13 



other areas within the region where the ranges of 

 the putative parents overlap. 



6. General environment and habitat description. 



A. Concise statement of general environment and 

 habitat: All known clusters of Tr isetum 



or thochaetum occur along the margins of moist to 

 boggy montane meadows, at elevations of ^^60-^510 

 ft. Along these margins, the plants occur under 

 the partial cover of Pinus contor ta , Picea 

 enqelmanni i , and/or Ab ies lasiocarpa . The soil 

 varies from saturated to slightly drained. The 

 meadows are all undisturbed, except for some 

 impacts by moose movement along Granite Creek 

 (habitat slides included on p. 8). 



B. Physical characteristics. 



1 . CI imate. 



a. Koppen climate classification: Type 

 Df b , with average January temperature 

 below 0°C (3E°F), average temperature of 

 warmest month above 10°C OCF) and 

 under £B°C (71.6°F), with no dry season, 

 and the driest month of summer receives 

 more than 3 cm (1.2 in.) of rain 

 (Visher, 195^). 



b. Regional macrocl imate: The nearest 

 principal c 1 imato log ical stations in 

 Montana are located at Missoula 

 (approximately 3^ air miles ENE, 3190 

 ft. elevation) and Stevensville 

 (approximately S8 air miles SE, 3370 

 ft. elevation). Data for the period 

 19^1-1970 are provided by the U.S. 

 Department of Commerce (1973). At 

 Missoula, the mean annual precipitation 

 was 13.3^ inches; the mean annual 

 temperature was ^3.7^, and the mean 

 July temperature was 66.6''F. At 

 Stevensville, the mean annual 

 precipitation was 13.33 inches; the 

 mean annual temperature was ^^.3°F, and 

 the mean July temperature was ^S.S^F. 

 Precipitation was doubtlessly greater in 

 the Bitterroot Mountains near the known 

 sites, where the elevation is about ^500 

 ft. Also, it is likely that mean 

 temperatures were lower. 



c. Local microclimate: No quantitative 

 information available. The meadow 

 margin habitats are generally exposed to 



