11 



in Montana has been surveyed. However, from 

 personal observation, there are still 

 unsurveyed areas that almost certainly support 

 populations. These include lands near Biddle, 

 south of the Ranch Creek 1 (024) site, and in 

 areas surrounding the Bell Creek (026) site. 

 Also, lands south of Ashland on the east side 

 of the Tongue River, and southwest of Ashland 

 on the west side of the Tongue River (on the 

 Northern Cheyenne Indian Reservation) may 

 harbor populations. 



5. Reports having cimbiguous or incomplete locality 

 information: 



a. Montana: See historical record cited 

 in (I.5.B.3.) , p. 7. 



6. Locations known or suspected to be erroneous 

 reports: 



a. Montana: None known. 



C. Biogeographical and phylogenetic history: 



Astragalus barrii is one of the few species with a 

 relatively restricted geographic range within the 

 Great Plains. Most of the species in the Great 

 Plains flora have extensive ranges, and many are on 

 the edge of their range within this area (Great 

 Plains Flora Association 1986) . 



The affinities of A. barrii with other members of 

 the Orophaca phalanx are clear; however, generic 

 delimitation remains disputed (Isely 1983, Barneby 

 1964) . * 



General environment and habitat description. 



A. Concise statement of general environment and 



habitat: In southeastern Montana, A. barrii is 

 restricted to heavy clay ("gumbo") knobs, buttes, 

 and barren hilltops. The calcareous clay soils in 

 which A. barrii occurs are likely to be low in 

 organic matter, as these locations are sparsely 

 vegetated. A very sparse cover of Pinus ponderosa 

 (ponderosa pine) or Juniperus scopulorum (Rocky 

 Mountain juniper) is found at some locations, but 

 often only a sparse shrub cover of Artemisia 

 tridentata (big sagebrush) and/or Atriplex 

 confertifolia (shadscale) is present. 



In southeastern Montana, summers are hot, with brief 



