MADRONÄ O, Vol. 52, No. 4, pp. 222±257, 2005 SERPENTINE ENDEMISM IN THE CALIFORNIA FLORA: A DATABASE OF SERPENTINE AFFINITY H. D. SAFFORD1,2,J.H.VIERS3, AND S. P. HARRISON2 1 USDA-Forest Service, Paci®c Southwest Region, 1323 Club Drive, Vallejo, CA 94592
[email protected] 2 Department of Environmental Science and Policy, University of California, Davis, CA 95616 3 Information Center for the Environment, DESP, University of California, Davis, CA 95616 ABSTRACT We present a summary of a database documenting levels of af®nity to ultrama®c (``serpentine'') sub- strates for taxa in the California ¯ora, USA. We constructed our database through an extensive literature search, expert opinion, ®eld observations, and intensive use of accession records at key herbaria. We developed a semi-quantitative methodology for determining levels of serpentine af®nity (strictly endemic, broadly endemic, strong ``indicator'', etc.) in the California ¯ora. In this contribution, we provide a list of taxa having high af®nity to ultrama®c/serpentine substrates in California, and present information on rarity, geographic distribution, taxonomy, and lifeform. Of species endemic to California, 12.5% are restricted to ultrama®c substrates. Most of these taxa come from a half-dozen plant families, and from only one or two genera within each family. The North Coast and Klamath Ranges support more serpentine endemics than the rest of the State combined. 15% of all plant taxa listed as threatened or endangered in California show some degree of association with ultrama®c substrates. Information in our database should prove valuable to efforts in ecology, ¯oristics, biosystematics, conservation, and land management.