Pacific poison-oak and western poison-ivy : identification and management
Hulting, Andrew Gerald
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Pacific poison-oak is common in western Oregon and Washington. Its near relative, western poison-ivy, is found in eastern Oregon and Washington, throughout Idaho, and eastward. These plants are so similar in their appearance, growth, effects on humans, and responses to control efforts that their common names are often interchanged. Pacific poison-oak and western poison-ivy often grow in fencerows, waste areas, evergreen forests, woodland savannahs, hill pastures, clear-cut forests, stream banks, wetlands, and rocky canyons. Both plants are native to the Pacific Northwest. Outdoor recreationists, land managers, forest and conservation workers, and wildland firefighters are most frequently exposed to these plants. All parts of Pacific poison-oak and western poison-ivy plants (except the pollen) contain an oily substance, urushiol that is present throughout the entire year. Exposure to urushiol can cause an allergic contact dermatitis reaction that includes painful irritation and blistering of the skin and, if inhaled in smoke, the lungs. Individual reactions vary from extreme susceptibility to near immunity. Many people are immune when young but suddenly or gradually become sensitive with age, possibly due to sensitization through repeated exposure. These two plants can substantially limit the use and enjoyment of our natural environment.