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Astragalus terminalis Wats. 



RAILHEAD MILKVETCH 



Bean Family (Fabaceae) 



CONSERVATION STATUS: 



U.S. Fish and Wildlife Service: None. 



Montana Bureau of Land Management: Proposed sensitive in the draft list circulated in 1995. 



Montana Natural Heritage Program rank: G3G4-S2. 



DESCRIPTION: Railhead milkvetch is a tufted perennial herb with several erect stems, 5-30 cm (2-12 

 in.) high, fi"oni a taproot. The leafy stems are short though caulescent. The pinnately compound leaves 

 are 5-20 cm (2-8 in.) long with 13-21 oblong leaflets that have blunt tips. Foliage is sparsely covered 

 with gray hairs that branch at the base and spread in opposite directions appressed to the surface of 

 leaves or stem. Inflorescences are borne in the axils of upper leaves and have 10-30 spreading, crowded 

 flowers that become more remote as the plant matures. White, pea-like flowers are 12-16 mm long with 

 a reflexed upper petal and a purple-spotted lower petal. The calyx is covered with white or black hairs 

 and is 4-5 mm long. Glabrous, cigar-shaped fruits lack a basal stem, are 3-sided in cross-section, and are 

 15-20 mm long (Figure 30; Appendix D-7). The alpine ecotype is much smaller than plants from the 

 valleys (Lesica and Vanderhorst 1995). 



Astragalus terminalis is similar to A. scaphoides and A. atropubescens but can be distinguished by the 

 nearly sessile fruits, while fruits of the other 2 species have stalks that are 3-20 mm long. 



GEOGRAPHIC DISTRIBUTION 



Global distribution: East-central Idaho, northwest Wyoming, and southwest Montana. 



Montana distribution: 1 1 occurrences in southern Beaverhead and Madison counties: the 

 Grasshopper Study Area, the Centennial Mountains, the Sage Creek Study Area, the Tendoy 

 Mountains, and the Upper Madison Valley Study Area. Almost all sites are on ELM lands 

 (Figure 31). 



Grasshopper and Upper Madison Valley distribution: The Grasshopper Study area has 3 

 occurrences, and the Upper Madison Valley has 3 occurrences. The plant is also known from the 

 Sage Creek study area (Lesica and Vanderhorst 1995; Figure 31). 



HABITAT: For the Intermountain region, Barneby (1989) describes the habitat as "open stony hillsides 

 and benches along rivers, commonly associated with low sagebrush and calcareous bedrock." This is 

 consistent with its habitat in the study areas, while in Montana as a whole. Astragalus terminalis occurs 

 over a range of elevations from grasslands and open eroding slopes in the valleys to near timberline from 

 5560-9560 ft. It consistently occupies relatively barren settings that tend to be alkaline. 



