Identify and Take Care of Poisonous Plants
Learn how to keep these poisonous plants out of your garden.
Most people are familiar with poison ivy, but they often don’t know about poison oak, poison sumac, and other toxic plants that may be growing in their yards or nearby. Learn how to spot these plants and what to do about them.
Poison Ivy, Oak, and Sumac
Poison ivy, which grows mainly east of the Rockies, is one of the most poisonous plants. Poison oak, found mostly in the West, and sumac, found mostly in the Southeast, are less common. All three contain urushiol, an oily resin in the plant sap that causes an itchy rash.
“Leaves of three, let it be” is a common admonition for avoiding poison ivy, but it’s not quite that simple. Poison ivy blooms in springtime and bears white berries in the late summer. Depending on the time of year, it may have more than three leaves, and they may be shiny or dull, red or green. In winter, when the vines have no identifying leaves, the plant is still poisonous. Here is a more in-depth guide to identifying poison ivy.
Poison oak also has three leaves together, but they are lobbed at the edges, and the plant usually grows as a shrub rather than a vine.
Poison sumac is a small tree or shrub that has pairs of pointed leaves. Though it grows mainly in the South, it also thrives in freshwater wetlands in northern areas.
There is a wide range of sensitivity to urushiol; some people can handle plants that contain it without having any reaction, while others have a severe reaction at the slightest contact. Even if you haven’t had problems in the past, don’t assume that you’re immune. Remember, too, that a reaction may occur immediately or take up to 25 days to develop.
If you suspect that you have come in contact with poison ivy, oak, or sumac, wash the affected area thoroughly with cold water and a strong soap or detergent, such as dishwashing liquid. After you have cleaned the skin in this way, apply rubbing alcohol to the area to remove any remaining sap.
You can spread urushiol to other parts of the body, not by scratching the affected area but by touching the sap on pets, clothes, garden tools, or other objects, often long after the initial exposure. Immediately after any possible contact with poison ivy, wash tools and launder clothing in hot, soapy water. Make sure children change clothes after hiking or playing in an area that might have poison ivy. Shampoo pets that may have touched the plant.
Getting Rid of Poison Ivy
The safest way to kill poison ivy is with a systemic herbicide that contains triclopyr. It may take several days and several applications for the vine to die. Follow the directions on the package and make sure you apply it only to the poison ivy.
Even when the poison ivy plant is dormant in winter, or dead, the rash-causing urushiol persists. Whenever you remove vines that you haven’t positively identified as safe, take precautions, as if they were poison ivy.
Large poison ivy vines that climb up a tree or building should be cut at the bottom and treated with a herbicide. Wear gloves when cutting the vines, and be sure to wash all tools and clothes thoroughly after you are finished.
Never burn poison ivy or any urishiol-containing plant. If you do, you may inhale poison in the smoke, which can cause a severe lung reaction. Instead, seal the plants in a plastic bag with other trash headed for a landfill.
Common Poisonous Plants
Poison ivy, oak, and sumac are not the only poisonous plants found in yards and gardens. Some plants are poisonous when touched; they include four o’clock, sagebrush, stinging nettles, and yew. The following plants or plant parts are toxic when ingested, and those marked with asterisks* are especially dangerous.
*Dumbcane (or Dieffenbachia)
Holly leaves and berries
Lily of the valley
Morning glory seeds
*Nightshade (or Belladonna), especially berries
*Poisonous mushrooms, especially Amanita
Potato sprouts, roots, and vines