In Utah, this species occurs in pinyon-juniper 

 communities (Welsh 1987) . 



2. TOPOGRAPHY: The Montana populations occur on all 

 aspects, but are more often found on the warmer 

 (east, south, west) aspects. Populations in 

 Montana occur at elevations that range from ca. 

 6100 (1850 m) to 8500 ft (2550 m) . In Utah, the 

 species occurs near 6300 ft (1890 m) in elevation 

 (Welsh et al. 1987), while in Wyoming it occurs 

 from 6160 ft. (1880 m) to 6850 ft. (2100 m) in 

 elevation (Gardner 1974) . 



3. SOIL RELATIONSHIPS: The French Creek population 

 occurs in well drained, gravelly to cobbled soils 

 derived from parent material of Devonian or 

 Cambrian origin (Alt and Hyndman 1980) . The Elk 

 Lake ( (002) , (006) , (007) ) , Hidden Lake (008) and 

 West Fork Madison (004) populations occur on 

 unstable gravel and rock slides derived from 

 Huckleberry Ridge Tuff (Sonderegger et al. 1982) . 

 The Big Sheep Creek (005) population occurs on 

 talus and gravels derived from the Madison group, 

 Mission and Lodgepole limestone formations 

 (Scholten et al . 1955) . This information 

 indicates that the distribution of Cirsium 

 subniveum appears to be related to unstable rock 

 and gravel slides, but it does not appear to be 

 tied to a particular geologic parent material. 



4. REGIONAL CLIMATE: Cirsium subniveum occurs in a 

 region of Montana that has a very dry, continental 

 climate. Much of the yearly precipitation falls 

 as rain or wet snow in May and June, with large 

 convective storms providing mid- and late summer 

 moisture. Winters are cold and dry, with 

 precipitation occurring mostly in the form of 

 snow. The following data (Table 1, p. 9) come 

 from long term (1951-1980) climatological stations 

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

 long term climatological station to C. subniveum 

 populations on the east edge of the Ruby Mountain, 

 and the south edge of the Tobacco Root Mountains 

 is at Virginia City (elev. 5776 ft. (1760 m) ) . 

 The station is approximately 13 miles east and 

 1025 ft (312 m) lower than the Laurin Canyon (001) 

 population, and approximately 14 miles south and 

 1000-2000 ft. (300-600 m) lower than the Mill 

 Creek (011, 012) and Stonewall Creek (009) 

 populations. The nearest long term climatological 

 station to the Gravelly Range populations is at 

 Lake View (elev. 6710 ft. (2045 m) . This station 



