The Oak Compendium is a comprehensive database of oak species from around the world, providing botanists, naturalists, and oak enthusiasts with detailed information about the amazing genus Quercus.

Why This Site?

Almost everyone knows what an oak is, and many can even point to one in the wild. But getting them to species can be a huge challenge that stumps even the most seasoned botanist—just start looking at herbarium records to see all of the misidentified material! After years of frustration with the lack of a comprehensive oak identification resource, the Oak Compendium was born.

The goal is to gather and organize information to provide the ultimate guide to oak identification.

About the Author

My name is Jeff Clark and I love going out and wandering in nature and celebrating how little I know and how much there is to learn. I know a little about a lot and a good amount about oak galls and oaks. I am a bit of a fanatic about plant galls—so much so that I built Gallformers, a website dedicated to helping catalog and identify them (source on GitHub). If it were not for iNaturalist, the conjunction of people and events to make this possible likely would never have occurred.

When it comes to plant galls, I learned that I had to be knowledgeable about the host plants as well. I also quickly learned that the coolest galls are on oaks, and that oaks are hard to identify to species. So I figured: why not try to become an expert at oak identification? I have been working on this for the past five years and have gotten moderately good at it. I hope one day to take all that I have learned and to write a Field Guide to Oaks.

Database Statistics

Data Sources

The taxonomic structure used in this compendium follows iNaturalist, which provides the authoritative hierarchy of subgenera, sections, and species.

The primary species data—descriptions, identification notes, and range information—comes from my own research and field observations. Oaks of the World serves as an important secondary source, providing additional morphological details and distribution data.

Conservation status data is sourced from the IUCN Red List of Threatened Species, retrieved via the IUCN Red List API. Citation: IUCN 2024. IUCN Red List of Threatened Species. Version 2024-2 <www.iucnredlist.org>.

Other sources have been consulted as well; these are credited on each species page where applicable.

Data Licensing

Species Data: All Rights Reserved unless otherwise stated.

The data incorporates information from multiple sources; see the individual species entries for source attributions.

Open Source

This project is open source. View the code, report issues, or contribute on GitHub.

Source Code: MIT License

API

The Oak Compendium provides a public REST API for programmatic access to species data. Read operations are open to all; write operations require authentication.