The San Diego Natural History Museum Department of Botany focuses on biodiversity, evolutionary history research, and documentation of the flora in Southern California, Baja California, and adjacent areas. With a collection dating back to the 1870s, the SD Herbarium is invaluable as a scientific resource that documents regional plant populations and has been used for basic natural history research. Botanists with regional colleges, universities, and museums utilize the collections for their own research and for student projects, both by visiting the collection in person and/or through loans. The SD Herbarium houses over 270,000 accessioned specimens, all of which have been databased. Specimens from southern California account for nearly half of our collection and about 20% of our collection is from Baja California. Nearly all San Diego County and Baja California records have been georeferenced (99%). The Botany Department maintains two web sites that serve researchers with searching and mapping pages, checklists, voucher images, data input forms for collectors, and other tools for using our collections. SDPlantAtlas.org serves researchers interested in the plants of California’s San Diego and Imperial Counties. BajaFlora.org serves the needs of researchers interested in the plants of the two states of Baja, Mexico, consolidating the SD collections and the collections of the two primary herbaria in Baja.