> 



42 



species may be vulnerable to dramatic climatic 

 fluctuations such as the severe drought conditions 

 that prevailed in 1988. 



II. ASSESSMENT AND RECOMMENDATIONS 



12. General assessment of vigor, trends, and status: 

 Penstemon lemhiensis is a perennial plant species that is 

 currently known from 35 sites in Beaverhead and Ravalli 

 counties, Montana; it is also recently documented from 19 

 sites in Lemhi County, Idaho. In Montana, the average 

 population size is small (approximately 128 individuals) , 

 and the total number of plants observed to date is 

 approximately 4,420-4,525. While some populations appear 

 to be relatively stable, drastic declines have been 

 observed in three populations in Beaverhead County. 

 Impacts due to browsing by native animals and livestock, 

 and mining activities, have occurred in some populations; 

 weed control via herbicide application also represents a 

 current threat. The populations in Montana are very 

 sparsely scattered over an area of approximately 3,500 

 square miles, and there is much suitable habitat that is 

 apparently unoccupied. Although the species has 

 colonized disturbed habitats in some places, the plants 

 are never abundant in these situations, and this probably 

 represents an ephemeral response to sites that mimic its 

 native habitat. Owing to the low population numbers, the 

 widely dispersed distribution pattern, and the observed 

 declines in some areas, JP. lemhiensis should continue to 

 be closely monitored. Demographic monitoring transects 

 established in 1989 will provide data that can be used to 

 assess and predict population performance. 



13. Recommendations for listing or status change. 



A. Recommendation to U.S. Fish and Wildlife Service: 

 On the basis of current information summarized 

 herein, it is recommended that Penstemon lemhiensis 

 be retained in Category 2. In Montana, the average 

 population size is small, and the total number of 

 documented individuals is low. Observed declines in 

 several populations, and ongoing threats from mining 

 and browsing, dictate that the species be closely 

 monitored. Also, status surveys should be conducted 

 in Idaho; a detailed status recommendation could be 

 made upon completion of research in that portion of 

 the species' range. 



B. Recommendations to other U.S. federal agencies: 

 Penstemon lemhiensis has been placed on the lists of 

 sensitive species in Regions 1 and 4 of the U.S. 

 Forest Service. These designations should be 

 retained. In addition, £. lemhiensis should be 



