phacelia ( Phacelia hastata ) , big sagebrush ( Artemisia 

 tridentata ) , threetip sagebrush, ( Artemisia tripartita ) , Idaho 

 fescue ( Festuca idahoensis ) (DeVelice 1992) . 



Flora 



A recent floristic inventory of the Centennial Mountains on 

 BLM lands documented 362 taxa (including species, subspecies, and 

 varieties) representing 190 genera in 43 families (Lowry 1979) , 

 or approximately 15% of the flora of Montana (Shelley 1986) . 

 Dorn (1968) , in a more complete floristic study of the Red Rock 

 Lakes National Wildlife Refuge and adjacent Centennial Mountains, 

 listed 487 species in 243 genera and 65 families, or 

 approximately 21% of Montana's flora (Shelley 1986). Areas of 

 such high floristic and geographic diversity often harbor 

 numerous rare or unique species (Shelley 1986) . There are no 

 taxa known to be strictly endemic to the Centennial Region, 

 however a number of taxa occur there which are either regional 

 endemics or which occur on the edge of their range (Shelley 

 1986) . 



III. METHODS 



The Centennial Valley and Mountains was surveyed on May 26- 

 31, June 18-30, July 1-28, and August 3-20 for state plant 

 species of concern which have been documented from the Centennial 

 Valley (Table 1) . The search routes for each of the target 

 species were concentrated on BLM tracts with potential habitat, 

 as determined from review of existing records in the Biological 

 Conservation Database of the Montana Natural Heritage Program 

 (MTHP) . I reviewed specimens of target species at the Montana 

 State University (MSU) herbarium prior to the field season and 

 outlined potential new sites evaluating soil and aerial maps of 

 the study area. I conducted my surveys by hiking through each 

 target area, inspecting typical habitat as well as unusual 

 edaphic or topographic features. "Plant Species of Special 

 Concern" survey forms were filled out upon location of a target 

 plant (Appendix B) . Topographical maps were then marked with the 

 population and photographs of the individual species and their 

 habitat were taken. 



Identification of collections was made following Dorn (1984) 

 and Hitchcock and Cronquist (1973). More difficult 

 determinations were made by using specimens in the MSU Herbarium 

 for reference and consulting with Dr. J. Rumely. Voucher 

 specimens are deposited at MSU Herbarium. 



