SOZA, VALERIE L. 1*, STEVE BOYD1, AND ANDREW C. SANDERS2. 1Herbarium, Rancho Santa Ana Botanic Garden, Claremont, CA 91711, and 2Herbarium, Department of Botany and Plant Sciences, University of California, Riverside, CA 92521. - Phytogeographic “black holes” in southern California botany, a geographic information systems (GIS) model based on herbarium collections of two representative genera, Camissonia and Salvia.
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