We update and revise the serpentine affinity database of Safford et al. (2005), which documents levels of plant taxon association with ultramafic (“serpentine”) substrates in the California flora. The revised database reflects recent taxonomic changes consistent with the second edition of the Jepson Manual (TJM2) and more recent updates to the Jepson eFlora, and includes additional species that were not previously documented as serpentine associates. We also include serpentine-associated species that have been described since the publication of TJM2 and are not yet incorporated in the eFlora. A number of taxa were removed from the Safford et al. (2005) database due to new ecological information or taxonomic changes. As before, the new database presents information on rarity, geographic distribution, taxonomy, and lifeform. Based on our new database numbers and TJM2's list of California endemic species, the percentage of California endemic full species that are +/– restricted to ultramafic substrates has risen to 14.7%. Of 255 total endemic taxa in our database (including strict and “broad” endemics), 148 (c. 60%) come from only ten plant families, concentrated mostly in one or two genera per family. The North Coast and Klamath Ranges continue to support more serpentine endemics than the rest of the State combined. The previous version of the database has been widely used in biodiversity research and conservation management, and we hope that this improved and updated version will prove as valuable.