8 



2000-3000 feet (600-900 m) lower than most of the sites 

 in the Little Belt Mountains. Thus, precipitation is 

 likely to be higher and temperatures on the average 

 lower at the sites where populations occur. For the 

 period 1951-1980 (U.S. Department of Commerce 1982), 

 the January mean temperature was 20.5°F (-6.4°C), the 

 July mean temperature was 65.2°F (18.5°C), and the 

 annual mean temperature was 44.2°F (6.8°C). The mean 

 annual precipitation was 15.3 in (38.3 cm) with May 

 (3.01 in (7.5 cm)) and June (3.07 (7.7 cm)) being the 

 wettest months. 



F. POPULATION DEMOGRAPHY AND BIOLOGY 



1. PHENOLOGY: Flowering occurs from late June to late 

 August. Variation can be expected over the attitudinal 

 range of occurrence (about 4700 ft (1504 m) to more 

 than 8000 ft (2415 m) , with populations at lower 

 elevations and on warmer aspects flowering earlier than 

 those at higher elevations and on cooler aspects. 



2. POPULATION SIZE AND CONDITION: Cirsium lonqistvlum is 

 nearly ubiquitous within upper elevation moist meadow 

 and roadside sites within the Little Belt Mountains. 

 Only at lower elevations where moist sites are limited 

 to creeks, streambeds and smaller moist meadows, do C. 

 lonqistylum populations become more easily defined. 

 The recorded populations range from 100 individuals 

 covering 5 acres, up to tens of thousands of 

 individuals covering 800 acres. 



3. REPRODUCTIVE BIOLOGY 



a. TYPE OF REPRODUCTION: Cirsium lonqistvlum 

 apparently 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 

 larger multiple whorl rosettes, to flowering and 

 fruiting adults. It is not yet certain that this 

 species is a strict biennial. Small (single 

 whorl) to large (multiple whorl) rosettes were 

 observed in populations as well as flowering 

 plants where the stem had bolted. Results of 

 intensive studies started in 1990 should give a 

 better indication of life history traits exhibited 

 by this species. 



b. POLLINATION BIOLOGY: The pollination mechanisms 

 are not known for Cirsium lonqistvlum . It is 



