Here’s a picture of beautiful fall foliage in the oak woodland in Annadel Trione State Park in Northern California, and the striking plant is— poison oak! Lots of people suffer itchy rashes when exposed to the oil it contains, urushiol. The Native Americans who live where poison oak is found have long made use of it in basket-making, dyes for tattoos, and medicines. Apparently they developed some immunity to it, though they also made medicines to treat its rash.
In spite of its name, it’s not actually an oak. It does play an ecological role, providing food for many birds and small mammals, as well as deer and insect larvae. It also helps to anchor slopes and prevent erosion. And it’s a pioneer species, meaning it is one of the first plants to return after a disturbance like a wildfire. Since climate change is leading to more and more wildfires, we can expect to see more poison oak in the future.
Photo courtesy of Neill Fogarty.