Since western poison oak (Toxicodendron diversilobum) typically loses its leaves in the Fall and doesn’t start leafing out again until after the first of the year, you might be surprised to know that it is coming out now, as I was (see photo taken today). Chalk it up to global warming, I suppose, but the result is that poison oak season is elongating — it’s starting earlier and likely ending later, although I don’t have evidence of it.

This is bad news for hikers, and the stewards who try to keep it cut back off the trail. But since I haven’t yet had a chance to get out there with clippers (perhaps tomorrow), be careful. I’ve seen a few sprouts right at the edge of the trail.

Part of what makes poison oak tough to spot is that it presents differently at different times of year and in different growing conditions. To see some of this variability, see this web site, which has a number of pictures of poison oak in various stages of its life and in different growing conditions. Also, poison oak will often vine up into bushes and small trees, blending in with the other vegetation, which makes it even harder to spot. I’ve often missed noticing poison oak in such situations, even when actively looking for it.

Our program of control is limited to keeping it about 3 feet off the trail, as since it is a native species we aren’t interested in eradicating it like we are invasive species such as Italian and Yellow Star thistle. So if you stay on the trail you should be safe, at least after I get out with the clippers, but it doesn’t hurt to be vigilant.