12 



Phacelia hastata (whiteleaf phacelia) 



primrose) 

 Stipa comata (needle and thread grass) 

 Tetradymia canescens (gray horsebrush) 



2 . TOPOGRAPHY AND SOILS : Astragalus ceramicus var . apus 

 is found on sandy well-drained soils in blowouts 

 associated with sand dune areas. Individuals are 

 located on open south and west facing slopes, at 6600 

 ft. elevation. The slopes are moderately steep (2 0- 

 30%) . 



F. POPULATION DEMOGRAPHY AND BIOLOGY 



1. POPULATION SIZE AND CONDITION: Astragalus ceramicus 

 var. apus was reported in 1987 to have a well 

 established large population (Schassberger , 1987) . 

 However, I noted that there were few individuals (less 

 than 100) and no large populations. I did not make an 

 intensive survey of the area to confirm the decrease 

 of individuals. There is no evidence to indicate that 

 this taxon can go dormant over entire growing seasons, 

 so these preliminary observations are taken to 

 indicate a major population decline. 



G. REPRODUCTIVE BIOLOGY: Astragalus ceramicus var. apus 

 is a perennial that reproduces by seed. 



H. LAND OWNERSHIP: Astragalus ceramicus var. apus occurs on 

 BLM and private lands. 



II. ASSESSMENT AND MANAGEMENT RECOMMENDATIONS 



A. THREATS TO KNOWN POPULATIONS: Astragalus ceramicus var. 

 apus occurs on the sand dune region in the Centennial 

 Valley where there is light to moderate grazing pressure. 

 In 1987 the populations were reported as thriving. 

 However, in 1993 during the sensitive plant survey I 

 observed only a few small populations. A possible 

 factor is the livestock use in the area, as suggested by 

 Schassberger (1988) . 



B. FURTHER ASSESSMENT AND MANAGEMENT NEEDS: The decline in 

 numbers warrants a study to determine the cause before 

 future management decisions can be made. 



C. SUMMARY: Astragalus ceramicus var. apus occurs in Montana 

 in the sandy hills and plains of the Centennial Valley. 

 The apparent population decline is a priority for 

 sensitive species monitoring on lands administered by BLM 

 and U.S. Fish and Wildlife Service. It is among the 

 singular features of the Centennial Sandhills, an area 

 which has been proposed for natural area recognition 

 (Lesica, no date) . 



