61 



mancwn, and Erigeron caespitosus. Finally, the low sagebrush grassland of the Sage Creek Study Area 

 was relatively extensive, made up oi Artemisia arbitscula /Festuca idahoemis h.t. at ca. 6,600 ft.; 

 common associated species include Chrysothammis viscidiflorus, Antennaria micvophylla, Agropyron 

 spicatum, and Phlox hoodii. These settings in both study areas are arid, alkaline, and have low 

 vegetation competition. 



POPULATION INFORMATION: Population numbers range from 50 to 300 in most populations, but 

 the Bannack area population approaches 10,000. It appears to be centered on the State Park 

 (Vanderhorst 1995). The largest kno\\ai population of the species is in Horse Prairie (Vanderhorst 

 1995). Numbers can be difficult to estimate because the species fomis mats or aggregates that camiot be 

 distinguished as individuals. 



MANAGEMENT CONSIDERATIONS: Sphaeromeria argentea is a low, aromatic subslmib that did 

 not show signs of being grazed. Some of its habitat settings are within primary range, as at the Emiont 

 Gulch site, where the affect of trampling alters the substrate. Grazing, mining, and other activities 

 sometimes promote the spread of exotic species and pose indirect management concerns. Mining 

 activity is a potential threat to the species in its limestone outcrop habitat. Invasion by exotic species has 

 not occurred in the study area sites, but potentially includes Bromus tectorum, Centaurea maculosa, and 

 Meli lotus spp. 



This species is recommended for BLM Watch status because of the generally low population numbers, 

 restricted range, and widespread (though low) levels of existing threats. 



