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feet on the east slopes of the Beartooth Mountains and 

 7,200-7,800 feet in the Pryor Mountains. In Wyoming, 

 Shoshonea occurs at elevations of 5,800-9,000 feet (Evert 

 and Constance 19821 Mollis Marriott, Wyoming Natural 

 Heritage Program, pers. comm.). The species is found in 

 mountainous terrain in areas of sharp relief. In Montana, 

 Shoshonea generally occurs on level or gently sloping 

 ridgetops, or on the shoulders of ridges. It is 

 occasaionaly found on steeper slopes with a warm aspect. 

 These habitats are very exposed to strong winds, and winter 

 snow accumulation is assumed to be minimal. 



In Montana, Shoshonea is found at the north end of the Big 

 Horn Basin in the drainages of the Big Horn River and the 

 Clarks Fork of the Yellowstone River. 



5. Edaphic factors: Shoshonea pulvinata occurs in poorly 

 developed soils derived from limestone and dolomite. 

 Although analyses were not conducted, soils are probably 

 highly calcareous. Veseth and Montagne (1980, p. 38) 

 describe similar shallow soils derived from Madison 

 Limestone in the Big Snowy Mountains of northcentral 

 Montana. These soils are well drained, with moderately 

 rapid runoff and moderate permeability. Soil cores have ^5- 

 90X limestone cobbles and pebbles, and a fine fraction high 

 in silt. These soils are slightly sticky and plastic when 

 wet, friable to very friable when moist, and slightly hard 

 when dry. The high stone and silt content may help retain 

 moisture during the growing season. These higher elevation 

 azonal soils have not been classified by the Soil 

 Conservation Service. 



6. Dependence of this taxon on natural disturbance: Shoshonea 

 appears to be confined to areas where exposure to the wind 

 minimizes snow accumulation, and where subsequent soil and 

 vegetation development are thus inhibited. Without the 

 effects of wind, soils would presumably mature, and zonal 

 vegetation (i.e., Douglas fir forest) could develop and 

 shade out individuals of Shoshonea . 



7. Other unusual physical features: None observed. 



C. Biological characteristics. 



1. Vegetation physiognomy and community structure: In Montana, 

 Shoshonea pulvinata occurs in relatively barren, fellfield- 

 like communities amidst dry forests of Douglas fir and 

 limber pine. In these communities, scattered, small 

 individuals of these tree species, as well as shrubby 

 cinquefoil ( Potentilla fruticosa ) and Wyoming ninebark 

 ( Phvsocarpus monoqynus ) , may also be present. Otherwise, 

 the vegetation is dominated by herbaceous perennials, 

 including graminoids such as spike fescue ( Hesperochloa 

 k i nq i i ) and curly sedge ( Carex rupestris ) , and cushion- 



