hybridize, primarily by the involucral bracts. In C. 

 hooker ianum . the bracts are not dilated and fringed, 

 but are moderately to strongly hairy, while those of C. 

 longistylum are glabrous or nearly so. Recent keys 

 separating C. longistylum from other Cirsium species in 

 Montana are in Dorn (1984) , and Hitchcock and Cronquist 

 (1973) . 



Photographs are included in Section V., pp. 67-71. 



D. GEOGRAPHICAL DISTRIBUTION 



1. RANGE: Cirsium longistylum occurs only in central 

 Montana, primarily in the Little Belt Mountains, with a 

 single recorded occurrence in the Big Belt Mountains to 

 the west. 



2. CURRENT SITES: In 1990, four new populations were 

 mapped and the range of six populations was extended. 

 Figure 1, p. 5, shows the locations of the mapped 

 populations of Cirsium longistylum . The normal 

 approach in rare plant surveys is to locate and map all 

 populations. However, Cirsium longistylum is nearly 

 ubiquitous to many of the meadows and roadsides at 

 higher elevations in the Little Belt Mountains, and is 

 common in moist streamside meadows at lower elevations. 

 Thus, it was decided by the Forest that more emphasis 

 should be placed on thorough collections of plant 

 specimens and monitoring plots. The populations mapped 

 represent only a fraction of individuals and 

 populations observed to be present in the Little Belt 

 Mountains. 



3. HISTORICAL SITES: None. 



4. UNVERIFIED/UNDOCUMENTED SITES: None. 



5. AREAS SURVEYED BUT SPECIES NOT LOCATED: At higher 

 elevations in the Little Belt Mountains where snowpack 

 is maintained through early summer, Cirsium longistylum 

 was observed to be common in open meadows. At lower 

 elevations it was found to occur adjacent to streams 

 and creeks, where soils remain moister later than in 

 the surrounding uplands. 



E. HABITAT: Cirsium longistylum occurs frequently on disturbed 

 roadsides, in meadows and openings in forests. Surrounding 

 vegetation cover ranged from 10 to 95 percent depending on 

 the site. Undisturbed habitats include Pinus 

 contorta/Festuca idahoensis open forest and mixed meadows, 

 and Abies lasiocarpa - Pinus albicaulis open forest and mixed 



