22 



have been found on granitic soils, as well as 

 limestone and other sedimentary substrates. 



6. Dependence of this taxon on natural 

 disturbance: It appears that P. lemhiensis has 

 some degree of adaptation to natural 

 disturbance, as evidenced by its ecological 

 preference for more open microhabitats, i.e., 

 rock outcrop areas and steep rocky slopes with 

 some natural soil slippage. 



7. Other unusual physical features: None 

 observed. 



C. Biological characteristics. 



1. Vegetation physiognomy and community structure: 

 In Montana, P. lemhiensis is associated with 

 a.) sagebrush-bunchgrass steppe, b.) savanna- 

 like pine-shrub communities, c.) temperate 

 evergreen conifer forests dominated by trees 

 with more or less conical crowns, and d.) 

 ecotones between the steppe and conifer forest 

 types. 



2. Regional vegetation types: Penstemon 

 lemhiensis occurs in four climax vegetation 

 types as mapped by Ross and Hunter (1976): a.) 

 Subalpine fir/Douglas-fir/Ponderosa Pine climax 

 forest, b.) Subalpine fir/Douglas-fir climax 

 forest, c.) Silty Range site, 10-14" 

 precipitation zone, with bluebunch wheatgrass, 

 prairie junegrass, etc., and d.) Silty Range 

 site, 15-19" precipitation zone, with Idaho 

 fescue, bluebunch wheatgrass, etc. The range 

 of the species lies largely within the Douglas- 

 fir Forest Section of the Rocky Mountain Forest 

 Province, with a minor portion in the Cedar- 

 Hemlock-Douglas-f ir Forest Section of the 

 Columbia Forest Province, as mapped by Bailey 

 (1976) . 



3. Frequently associated species: In Beaverhead 

 County, Montana, Penstemon lemhiensis generally 

 occurs in areas below or near the lower tree 

 line of forests dominated by Pseudotsuga 

 menziesii and/or Pinus contorta . The 

 associated vegetation is most often dominated 

 by Artemisia tridentata and bunchgrasses, 

 including Agropyron spicatum and Festuca 

 idahoensis. Other native plant species 

 associated with P. lemhiensis at one or more 

 locations include: 



