15 



Haplopappus armerioides . . (thrifty goldenweed) 

 Hymenopappus f il if ol ius . . (Columbia cut-leaf) 



Koeleria macrantha (prairie junegrass) 



Linum perenne (blue flax) 



Musineon divaricatum (Leafy musineon) 



Opuntia polycantha (plains pricklypear) 



Oxytropis sericea (white locoweed) 



Phlox hoodii (Hood ' s phlox) 



Phlox alyssifolia ( Alyssum-leaved phlox) 



Poa secunda (Sandberg's bluegrass) 



Yucca qlauca (soapwell) 



Ziqadenus venenosus (meadow death-camus) 



TOPOGRAPHY: In Montana, populations of A. barrii 

 are most often found on eroding knolls, buttes, 

 and barren hilltops of a particular limestone 

 caprock. These sites range from level areas to 

 steep slopes (0-35%). Most sites occur on slopes 

 of intermediate steepness (3-8%). All slope 

 aspects are represented; however, many of the 

 sites in Montana are on north or northeast-facing 

 slopes . 



The recently verified sites in Montana range from 

 957 m (3,140 ft.) to 1,146 m (3,760 ft.) in 

 elevation. The historical site in Ekalaka may 

 have been located at approximately 1,128 m (3,700 

 ft.) in elevation (Ekalaka (006)). 



SOIL RELATIONSHIPS: Areas that often contain 

 Astragalus barrii have low vegetative cover, and 

 thus the soils are likely to be low in organic 

 matter. Within the White River drainage of South 

 Dakota, one population of Astragalus barrii was 

 found to be restricted to the Rockyford Ash Member 

 of the Sharps Formation (David Ode, S. Dakota 

 Natural Heritage Program, pers . comm.). From a 

 study of the Powder River populations in Wyoming 

 however, it was found to occur on eroding 

 sandstone bluffs (Roberts, 1977) . 



Sites surveyed in the Otter Creek and Tongue River 

 drainages in Montana, were often found to be high 

 in clays and silts, and low in sands. Many of 

 these sites were also sparsely stony. All of 

 these sites are on the Tongue River Member of the 

 Ft. Union Formation, which is represented by 

 yellowish-gray thick-bedded to massive calcareous 

 sandstone and siltstone, light-gray shaley 

 siltstone and shale, carbonaceous shale, numerous 

 coal beds, and reddish to lavender clinker 

 (Bergantino, 1980). See photographs pp. 59-61. 



