Vascular Plants of the Whipple Mountains

Abstract

The Sonoran and Mojave deserts meet just north of the Whipple Mountains, which are situated in southeast San Bernardino County, California, along the Colorado River and adjacent to Arizona. Vegetation from the Pleistocene to the present was inferred from previously published packrat midden data and the current floristic composition. Climate data suggest that summer rainfall is a factor underlying the vegetational differences between the western and eastern portions of the Sonoran desert. Plant collections in the area yielded primarily California Sonoran plants, but also several Mojave and Arizona Sonoran plants. A fair number of the Arizona Sonoran plants collected were on the western margins of their ranges. Three species new to California's flora were documented in this study: Berberis harrisoniana, Delphinium scaposum, and Erigeron oxyphyllus.