U.C. Cooperative Extension: Links to UC Cooperative Extension county offices and regional resources plus online information on many horticultural topics.
U.C. Berkeley Botanical Garden Sick Plant Clinic
200 Centennial Drive, Berkeley
First Saturday morning of each month.
Helen Crocker Russell Library of Horticulture
Strybing Arboretum, Ninth Ave. at Lincoln Way, Golden Gate Park, S.F.
(415) 661-1316 ext.303
California Native Plants Discussion Group
Listserve for people with questions about California native plants.