calcareous upland grassland, on both south-facing slopes with 

 Andropoaon scoparius , Artemisia 



cana and Rhus trilobata ; as well as on slopes with Stipa 

 comata and Juniperus horizontalis . The list of associated 

 species includes: 



Andropogon scoparius 

 Artemisia cana 

 Carex filifolia 

 Juniperus horizontalis 

 Mentzelia dispersa 

 Phacelia hastata 

 Senecio canus 

 Stipa comata 



2. Topography: Steep slopes at or near butte perimeter, most 

 often found on exposed southwest aspect. 



3. Soil relationships: Soil textures include mostly cobbles 

 and silts, from calcareous parent material. They have good 

 water-retaining capacity in spite of the exposed setting. 



E. Population biology and biological interactions 



1. Population size and condition: The Government Hill 

 population and subpopulations includes several hundred plants. 

 The new subpopulations found during 1994 fieldwork north of 

 Government Hill appear to be waifs downwind from the core 

 population. 



2. Reproduction: Outcrossing. 



3. Competition: This species does not occur in the 

 surrounding prairie communities in which competition for water 

 and light are high compared to its sparsely-vegetated habitat. 

 The south flank of Slim Buttes also has potential habitat but 

 is heavily invaded by yellow sweet clover ( Melilotus 

 officinalis ) , which alters the course of succession in its 

 nitrogen-fixing capacity, out-competing many early-succession 

 species. 



4. Herbivory: There is infrequent browsing; two 

 inflorescences had been almost completely browsed off. 



F. Assessment and management recommendations: This species is 

 not recommended for further consideration by the U.S. Forest 

 Service because of few threats, and its presence in distant units 

 of the District on both sides of the state line. 



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