2006). We imported all statewide layers into Arc GIS 9.1 (ESRI 2005) for more detailed analysis. Each data layer was reclassified with Spatial Analyst to create CH5424802 cost new layers with a binary code indicating presence or absence of the taxon in each 1 km2 raster cell in California. A mask layer for Napa County was created by reclassifying our layer for the State of California to create a new layer with a binary code distinguishing Napa from the rest of the state. We multiplied the statewide distribution layers for individual taxa with the Napa County mask layer to create new layers isolating plant distributions within Napa County (cells with a product of one). We queried the attribute tables in the resulting layers and then classified

those taxa with distributions meeting the minimum area of occupancy criteria for local rarity (<250 km2) into one of the three threat categories (L1, L2, L3) or the LH category. Results Our results indicated that 89 taxa from 34 families met the area of occupancy criteria for local rarity ranks 1, 2, 3, and

H in Napa County, CA (Table 2). Figure 1 shows examples of the distributions of three L-ranked plants (categories 1, 2, and 3) based on analysis using 1 km2 grid cells. Although each of these taxa exhibits a relatively large distribution in California, they are all rare to some degree in Napa County. A post-hoc analysis of the distributions of the locally rare taxa identified in this study revealed that these plants are distributed in an average of 20 counties in see more California. Urease This indicates that they are relatively widespread in the state and would fail to meet criteria for conservation status at state or global levels but could be given status at the local level via the L-rank system. Table 2 Native locally rare plant taxa distributed in Napa County L-rank Taxon Family L1 Lomatium dasycarpum (Torr. & A. Gray) J.M. Coult. & Rose ssp. tomentosum (Benth.) Theob. Apiaceae L1 Silene lemmonii S. Watson Caryophyllaceae L1 Carex brainerdii Mack. Cyperaceae L1 Chimaphila menziesii (D. Don) Spreng. Ericaceae L1 Phacelia mutabilis Greene

Hydrophyllaceae L1 Calochortus venustus Benth. Liliaceae L1 Bromus grandis (Shear) Hitchc. Poaceae L1 Elymus glaucus Buckley ssp. jepsonii (Burtt Davy) Gould Poaceae L1 Ceanothus prostratus Benth. Rhamnaceae L2 Eryngium armatum (S. Watson) J.M. Coult. & Rose Apiaceae L2 Gnaphalium bicolor Bioletti Asteraceae L2 Gnaphalium canescens DC. ssp. microcephalum (Nutt.) Stebb. & D.J. Keil Asteraceae L2 Heterotheca sessiliflora (Nutt.) Shinn. ssp. bolanderi (A. Gray) Semple Asteraceae L2 Barbarea orthoceras Ledeb. Brassicaceae L2 Dudleya caespitosa (Haw.) Britton & Rose Crassulaceae L2 Juncus lesueurii Bol. Juncaceae L2 Juncus occidentalis (Coville) Wiegand Juncaceae L2 Juncus phaeocephalus Engelm. var. phaeocephalus Juncaceae L2 Forestiera pubescens Nutt. Oleaceae L2 Limonium californicum (Boiss.) A. Heller Plumbaginaceae L2 Ceanothus dentatus Torr. & A.