Whether lounging in your backyard, out on the hiking trail, or exploring the backcountry, you’ve probably come across an oak tree. These magnificent plants have played key roles in the health of California’s ecosystems for millions of years and remain just as vital today.

I find myself repeatedly impressed by the resilience of oaks, so much so that I created this field guide to learn more about them and share that knowledge with others. My hope is that this guide can inspire curiosity about oak trees, get people looking at them a little more closely, and provide the tools to identify them on their own.

This guide is always changing and (hopefully) improving as I dive deeper into researching oaks. It’s possible that I will upload edited versions, in which case the edits and additions will be listed below. Feedback and suggestions are always welcome!