Spotted in Willow Creek Park - Coleman Valley Road side.
A large climbing vine, one of 3 growth varieties I find, carpet like ground cover, climbing vines, or free standing multi trunked bushes.
Notice the adventitious roots between the poison oak vine and the tree trunk, in the second photo.
New leaves just beginning to show on poison oak plant.
Leaves out for about two weeks on the shaded north slope of oak woodland