t 



i 



6. Locations known or suspected to be erroneous 

 reports: 



a. Montana: None. 



C. Biogeographical and phylogenetic history: Details 

 unknown and not yet investigated. The 

 distributional pattern of C. lonqistylum in Montana 

 may be the result of geographical isolation and 

 speciation. The Little Belts escaped glaciation 

 during the ice ages because it was too low to catch 

 the enormous quantity of snow that big glaciers 

 require (Alt and Hyndman 1986) . 



6. General environment and habitat description. 



A. Concise statement of general environment and 

 habitat: Cirsium lonqistylum occurs frequently on 

 disturbed roadsides, and 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 meadows near 

 upper treeline. 



B. Physical characteristics. 

 1. Climate. 



a. Koppen climate classification: According 

 to Koppen 's classification, the Little 

 Belt Mountains fall within a area where a 

 steppe climate with a winter dry season 

 caused by winter cold prevents appreciable 

 precipitation accumulations (Visher 1954) . 

 This steppe climate is probably typical of 

 the surrounding prairies, but it is likely 

 that the mountains receive higher winter 

 precipitation. 



b. Regional macroclimate: The regional 

 climate of central Montana is 

 characterized by hot, dry summers and 

 cold, snowy winters. The precipitation 

 peak in central. Montana is generally in 

 May and June, and comes in the form of wet 

 snow and rain (U.S. Department of Commerce 

 1982) . 



