Beware the dreaded urushiol, the oil found in poison ivy (pictured), oak and sumac!

Beware the dreaded urushiol, the oil found in poison ivy (pictured), oak and sumac!

Unwelcome natives lead to itchy outing

BY Kristal Walsh, private lands biologist

Florida Fish and Wildlife Conservation Commission

This year’s warm winter temperatures have many of us itching to get outside for camping, hiking, wildlife viewing and other recreational activities. As trees and plants begin to leaf out and spring’s early blooms draw us to showy forest trails, wildlife management areas and parks, consider the following information on noxious plants so you aren’t itching to get back home! 

As a natural resources’ professional, I spend a lot of time educating the public about how invasive plant species threaten our native wildlife and habitats. So often, discussion about native plants like poison ivy (the most common), poison oak and poison sumac – which all pose a threat of a different kind – is overlooked. 

These three common Florida woody plants contain an oil called urushiol that can cause a severe rash resulting from direct contact with any part of the plants. Symptoms also can occur from indirect contact from objects like clothing, shoes or even pets which have encountered the plants. 

We are born with varying sensitivity to urushiol, and repeated exposure to the source can lead to greater sensitivity. Approximately 15 percent of people are completely resistant, but many know all too well the miserable experience that accompanies the skin irritation caused by these plants. 

The first signs may appear within eight hours of contact and a severe rash can last up to five weeks. Over the counter treatments such as calamine lotion may help temporarily, but in some cases a physician’s visit is required to treat the rash. 


• Learn to identify the plants – Catch phrases like “Leaves of three, let them be” apply to poison ivy and poison oak and help us to identify them at the beginner’s level. But plants such as blackberry also have three leaves and can occupy the same general location as these plants, which complicates things. 

Each of these plants also loses their leaves in the winter, making them very difficult to identify. But remember: even in winter when no leaves appear, the urushiol oil is still present and can cause an allergic reaction. Your I.D. skills must be taken up a notch if you frequent the outdoors. 

Virginia creeper also commonly is mistaken for poison ivy, because it too is a vine and turns a brilliant red color in the fall, but it has a cluster of five leaves instead of three. To make matters worse, this look-alike has also been known to cause a contact dermatitis in a very small percentage of the population because of needle-like calcium oxalate crystals called raphides, which can be found on the leaves and berries. 

Poison ivy, a member of the cashew family, also is deceiving because it may appear as a shrub or a trailing or climbing vine in different locations at different stages of growth. To learn more about identification of these plants, go to 

• Location, location, location – Be familiar with the areas where these plants grow. While poison ivy can be found in almost every state, you probably won’t find this plant in dry ecosystems like sandhills or beach dunes. You will, however, find it in part sun to shade in moist to wet areas, often near the edge of a road or trail. Similarly, poison sumac thrives in moist soils and in the forest understory. Alternatively, poison oak thrives in sunny, dry locations. 

• Protection and treatment – If you will be in an area where you may encounter these plants or know you are susceptible to an allergic reaction, take precautions by wearing close-toed shoes or boots, long pants and long sleeves. Always err on the side of caution if you are unsure of the plant’s identity and avoid it. 

If you come in contact with one of these plants, wash the affected area with soap and water immediately, or at least as soon as possible. Clean all other tools, shoes and other items that may have been affected and wash all your clothes separately from other laundry. Even if you’re not sure, it’s safer to shower after a hike and take these other measures since you may have encountered these plants without knowing you did.

The Florida Fish and Wildlife Conservation Commission’s Landowner Assistance Program works cooperatively with private landowners in Florida who want to restore and conserve fish and wildlife and their habitats on their property. To learn more about managing wildlife and habitat on your property, check out our habitat how-to section at the FWC’s Landowner Assistance Program by going to You can also contact a LAP regional biologist for technical assistance.

Come visit the FWC’s wildlife management areas to experience and have fun in Florida’s great outdoors: