79 



HABITAT: Stephwwmeria spuiosa occupies arid grasslands on stony loam at low elevations from ca. 

 5000-6400 ft (Appendix D-8). The Upper Madison Valley study area may resemble the historic 

 Centennial Valley collection site in that both have substrate derived fi-om coarse alluvium. 



The grassland setting is predominantly Agropyron spicatum h.t., but Stipa comata, Festuca 

 idahoensis, Bouteloua gracilis, and ground cover of Selaginella densa are locally co-dominant or 

 abundant. 



Associated species include the following: 



Agropyron spicatum 

 Antennaria microphylla 

 Artemisia frigida 

 Astragalus adsurgens 

 Astragalus terminal is 

 Bouteloua gracilis 

 Br emus tectorum 

 Chrysopsis villosa 

 Festuca idahonis 

 Gutierrezia sarothrae 

 Koeleria macrantha 

 Musineon divaricatum 

 Oxytropis sericea 

 Phlox hoodii 

 Poa secunda 

 Selaginella densa 

 Senecio canus 

 Stipa comata 



POPULATION INFORMATION: Population numbers in the study area range from 60 to an 

 "extensive" population that is thought to contain more than 200 plants. These populations represent the 

 largest knovvTi numbers for the species in Montana. The tliree other historic collections described the 

 species as "rare" or did not describe its frequency at all. 



The species reproduces strictly by seed and is likely to flower during most years because it is drought- 

 tolerant. 



MANAGEMENT CONSIDERATIONS: The Dillon Resource Area harbors the only known extant 

 occurrences of this species in Montana, with possible extension onto the Wall Creek WMA. We have 

 no evidence to indicate that it is affected negatively or positively by livestock management practices. 

 The geographic restriction of the species and the encroacliment of knapweed upon its habitat provides 

 the basis for considering its designation as a BLM watch species. 



