California False Bindweed, California Morning Glory, Coastal Morning Glory. Found along roadsides, hillsides, trails, just about everywhere in the front country (I have not noticed it in the back country where C. purpurata seems to take over).
Large white flowers, sometimes with pink stripes.
Blooms all year, but is at its peak around May.
Seen blooming above 2000ft (which is odd as the subspecies which are supposed to live here don’t go that high).
May be distinguished from C. purpurata by the bracts at the base of the flower. In this species the bracts surround, and mostly obscure, the calyx (the sepals at the base of the flower), while in C. purpurata the bracts look like tiny little leaves a few millimeters below the flower.