our humbling neighbor: an introduction to poison oak

by Kyle Pinjuv

​Like the grizzly bear, the wolf or the shark, plant and animal species in nature are often misunderstood. As humans, we occasionally focus our attention on the harm that these oft-maligned animals can cause to ourselves, our tents, our livestock or our beloved surfboards, forgetting that every plant and animal in our natural world plays a very important role in the balance of the greater ecosystem. So, how can we peacefully coexist with plants and animals that can cause us or our loved ones harm? We can learn more about them, of course.

More often than not, the process of education illuminates the dark, scary places in our minds and allows us to more freely (and safely) enjoy the natural world that surrounds us. In Sonoma County, we enjoy a beautiful, temperate Mediterranean climate with picturesque rolling hills and oak savannas as well as some of the most spectacular coastal landscapes in the country. But all landscapes come with challenges, Sonoma County’s included. Many of us have spent a day recreating or volunteering out on the land, only to wake up in the middle of the night itching and scratching with the despairing realization that we have been exposed to one of Sonoma County’s most infamous misunderstood species:

Poison oak (Toxicodendron diversilobum)​

This unfortunate yet attractive native — yes, native — deciduous shrub contains the same oil, urushiol (oo-roo-shee-ohl), found in poison ivy and poison sumac. From the Japanese word urushi, meaning “lacquer”, the oil found on the stems and leaves of the shrub causes a painful, itchy rash on the 85 percent of the population who are allergic to it. In 1624, explorer John Smith described his reaction upon first exposure to the urushiol oil on a poison ivy plant: “… being but touched, causeth rednesse, itching, and lastly blisters.” Indeed, John — as little as 1 billionth of a gram of the chemical is enough to cause a reaction in some people. Additionally, if you do not currently show symptoms after exposure, this does not mean you are not allergic. Sometimes the allergy is asymptomatic until you’re repeatedly exposed to it. Because continued exposure can result in sensitization, you should always take precautions when out in the field. Once on your shoes, clothing, tools, pets or bike, urushiol can be transferred from any object to your skin for years after exposure.

​This is a burden we humans have to bear. While we have little use for the plant (other than the aesthetic beauty of the fall foliage), poison oak has many benefits to other animal species. Poison oak shrubs offer shelter to fox squirrels while also providing food — the plant’s berries — in the spring. The California towhee builds its nests in the shrub and also feeds on the white berries. Large herbivores, such as deer (and even domestic goats), feed on the leaves and stems of the plant as well. These examples are just a few of the many. While it is easy to dismiss this plant as a nuisance — and trust me, after one or two exposures, it’s easy to do just that — it is important to step back and appreciate its benefits to our forest ecosystems. 

As humanity is continually humbled by the effects of the unassuming shrub found throughout the lowland forests of California, like it or not, poison oak is probably here to stay. Take precautions while spending time in areas known to have poison oak. Learn about the plant: how to avoid exposure, how to clean exposed clothes, tools, pets, skin; and how to treat a mild or severe reaction.
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I invite you to share your stories about treatment and prevention on poison oak exposure in the comments section below. Together, we can illuminate the dark and shed light on the realities of poison oak — all the while, helping one another avoid those “lastly” blisters.

​Kyle Pinjuv is an assistant stewardship project manager at Sonoma Land Trust.