Penstemon aridus (stiff-leaved penstemon) 



Phlox bryoides (moss phlox) 



Phlox lonqifolia (long-leaved phlox) 



Physaria qeyeri (Geyer's twinpod) 



Poa secunda (Sandberg's bluegrass) 



Sedum lanceolatum (lance-leaved stonecrop) 



Senecio canus (woolly groundsel) 



Taraxacum officinale (common dandelion) 



Tetradvmia canescens (gray horsebrush) 



Townsendia hookeri (Hooker's townsendia) 



Additionally, sites on private land. Bureau of 

 Land Management, and on State of Montana lands 

 have been invaded by weedy introduced species, 

 including Centaurea maculosa , Alyssum alyssoides . 

 and Bromus tectorum . 



TOPOGRAPHY: All known populations of Arabis 

 fecunda are located on well-drained, lower to 

 upper slopes or ridgelines, at elevations from 

 4,600 to 8,000 feet. Slope angles range from 10- 

 40 percent. This species has also been found 

 growing in small amounts of loose soil, atop rocky 

 calcareous outcrops. 



SOIL RELATIONSHIPS: The four A. fecunda sites 

 that occur along the west slope of the Sapphire 

 Mountains occur on a calc-silicate unit of the 

 Wallace Formation, and are just south of a large 

 granitic intrusion, the Willow Creek Stock 

 (Presley 1971) . 



The A. fecunda sites along the flanks of and in 

 the East Pioneer Mountains occur on the upper part 

 of the Madison Limestone Formation, comprised of 

 metamorphosed limestone and sandstones, and on the 

 Threeforks Formation, comprised of grayish-brown 

 argillaceous limestone (Richards and Pardee 1925) . 

 These substrates appear similar to those occupied 

 by populations along the Sapphire Mountains. 



The distinctiveness of the soils indicates that 

 they are a factor in the distribution of A. 

 fecunda populations. 



On a microsite level, A. fecunda may be associated 

 with cryptogamic soil crusts. Results of a study 

 at Charleys Gulch (001) and Birch Creek (004) in 

 Ravalli County are included in Schassberqer 

 (1988). ^ 



REGIONAL CLIMATE: The regional climate of 

 southwestern Montana is characterized by hot "dry 



