agrestis, A. adsurgens , A. atropuhescens , A. drummundii , 

 and A. lentiginosus . The Kate Creek population on the 

 Beaverhead National Forest occurs in a big 

 sagebrush/mixed bunchgrass community with scattered, 

 small limber pine (Pinus flexilis) . A photographic slide 

 showing the habitat of the Kate Creek occurrence is 

 attached at the end of this report. 



2. Topography: Barneby (1964) describes the settings of 

 Astragalus scaphoides throughout its range as "open 

 valleys, low hills, (and) canyon benches ... from 3,500- 

 6,000 feet." This describes the landforms where the 

 species occurs in Montana, however, the elevation at some 

 sites is somewhat higher and populations are often 

 confined to warm, southerly facing aspects or micro- 

 aspects. In the Tendoys, the species occurs on gentle to 

 moderate slopes in the foothills of the western flank of 

 the range from 6,800-7,100 feet. 



3. Soil relationships: In Montana, Astragalus scaphoides 

 grows in dry soils ranging from clayey to gravelly and 

 stony loams. The soils are derived from limestones, 

 volcanics, and basin sediments. At Kate Creek the main 

 population grows in limestone derived soil while a 

 smaller subpopulation is on a soil of undetermined parent 

 material, possibly volcanic. 



E. POPULATION DEMOGRAPHY AND BIOLOGY 



1. Demographic details: The Kate Creek population is of 

 medium size, consisting of an estimated 500-1,000 plants 

 scattered over 7 acres in 2 subpopulations. On July 28, 

 1994, approximately 15% of the plants were vegetative, 

 15% had mature fruit, and 70% had inflorescences of 

 aborted flowers or were browsed. Most populations of 

 Astragalus scaphoides in Montana are smaller but the 

 Johnson Gulch occurrence on BLM land in the Tendoys is 

 relatively large, consisting of an estimated 1,000-5,000 

 plants. 



2. Reproductive biology: Reproduction is by seed. The low 

 numbers of successfully reproducing plants at Kate Creek 

 suggests that seed production may be a major limitation 

 to population size and distribution of Astragalus 

 scaphoides in Montana. This conclusion is supported by 

 data from other Montana populations where low percentages 

 of flowering plants and high percentages of aborted 

 flowers have been documented. Browsing of flowering 

 heads, probably by cattle, has also been observed at Kate 

 Creek and other sites. Some differences in reproductive 

 success were noted between the two subpopulations at Kate 

 Creek in 1994, a hot, dry season; the main population, 



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