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What Is a Poison Ivy Plant?

A man with poison ivy blisters on his hand.
Exposure to poison ivy may cause a red, itchy rash to appear.
Using an oatmeal based lotion can soothe a poison ivy rash.
Poison ivy.
Poison ivy can cause severe itching.
A woman applying an anti-itch cream.
Article Details
  • Written By: Ken Black
  • Edited By: Andrew Jones
  • Last Modified Date: 02 December 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
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A poison ivy plant is a plant that is generally considered a bothersome weed in many areas. The plant has two different subspecies, known as eastern poison ivy (toxicodendron radicans) and western poison ivy (toxicodendron rydbergii). The plant has the ability to cause severe skin irritation on those who get touch it. This irritation often has to be treated with anti-itch medications in order for the victim to be as comfortable as possible.

The two different subspecies of poison ivy are very similar to each other, each typically having a characteristic grouping of three leaflets on one stem that is attached to a larger stem. Despite the familiar grouping of three leaves, the poison ivy plant can have as many as nine leaflets per stem, so simply looking for three leaves is not an entirely effective poison ivy plant identification strategy. The plant typically grows near water sources, such as lakes and streams, and also prefers partial shade to full shade. It grows on vines and produces flowers and berries.

The irritating chemical in a poison ivy plant is a substance known as urushiol. This is a protective feature of plants in the genus toxicodendron, which used to be part of the genus rhus. Urushiol is mainly meant to protect plants from being eaten, as consuming it can be toxic for many plant eaters. In cases where it is touched, the poison ivy plant can cause a very different reaction.

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When the poison ivy plant is touched, its defense mechanisms go into motion, producing the urushiol. This chemical then gets onto the skin of the victim, where it attaches to a protein in skin cells. Once that happens, the body's immune system no longer recognizes the skin cells as being normal cells and begins to attack them, causing the irritation, itchiness and even blisters. The attack may continue until the urushiol is completely gone. Symptoms generally begin 24 to 48 hours after contact with the plant.

The treatment of poison ivy includes topical anti-itch ointments that should help soothe the itch, along with a specialized soap known as Fels Naptha®. This soap contains petroleum distillates that actually dissolve the urushiol, and therefore minimizes the damage to neighboring cells. This soap is in bar form and may be located in the laundry section of grocery stores.

Herbicide can kill poison ivy plants, but it may take several applications as the plant may regrow from roots several times. Care should be taken when removing the dead plants, as urushiol can remain on the plant up to five years after it has died. The chemical is still just as potent, even if the plant that produced it is no longer alive.

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