USDA Plants Database: A database providing distribution maps and detailed information on native and non-native plants
Calphotos a photo data base of California plants: http://calphotos.berkeley.edu/flora/
California Native Plant Society (CNPS) has many local chapters whose volunteers may be able to help you identify a plant you found growing in the wild.
California Native Plant Society Facebook Group provides help with California plant identification.
Calflora Information on wild California plants. Calflora Plant ID Help
Jepson Online Interchange for California Floristics Index to California plant names. The revised version of the Jepson Manual online. It will be updated on a regular basis: http://ucjeps.berkeley.edu/eflora/
California Consortium of Herbaria serves as a gateway to information from California vascular plant specimens that are housed in participant herbaria.
CA Native Grassland Association, How to Key a Grass, anatomy of grass, plantID.net, definitions, etc..
Field Guide for Common California Rangeland and Pasture Plants of California. 2016. Authors: Larry Forero, Josh Davy, Sheila Barry, James Bartolome, and Stephanie Larson.
CalPhotos: Fungihis form accesses images of fungi
U.S. Wildflowers Family List for California
Ojai Valley Conservatory: CA Native Flowering Plants & Wildflowers
Urban Bee Gardens: A resource for planning a pollinator friendly garden. Hosted by UC Berkeley
Xerces Society: A resource for information on pollinator conservation. Includes pollinator-friendly plant lists and handy fact sheets and brochures
BugGuide A volunteer-run resource that allows registered users to upload photos of a North American insects for identification
UC Berkeley BioKeys A simple key for identifying an insect to order.
Common Spiders in California A page of photos and text maintained by UC Berkeley grad student Steve Lew.