Oaks Without an Acorn and Vines of Deadly Hue

Poison oak grows in many areas in California and should be avoided at all times. Eradicating does not include burning which can spread the poison through the air.

By Clinton S. Powell, Naturalist

New, emerging leaves in trees are pure beauty. Pink is the dominant color, and with a gentle breeze, the mountain waves in a blend of candy canes and evergreens. But one vibrant plant is both beautiful and deadly.

With common sense and education, however, the deciduous shrub or vine known as poison oak — or Toxicodendron — turns into a mere annoyance.

Toxico is Latin for toxic

and dendron is Latin for tree. Poison oak is not poisonous, and it is not a tree or related to the oak family.

Poison oak grows throughout the county, usually westward from the mountains to the lower foothills. At present, our mountains are radiant with the deep purple growth.

The oil of poison oak yields an allergic contact dermatitis. The toxic, oily sap called urushiol spreads easily by touching any portion of the plant. If you pry out roots or upper growth with your hands, you could be in a doctor’s office in two hours. Wearing gloves helps keep the active oils off your skin, but these gloves should be worn only once.

Poison oak is most hazardous when the temperature is 75 degrees Fahrenheit or higher and when the humidity is 50 percent or higher. When both conditions occur, this plant is dangerous to inhale. I’ve seen photographs showing the volatile insidious oils steaming out of a rapidly growing plant under hot, humid conditions.

Poison oak can affect you directly or indirectly. If you have a dog or a cat and they walk through poison oak, the oil will be on their fur. I’ve never heard of a dog or cat having a problem with it, but if they hop in your lap or sleep on your couch, you could be in for problems.

Horses and cattle aren’t bothered by it. Chickens scratch and dig around this plant but it doesn’t bother them, either. Personally, I don’t let horses, cattle or chickens hop in my lap or sleep on the couch.

In rural Mexico, chickens are seen everywhere. Chickens scratch through shrubs, feeding on grubs and grass and are often kept in the yard. Youngsters learn by seeing, so tell them, “These are chickens, they are scratching in poison oak,” and “Don’t gather eggs in the shrubs.”

If you come in contact with poison oak, take off all your clothes, put them in a plastic bag, then wash them. Of course, walking or driving home naked is not advised.

Poison oak can be a vine 4 inches in diameter and 20 feet high or a shrub 4 feet high that spreads in all directions. Teach youngsters to avoid the vine or they won’t be allowed in the house or will have to walk home. This sounds cruel, but the volatile oils spread like hot syrup.

One way to identify poison oak is: “leaves of three, don’t touch me.” When deciduous, it blends in with many similar plants, so take your time, know it, avoid it.

Often growing adjacent to poison oak is the deciduous shrub known as basket bush, or Rhus trilobata. Poison oak and basket bush are both in the sumac family. Many years ago, a fine taxonomist changed poison oak from Rhus to Toxicodendron; best Latin name I know.

Eliminating poison oak on your property is serious and deadly. Evaluate the land; if too much poison oak is present, you might never eradicate it. Perhaps you should not live there. Never, ever burn the leaves; anyone downwind can inhale the fumes. Leave poison oak alone; hire a professional.

Poison oak also is a big problem in early autumn. The leaves turn into a beautiful orange-reddish color. Yes, I have seen people cutting it for autumn color. Good idea, wrong plant.

Always be careful while walking through brush at any time of year. Don’t let dogs and cats roll in it. And don’t roll in it yourself, either.

The California Poison Control System (CPCS) serves the people of California with a single, toll-free emergency hotline number 1-800-876-4766. www.calpoison.org/public/home.html