Poison Ivy

General Information
The plant that we know as Poison Ivy is actually a weed that is a member of the Anacardiaceae family. While not actually a poison, it triggers an allergic reaction that causes contact dermatitis. The poison ivy plant is widespread and can be found nearly everywhere in the United States and in Southern Canada. It is found in wet areas, including flood lands and riverbanks, as well as on the outskirts of forested areas.

Poison Ivy Plant
Poison Ivy Plant

Scientific Information
Scientifically, Poison Ivy is not actually ivy, it is a woody vine. It is a vascular seed plant that plant that produces flowers. It falls into the Anacardiaceae Family, and the Toxicodendron Genus. This is the genus of poison oak, which shares many characteristics with poison ivy. The specific species is Toxicodendron radicans, which is actually the Eastern Poison Ivy. The Eastern Poison Ivy and Western Poison Ivy are extremely similar, with the only major difference being where they are found.

The Scientific Breakdown of the Species Toxicodendron radicans.
Plantae – Plants
Tracheobionta – Vascular plants
Spermatophyta – Seed plants
Magnoliophyta – Flowering plants
Magnoliopsida – Dicotyledons
Anacardiaceae – Sumac family
Toxicodendron – poison oak
Toxicodendron radicans – eastern poison ivy

Physical Description
The Poison Ivy leaves come in groups of three, and each leaf ranges in size from one inch to three inches. The leaves of the plant are deciduous, which means that they fall off at maturity. Poison Ivy flowers in late spring and early summer and produces small berries which are a drupe fruit. The leaves change color from green to orange to red before they finally fall off in late fall. When recognizing the poison ivy plant, people usually look for the group of three leaves that have smooth edges and a smooth surface. Depending on the time of year, berries may or may not be present.

Poison Ivy Leaves
Poison Ivy with Berries

Geographic Distribution
Poison Ivy actually refers to several different types of very similar Toxicodendron species. Eastern Poison Ivy (Toxicodendron radicans) is found, not suprisingly, in the Eastern United States and Canada. Western Poison Ivy (Toxicodendron rydbergii) is found in the Western United States and Canada. Poison Ivy can be found in nearly every U.S. state, with the only exceptions being California, Hawaii and Alaska.

Poison Ivy can grow in a variety of different climates and soil types. It can grow in rocky areas as well as very wet areas and nearly everything in between. Poison Ivy has become much more common over the past several centuries. A leading cause of its growth has been suburban sprawl into areas that were previously home to wildlife which has increased the amount of contact between humans and the plant. Poison Ivy is native to North America and is not found in large quantities on any other continent.

Poison Ivy Distrubution

Allergy Information
Poison Ivy is best known for the rash that it causes, called contact dermatitis. It is estimated that seventy to eighty percent of people who come into contact with the plant develop some form of contact dermatitis. Once exposed, those who do develop a reaction will exhibit an itchy red rash usually within a day or two that can last for a week or more. Usually anti-itch cream can be applied to help with the itch and the rash goes away itself, however in about ten percent of cases the reaction is severe enough to require medical attention.

The oil urushiol is the substance that actually causes the allergic reaction. Urushiol is found in all parts of the plant: the leaves, stem, roots, flowers and berries. It is present in the plant year round, but people are more susceptible to it in the spring and summer when the leaves are more easily bruised. Urushiol can travel through the air and on any object that it comes in contact with. Direct contact with urushiol is not necessary for a rash to develop; often touching clothing or another object that has been in contact with poison ivy is enough to develop a rash. For example, a garden tool that touched poison ivy and then touched by a human could cause the rash. Urushiol can also travel through the air, so if poison ivy is burned and the fumes are inhaled it can be very irritating to the eyes and respiratory system.

Contact Dermatitis & Treatment
Contact Dermatitis, the name of the rash that is caused by poison ivy, usually develops within several hours of contact. It causes irritation and severe itching and often small blisters that are raised from the skin. In most cases, the rash will be very itchy but is not usually harmful. The blisters do not contain urushiol and therefore cannot spread the rash. Contact Dermatitis usually persists for about one to two weeks and eventually goes away on its own. However, in extreme situations medical assistance may be needed. This is necessary in about ten percent of cases, usually to people who pre-existing medical or skin conditions. A doctor can prescribe steroids to help the swelling of the blisters go down and certain forms of anti-itch cream.
Contact Dermatitis

Anti-itch creams are a popular way to help contain the persistent itching. Homemade remedies such a oatmeal baths are also an option. This video features Dr. Doris Day, a dermatologist who shows some examples of anti-itch products as well as a remedy that can be made at home.

Other Uses
In the early twentieth century scientists realized how harmful poison ivy was if its fumes were inhaled. World War I was taking place and they realized that if they could create a gas that had a similar effect as poison ivy, they would be able to inflict serious damage on enemies. Therefore, poison ivy can be attributed as the inspiration for mustard gas and other toxic gases that were used during World War I (Poison Ivy and Its Relatives).

Poison Ivy can also be used in a number of herbal and homeopathic remedies. Some claim that it can be used in a mixture that helps to treat arthritis.

Some people feel that you can build up a tolerance to poison ivy by eating some of the leaves in early spring when they contain very little urushiol. You would start by eating one leaf a day and then slowly build up your dosage, with the idea being that you would ingest a tiny amount of urushiol at the beginning and then once the urushiol became more prevalent in the plant further into the spring, you would have built up a tolerance and would not be bothered by it (Poison Ivy and Its Relatives). This idea was mentioned in several different places but everywhere it was mentioned explicitly stated that this was not the best way to go about treating poison ivy and had a very high rick of backfiring.

Poison Ivy is not totally negative. When planted it can help reduce erosion of topsoil, and it is an important food source for many birds and mammals because urushiol does not affect them the same way that it affects humans.

Works Cited

"How to Treat Poison Ivy." Web. 6 Dec. 2009. http://www.youtube.com/watch?v=nqKfltowxL0

Levetin, Estelle, and Karen McMahon. Plants and Society. New York: McGraw-Hill Companies, 2007. Print.

"Poison Ivy." University of Connecticut: Integrated Pest Management. Web. 6 Dec. 2009. http://www.ipm.uconn.edu/IPM/homegrnd/htms/poisivy2.htm

"Poison Ivy." Wikipedia. Web. 6 Dec. 2009. http://en.wikipedia.org/wiki/Poison_ivy

"Poison Ivy and Its Relatives." Web. 6 Dec. 2009. http://www.wildmanstevebrill.com/Plants.Folder/Poison%20Ivy.html

"Poison Ivy, Oak and Sumac Information Center." Web. 30 Nov. 2009. http://poisonivy.aesir.com/view

"Poison Ivy Rash." About.com Pediatrics. Web. 6 Dec. 2009. http://pediatrics.about.com/od/poisonivy/ig/Poison-Ivy-Pictures/

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