Summary
Takhtajan and Cronquist treated the Californian Province of the Madrean Region in a more restricted sense than many plant geographers, restricting the province to the Great Central Valley, Central Western California, and Southwestern California, as well as the northern portion of Baja California (Cronquist 1982). Essentially this is an area with a Mediterranean climate and little or no severe frost. Excluded from this Province are Northwestern California, the Sierra Nevada Mountains, and the Cascade Mountains, which are instead grouped with the Vancouverian Province of the Rocky Mountain Region due to higher annual precipitation and lower temperatures in winter and/or summer. These additional regions are often included within a broader “California Floristic Province” (CFP, see references).
Major vegetation types within the Californian Province include Grassland, Oak Savanna and Woodland, Chaparral, Sage Scrub, and Mixed Coniferous-Broadleaf Evergreen Forest. Riparian and Floodplain vegetation is typically dominated by deciduous trees, and Coniferous Forest occurs in some higher elevation and coastal sites. Fire is an important ecological factor in vegetative succession as well as the life history of many native vascular plant species. Edaphic factors, particularly serpentinite and other ultramafic bedrock types, are an important factor in speciation and endemism in the California flora. Both neo-endemics and paleo-endemics are well represented in the endemic flora.
The list of endemic vascular plant taxa presented here is based on the analysis of Burge et al. (2016), which utilized strict criteria for endemic status, and does not include near endemics. Taxa considered for endemic status in this analysis were restricted to those treated as valid taxa in the Jepson Manual, Second Edition (TJM2, Baldwin et al., 2012), as well as equivalent authorities in Baja California (O'Brien et al., in press; O'Brien and Rebman, in press) and Oregon (Oregon Flora Project, 2015). According to this analysis, there are 1163 endemic vascular plant species, subspecies, or varieties in the Californian Province.
Burge et al. (2016) lists 2612 vascular plant species, subspecies, or varieties that are strict endemics to the broadly circumscribed CFP. A substantial number of the narrowly distributed species in the northern portions of the CFP will be listed here as endemic to the Vancouverian Province.
Only 13 genera are endemic (marked red) and no families are endemic. A much larger number of genera are endemic to the State of California, or a more broadly circumscribed CFP. For example, the genus Sequoia is distributed from the central California coast to southwest Oregon, and is endemic to the broader CFP, but in the Takhtajan and Cronquist system, Sequoia occurs in both the Californian and Vancouverian Provinces.
This list is based on data from the following paper:
Burge, D.O., J.H. Thorne, S.P. Harrison, B.C. O'Brien, J.P. Rebman, J.R. Shevock, E.R. Alverson, L.K. Hardison, J. Delgadillo RodrÍguez, S.A. Junak, T.A. Oberbauer, H.Riemann, S.E. Vanderplank & T. Barry. 2016. Plant Diversity and Endemism in the California Floristic Province. Madrono 63 (2):3–206.
References
Baldwin, B., D. Goldman, D. Keil, R. Patterson, T. Rosatti, & D. Wilken, (eds.). 2012. The Jepson Manual: Vascular Plants of California, second edition. University of California Press, Berkeley, CA.
Cronquist, A. 1982. Map of the Floristic Provinces of North America. Brittonia 34:144–145.
Lewis, H. 1972. The origin of endemics in the Californian flora. In: Taxonomy, Phytogeography and Evolution. Ed. D. H. Valentine. Academic Press.
O'Brien, B., J. Delagdillo-Rodriguez, S. Junak, T. Oberbauer, J. Rebman, H. Riemann, & S. Vanderplank. In Press. The rare, endangered, and endemic plants of the California Floristic Province portion of Baja California, Mexico. Aliso.
O'Brien, B. & J. Rebman, with J. Delagdillo-Rodriguez, S. Junak, T. Oberbauer, H. Riemann, & S. Vanderplank. In Press. A checklist of the California Floristic Province portion of Baja California, Mexico. Aliso.
Oregon Flora Project. 2015. Website http://www.oregonflora.org (accessed 31 January, 2015).
Qian, H. 1999. Floristic analysis of vascular plant genera of North America north of Mexico: characterization and phytogeography. Journal of Biogeography, 26: 1307-1321.
Raven, P. H. & Axelrod, D. I. 1978. Origin and Relationships of the California Flora. University of California Press, California.
Stebbins, G. L. & Major, J. 1960. Endemism and speciation in the Californian flora. Ecological Monographs. 35: 1-35.