43 



described by Pfister et al- (1977). Associated 

 species occurring at one or more sites with C. 

 subniveum include: Artemisia tridentata (big 

 sagebrush), Artemisia f rigida (fringed sagewort) , 

 Aqropyron spicatum (bluebunch wheatgrass) , 

 Chaenactis douglasii (hoary chaenactis) , Penstemon 

 cyaneus (dark-blue penstemon) , and Penstemon 

 deustus (hot-rock penstemon) . 



In Utah, this species occurs in pinyon-juniper 

 communities. 



2. TOPOGRAPHY: The Montana populations occur 

 primarily on southeast-facing slopes, at ca. 6800 

 (2040 m) to 8500 ft (2550 m) in elevation. In 

 Utah, the species occurs near 6300 ft (1890 m) in 

 elevation (Welsh et al. 1987) . 



3. SOIL RELATIONSHIPS: The French Creek population 

 occurs in well drained, gravelly to cobbly soils 

 derived from parent material of Devonian or 

 Cambrian origin (Alt and Hyndman 1980) . The Elk 

 Lake (002) population also occurs on unstable 

 gravel and rockslides. 



4. REGIONAL CLIMATE: Cirsium subniveum occurs in a 

 region of Montana that has very dry, continental 

 climate conditions. Much of the yearly 

 precipitation falls as rain or wet snow in May and 

 June, with large convective storms providing the 

 mid- and late summer moisture. Winters are cold 

 and dry, with precipitation occurring mostly in 

 the form of snow. The following data (Table 1) 

 come from long term (1951-1980) climatological 

 stations (U.S. Department of Commerce 1982). The 

 nearest long term climatological station to the 

 Laurin Canyon (001) C. subniveum population is at 

 Virginia City. The station is approximately 13 

 miles east and 2,800 ft (840 m) lower than the 

 Laurin Canyon (001) population. The nearest long 

 term climatological station to the Elk Lake (002) 

 population is at Lake View. This station is 

 approximately 8 miles northeast, and 90 ft (27 m) 

 higher than the Elk Lake (001) population. 

 Finally, the nearest long term climatological 

 station to the French Creek (003) C. subniveum 

 population is at Dillon. The station is 

 approximately 11 miles southeast, and 1,900 ft 

 (570 m) lower then the French Creek (003) 

 population. 



