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4. Dominance and frequency of the taxon: Cirsium 

 lonqistylum is often present in great 

 abundance, as was noted in 3 sample plots where 

 densities ranged from 0.24 to 2.18 plants/m^. 



In other areas only one or two plant will occur 

 along a roadway. 



5. Successional phenomena: Cirsium lonqistylum 

 has been observed in forest habitats, but only 

 along streams, and generally in more open 

 sites. Populations most often occur in meadows 

 and forest openings. This species would 

 probably not tolerate canopy closure. 



6. Dependence on dynamic aspects of biotic 

 associations and ecosystem features: This 

 species appears to be dependent on habitats 

 that are moist in early summer through snow 

 melt, or mesic riparian habitats where moisture 

 levels are higher than the surrounding uplands. 



7. Other endangered, threatened, rare, or 

 vulnerable species occurring in habitat of this 

 taxon: Two rare plant species have been found 

 on at least two sites where C. lonqistylum 

 occurs. These species include. Phlox kelseyi 

 var. missoulensis (U.S. Fish and Wildlife 

 status 3C, U.S. Forest Service, Region 1 watch 

 list species) and Claytonia lanceolata var. 

 flava (U.S. Fish and Wildlife status C2 , U.S. 

 Forest Service, Region 1, sensitive list) (U.S. 

 Department of Interior 1990, U.S. Department of 

 Agriculture 1988) . 



7. Population biology of the taxon. 



A. General summary: Populations of C. lonqistylum 

 usually Qontain several hundred to tens of thousands 

 of individuals. This species is a perennial that 

 reproduces both asexually by biennial offsets from a 

 perennial rhizome (Moore and Frankton 1963) , and 

 sexually by seeds produced from perfect flowers. 

 Observations of populations indicate a good range of 

 plants at each life history stage, from single whorl 

 rosette, through multiple whorl rosettes, to 

 flowering and fruiting adults. It is not yet 

 certain that this species, is a strict biennial. 



B. Demography. 



1. Known populations: Cirsium lonqistylum is a 

 Montana endemic. There are currently twenty 



