﻿Rydberg: Phytogeographical notes 23 



spruce and the Subalpine fir in the upper part are common; but at 

 an altitude of 5,000 or 6,000 feet, are met with the western tama- 

 rack or larch, silver fir, western hemlock, white cedar and western 

 white pine. 



The Western Tamarack, or Larch, Larix occidentalis, grows 

 at an altitude of from 3,000 to 6,000 feet or rarely 7,000 feet, and 

 always close to the water courses. It is a tree 60-150 feet high and 

 2-4 feet in diameter. Further west it sometimes attains a height of 

 250 feet and 6-8 feet in diameter. It ranges from British Columbia 

 to western Montana and Oregon, east of the Cascades. No sta- 

 tion east of the divide has been recorded, as far as the writer knows. 



The Silver Fir, Ahies grandis, grows up to an altitude of 6,000 

 feet, rarely 7,000 feet. Near the Pacific coast it attains a height 

 of 250-300 feet and a diameter of 4 feet, but in the mountains it 

 seldom becomes more than 100 feet high and 2 feet thick. Its 

 distribution is from Vancouver Island to western Montana, Idaho 

 and northern California. It hardly crosses the Continental 

 Divide in northern Montana, but has been reported from the 

 Yellowstone National Park. 



The Western Hemlock, Tsuga heterophylla, grows up to an 

 altitude of 6,000 feet. On the coast it becomes a tree 200 feet 

 high. It is distributed from British Columbia and western 

 Montana to central California. It, as well as the next, barely 

 crosses the Continental Divide north of St. Mary's Lake. 



The White Cedar, or western arbor- vitae, Thuya plicata, grows 

 also up to about 6,000 feet. It is a tree sometimes 200 feet high 

 and with buttresses 15 feet in diameter, but in Montana it is much 

 smaller. Its distribution extends from Alaska to western Montana 

 and northern California. 



The Mountain White Pine, Pinus monticola, extends to about 

 the same altitude in Montana, but much higher in California. It 

 is generally a tree 100 feet high and 4-5 feet in diameter, rarely 

 larger. It grows mostly on bottom-lands and along streams. 

 Its distribution is from British Columbia and northwestern 

 Montana to Kern County, California. It is not found east of the 

 divide in northern Montana, but has been reported in southern 

 Montana from the valleys of Davis and Slough Creeks north of 

 the Yellowstone National Park. 



