slopes, at 6,200 ft. in elevation. 



I.6.C.I. Vegetation, physiognomy and conununity 



structure: The vegetation associated with A. 

 fecunda at the Cattle Gulch (013) site would 

 be classified as a Cercocarpus ledifolius 

 (curly-leaf mountain mahogany) / Agropyron 

 spicatum (bluebunch wheatgrass) habitat type 

 as described by Mueggler and Stewart (1980) . 



I.6.C.3. Species associated with Arabis fecunda at 



Cattle Gulch (013) include Artemisia frigida 

 (fringed sagewort) , Gutierrezia sarothrae 

 (broom snakeweed), Physaria geyeri (Geyer's 

 twinpod) , Linum perenne (blue flax) , Senecio 

 canus (wooly groundsel) , Cymopterus 

 bipinnatus (fernleaf spring parsley) and 

 Opuntia polyacantha (plains pricklypear) . 



I.6.C.4. Dominance and frequency of this taxon in the 

 community type: The canopy cover of A. 

 fecunda at Cattle Gulch (013) is quite low 

 (less than 1%) , which is somewhat lower than 

 other known populations. 



I.6.C.7. Other endangered, threatened, rare, or 



vulnerable species occurring in the habitat 

 of this taxon: Mimulus suksdorf ii and 

 Astragalus platytropis , two plants of limited 

 distribution in Montana occur with Arabis 

 fecunda at Cattle Gulch. Mimulus suksdorf ii 

 is currently known from only one other 

 location in southwestern Montana. Astragalus 

 platytropis is known from six other 

 locations, also in southwestern Montana. 



I. 7. A. General svumnary of population biology of the 



taxon: There are about 127 A. fecunda plants 

 in the Cattle Gulch (013) population, in an 

 area covering 60 acres. 



I.7.B.I. Known Populations: One new population of A. 

 fecunda was discovered during the 1989 field 

 season. This brings the total number of 

 known populations to 13, all of which occur 

 in Montana. Nine of these populations occur 

 along the north and east flanks of the 

 Pioneer Mountains, Beaverhead and Silver Bow 

 counties, while the other four populations 

 are found along the western foothills of the 

 Sapphire Range in Ravalli County. 



