Aristolochia californica (California pipevine). I saw these in two separate areas along the Madrone Trail, on shady banks above the trail. I don't have a good way to identify the specific locations, but they were in the general area of the northernmost stream crossing - maybe ~1/2 mile either way. I really do need to get back here in late winter when they bloom ... with a gps.
2017AristolochiaAristolochiaceaePFSF Bay Area
From Las Trampas - April 29 2017