29 

 Senecio debilis Nutt . 

 I. SPECIES INFORMATION 



A. CLASSIFICATION 



1. SCIENTIFIC NAME: Senecio debilis 



2. COMMON NAME: Rocky Mountain Ragwort 



3. FAMILY: Asteraceae 



4. GENUS: According to Hitchcock and Cronquist (1973) , 

 the genus Senecio is one of the largest genera of 

 plants, containing probably well over 1000 species, 

 of very wide geographic distribution. Many of the 

 species are closely related, often indeed, with only 

 about the degree of distinctness more commonly 

 associated with varieties. An attempt to reach a 

 more conservative treatment frequently necessitates 

 the inclusion of such a large number of highly 

 diverse taxa within the limits of a single "species" 

 as to be wholly impractical. (Name from the Latin 

 senex, an old man, probably referring to the white 

 pappus or hoary pubescence of some species.) 



5. SPECIES: Senecio debilis occurs in moist open 

 meadows, especially in alkaline situations; northern 

 Colorado northwestward through Wyoming to 

 southwestern Montana and adjacent Idaho (Barkley, 

 1978) . 



B. PRESENT LEGAL OR OTHER FORMAL STATUS 



1. BUREAU OF LAND MANAGEMENT: Senecio debilis is 

 proposed as a sensitive species for the Dillon 

 Resource Area. Documentation of it on many BLM 

 lands in the Tendoy Mountains this past year 

 provides basis for recommending that it be dropped 

 from further consideration (Vanderhorst and Lesica, 

 in progress) . 



2. STATE: Senecio debilis is currently listed by 

 the Montana Natural Heritage Program as "critically 

 imperiled because of extreme rarity (5 or fewer 

 occurrences, or very few remaining individuals) , or 

 because of some factor of its biology making it 

 especially vulnerable to extinction" (state rank = 

 SI) . Documentation of it in the Tendoy Mountains 

 this past year provides basis for recommending that 

 it be changed to S3 (Vanderhorst and Lesica, in 

 progress) . 



