Figure 20. — Saabland 

 sagebrush (A. rigidaj 

 growing at the Snow 

 Field Station. The 

 ruler is ZO am long. 



Hybridization. --Both diploid (2n - 18) and tetraploid (2n = 36) forms of stiff 

 sagebrush are known (Ward 1953; McArthur and Plummer 1978). This species resembles 

 A. tripartita somewhat in its small size, silvery pubescence, and the deeply, narrowly 

 lobed leaves, but may be distinguished by the spikelike inflorescence, large leafy 

 bracts that subtend the heads, and the deciduous leaves. 



Distribution. --Stiff sagebrush occurs in dry rocky scablands in the Columbia and 

 Snake River basins and spills over into the northern end of the Great Basin. It grows 

 at elevations from 910 to 1,520 meters (3,000 to 5,000 feet) in Idaho, central and 

 eastern Oregon, and central and eastern Washington. It is adapted to the rocky scab- 

 lands of these States and fills an ecological niche similar to that of A. arbusaula 

 in the areas where it is found (Ward 1953) . 



Although several authors (Hall and Clements 1923; Davis 1952; Hitchcock and 

 others 1969) include western Montana in the distribution of stiff sagebrush, neither 

 Ward (1953) nor Beetle (1960) do. Wa^d (1953) claims the report of A. rigida from 

 western Montana is probably a result of errors in identification. He identifies the 

 specimens in this area as A. tripartita. 



Figure 21. — Leaves and 

 branches of saabland 

 sagebrush (A. rigida) . 



21 



