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37 



colonized disturbed areas where vegetative 

 cover is very low, i.e., roadbanks. In 

 most of these cases, a few individuals 

 have become established on roadcuts 

 adjacent to steep slopes supporting 

 undisturbed vegetation, but the majority 

 of the plants occur in the native habitat. 

 An exception was observed at the Big Hole 

 National Battlefield (006), where the 

 density of P. lemhiensis was much greater 

 on the roadcut along the old highway than 

 it was on the sagebrush slope above it 

 (Ramstetter 1983) . However, the majority 

 of the plants were still found on the 

 undisturbed slope above the road. 



3. Toxic and allelopathic interactions: None 

 known or observed. 



D. Hybridization. 



1. Naturally occurring: As discussed in 

 I.5.C., it has been hypothesized that P. 

 lemhiensis arose via hybridization between 

 P. cyaneus and P. speciosus . followed by 

 segregation and isolation (Keck 1940) . 

 Additional systematic studies are needed 

 to evaluate this theory. No evidence of 

 recent genetic interaction with other 

 species of Penstemon has been observed 

 during field studies in southwestern 

 Montana. 



2. Artificially induced: None known. 



3. Potential in cultivation: Unknown. 



E. Other factors of population ecology: The sparsely 

 scattered distribution pattern of the populations, 

 and their small average size, may have some 

 influence on the pollination biology. Smaller 

 populations that are more widely separated from the 

 others may be visited less frequently by effective 

 pollinators, thereby resulting in lower fruit and 

 seed production. Field studies are needed to test 

 this hypothesis. 



9. Current land ownership and management responsibility. 



A. General nature of ownership (Montana) : United 

 States Government, private. 



I 



