I. INTRODUCTION 



SCIENTIFIC NAME: Astragalus molybdenus Barneby. 



COMMON NAME: Leadville milk-vetch. 



FAMILY: Fabaceae (= Leguminosae ; Pea Family). 



The first known collection of Astragalus molybdenus was made 

 in 1873, in the Park Range of Colorado (Barneby 1964). 

 Barneby (1949) initially named the species A. plumbeus . 

 However, since this name had already been applied to a 

 different species in Russia, he subsequently renamed it A. 

 molybdenus (Barneby 1950) . Within the genus, A. molybdenus 

 was placed in the Phacoid group, in section Minerales . The 

 Phacoid group is thought to be the most primitive one within 

 the genus. The chromosome number for A. molybdenus remains 

 unknown. Once this information is obtained, it may suggest 

 that its affinities lie elsewhere in the genus (Barneby 

 1964) . 



For many years, A. molybdenus was known only from alpine 

 areas near Leadville and Aspen, Colorado. In 1982, an 

 Astragalus specimen was collected, in flower, on Mount 

 Wright, Teton County, Montana (Lackschewitz et aX 1984). 

 Although the specimen lacked ripe pods, Rupert Barneby (New 

 York Botanical Garden) identified it as Astragalus 

 molybdenus ; he felt it was different from collections of A. 

 shultziorum . a very closely related species recently 

 described (Barneby 1981) from western Wyoming (Klaus 

 Lackschewitz, pers. comm.). This station on Mount Wright 

 represented a disjunction of approximately 960 km (600 mi) 

 northward from the A. molybdenus populations in Colorado. 

 Thus, the range was divided, with A. shultziorum occurring 

 between the Montana and Colorado locations of A. molybdenus . 



Owing to the overall morphological similarities between A. 

 molybdenus and A. shultziorum , the specific status of the 

 latter has been questioned. Dorn (1988) treated A. 

 shultziorum as a synonym of A. molybdenus . Thus, in 1989, 

 the Montana Natural Heritage Program and the V'Jyoming Natural 

 Diversity Database initiated status survey projects that 

 included an assessment of the taxonomic relationship of 

 these species. The Lewis and Clark National Forest and the 

 Montana Natural Heritage Program established a challenge 

 cost-share agreement. The goals of this project were: 1.) 

 to study the distribution of A. molybdenus populations on 

 the Forest, 2.) to collect specimens that would allow more 

 detailed comparison of the Montana and Colorado populations 

 with those of A. shultziorum from Wyoming, and 3.) to 

 collect leaf samples for use in molecular systematic 

 studies. It was hoped that the taxonomic status of the 



