Berberidaceae: Barberry Family
The Barberry family of course, includes the eponymous barberries (closely related to the cultivated Mahonias). It also includes (for reasons that will be clear only to professional botanists) the entirely different Inside-out Flower or Redwood Ivy. Barberries can be tricky to identify with certainty. Jepson’s Barberry appears to be confined to the southeastern part of the county whereas the California Barberry is more common on the Peninsula but, there are plants found on the Peninsula that in many respects key out much more easily (but not completely) to Jepson’s Barberry so one needs to be cautious about one’s identification.