21 



b. Specific known pollinators: Bumblebees 

 ( Bombus sp.) have been observed to visit 

 heads on numerous occasions, and may be 

 the primary pollinators. 



c. Other suspected pollinators: Not known. 



d. Vulnerability of pollinators: Not known 

 although bumblebees are ubiquitous and 

 their vulnerability is probably low. 



3. Seed dispersal. 



a. General mechanisms: Numerous seeds are 

 produced that are mostly wind dispersed by 

 the prominent pappus that is about 3 times 

 the length of the small achene. 



b. Specific agents: Primarily wind 

 dispersed. 



c. Vulnerability of dispersal agents and 



mechanisms: The heads of some plants in 

 the Little Belt Mountains have been 

 attacked by a weevil, Rhinocyllus conicus . 

 This weevil was introduced to North 

 America from Europe as a biological 

 control agent for Carduus nutans (Rees 

 1982, 1987). Weevil infestation rates, 

 and the likely effect on seed production 

 and population viability are unknown, 

 although preliminary studies have begun. 



d. Patterns of propagule dispersal: Unknown. 

 .4. Seed biology. 



a. T^ount and variation of seed production: 



Unknown. 



b. Seed viability and longevity: Unknown. 



c. Dormancy requirements: Unknown. 



d. Germination requirements: Seeds of C. 

 longistylum were germinated successfully 

 without cold stratification or 

 scarification (Sarah Mathews, pers. 

 comm.). It is possible that germination 

 occurs in fall. 



