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PLANT DIVERSITY AND ENDEMISM IN THE CALIFORNIA FLORISTIC PROVINCE

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Abstract

The California Floristic Province (CFP) is an area of high biodiversity and endemism corresponding roughly to the portion of western North America having a Mediterranean-type climate. High levels of diversity and endemism in the CFP are attributed to the unique geo-climatic setting of the region. In recent years, much has been learned about the origins of plant diversity in western North America. This work, however, has been hindered by a focus on political rather than biotic regions, such that much more is known about diversity and endemism in the state of California than the natural biotic region represented by the CFP. Here we present a preliminary list of native land plants (vascular plants and bryophytes) found in the CFP, as well as an analysis of diversity and endemism patterns at the level of both species and minimum rank taxa (MRT; species and infraspecific taxa). A total of 6,927 MRT are native to the CFP, including 6,143 vascular plants and 784 bryophytes. Of these, 2,612 vascular plants are endemic to the CFP (42%) compared to 37 endemic bryophytes (5%). Finally, 2,506 native CFP vascular plant MRT (41% of the CFP flora) and 454 CFP bryophyte MRT (58% of the CFP flora) are found outside California in the Oregon and Baja California parts of the CFP. This high degree of sharing across political boundaries among both vascular plants and bryophytes highlights the cohesiveness of the CFP, and the need to focus more research effort on biotic regions.
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... The other confirmed species for which new records from Mexico and the BCP are presented are P. octopunctatus, which has a widespread distribution, and the new records are near the limits of its known distribution, and P. adumbratus, which until now was recorded from the California floristic province, an area of high endemism [37,38] located along the coast of the North American Pacific. In this study, P. adumbratus is newly recorded for Mexico, as well as from a new ecoregion, namely, Baja California's Central Desert ecoregion, as defined by Gonzalez-Abraham et al. [1]. ...
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