas with only a little sun. They tend to climb the trunks of trees, and can spread rapidly along the ground.

If the poison ivy is growing up a tree look at the fine. It will be smooth with no ladder like roots clinging to the tree. (Some sources report that poison ivy does have these ladder like roots.)

Beware of dead poison ivy: it still has plenty of urushiol, and will give the same effect. Compare the thick vines of grape: no rootlets visible, to the vines of poison ivy: so many rootlets that the stem going up a tree looks furry.


The skin rash, featuring fluid-filled blisters and reddened areas that itch intensely, is caused by an irritating oil, urushiol. Urushiol binds to skin cell walls, changing their configuration, so that the body's immune system no longer recognizes these cells as belonging to the body and attacks them as foreign. Some people are susceptible to the rash, and others aren't, but reactions can change during a person's lifetime. Someone who was formerly not subject to it may become very sensitive, and vice versa.

Normally, it takes about twenty-four hours for the rash to first appear, though it may worsen during the next few days and may appear to spread, when in fact what is happening is that areas that received a lesser dose are latently reacting. The rash takes one to two weeks to run its course, but normally does not leave scars. Severe cases will have small (1-2mm) white fluid-filled blisters on the skin.


When a person has been in contact with poison ivy, there are several measures that may be taken to prevent or lessen a rash. One of these is to find plants of jewelweed, Impatiens species, and to take the whole plant, crush it into a ball, and vigorously rub it into the exposed area. Or,crush some jewelweed stems in a container, and use a cotton ball to soak up the juice. Spread it on the rash as soon as possible.

There is an unfortunate story that is often repeated is that "Wherever poison ivy is found, jewelweed grows close by." This is completely untrue; poison ivy grows in a wide variety of habitats, while jewelweed is restricted to moist bottomlands and valleys with rich soil. The reverse is true — wherever jewelweed is found, poison ivy is usually close by. Jewelweed grows in sunny wet areas, like ditches on the roadside. The 1 cm (1/2 inch) long flowers are shaped like a shoe. Some plants have orange flowers with dark spots. Some plants have plain yellow flowers.

Another method is to take mud, preferably clay mud, and vigorously rub it in. Affected people can also use either laundry detergents or strong soap to scrub the area before the rash appears.

Urishiol is an oil and is not washed off by plain water. People have had success in lessening the rash by wiping the area clean with alcohol, or mild soap, in order to break down the oil. However, laundry detergent or Fels-Naphtha soap work much better, but vigorous rubbing is necessary. If you are desperate, you could also try wiping the area with other solvents, like acetone (nail polish remover). Some article advise against this because it will deprive your skin of moisturizers to protect you from the oil. However, the oil is obviously having an effect on your skin, and you can always put lotion on the area later.

One treatment is steroids, as a shot or pills, to control the itching. Another treatment is calamine lotion over the affected area, apply as needed. Other topical treatments include: liquid Benedryl or any other anti-itch cream/oil. A bath with baking soda also helps some people. Soak in a warm (not hot) bath for 30 minutes. Using a hot bath would cause one's pores to open and let more urushiol attack the skin.


Preventing exposure to poison ivy involves ways of preventing the oil from getting on the skin. - Wear long clothing, avoid any plants that look like poison ivy. - If you must wear short clothing, put thick lotion on areas that may be exposed to poison ivy, like the legs. A suntan oil may work even better. - If you handle tools that have touched it, wear gloves, then wipe the tools with alcohol immediately after using them, or throw them away.

Killing the poison ivy plant

Poison ivy is EXTREMELY hardy and very resistant to poisons. Some herbicides will not destroy the roots, allowing the plant to grow back the following year. Roundup and other grass killers do not affect poison ivy. Some people recommend using a brush killer.

You can also physically pull up all the vines and roots but you must wear gloves and pants and a long sleeve shirt. DO NOT BURN poison ivy. The smoke particles carry the irritant and allow it to be inhaled; people that are extremely sensitive to poison ivy could die. Wrap the plants in a good garbage bag and bury them or dispose of them in a landfill.

Another solution is mixing 1/4 cup salt in 1 quart of water and put in a spray bottle. Spray the leaves of the poison ivy with this solution. NOTE: this will possibly kill any surrounding plant life if it gets a significant amount of salt water on it.

Yet another solution which has worked is sprinkling Borax on the leaves. It will take about 3 weeks for the leaves to die back. It may be necessary to repeat this treatment for more than one growing season.

See also:

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