Our knowledge of plant distribution remains forever incomplete. New species are discovered and described, range extensions are documented for known taxa, and geographical areas remain to be explored and catalogued. This phenomenon holds particularly true in California; with approximately 6300 described taxa, it is home to about ¼ of all plant species found in the United States and Canada. Yet many physiographic areas in California remain virtual “black holes” in botanical exploration, areas that have received little or no attention by botanical collectors. Attention to these areas is critical in the face of growing urbanization and other anthropogenic change, especially, within southern California. Despite publication of various floras and checklists for areas throughout southern California, the flora is not entirely known and a general decline in collecting activity and academic interest in floristic botanical issues has occurred. In an attempt to identify potential phytogeographic “black holes” in southern California, historical and recent collections of two representative genera were databased and mapped into a Geographic Information Systems (GIS) using ArcView. Camissonia and Salvia were selected as model taxa because they are widely distributed, generally common, and frequently collected. Taxon name, locality, collection date, collector and collection number, and latitude/longitude coordinates were recorded for herbarium specimens from several institutions in California, primarily Rancho Santa Ana Botanic Garden. Latitude and longitude coordinates in most cases were extrapolated from locality information given on specimen labels, using topographic maps. For this project, southern California was defined as including the ten counties from Santa Barbara, Kern, and Inyo southward. Useful information displayed in the GIS product included overall collection intensity within southern California and within specific geographical areas, collection intensity by dates, distribution of specific taxa, and collection activity by various collectors. Key regions of southern California warranting floristic attention were identified.

Key words: Camissonia, floristics, geographic information systems (GIS), herbarium collections, Salvia, southern California