38 UNIVERSITY OF MISSOURI STUDIES [186 



little of these at Ward and on the iiigh slopes "above Bloomer- 

 ville, and on Arapahoe Peak just below timberline, but I am 

 unable to give any clear account of the vegetation.* 



F. ALPESTRESt 



Between 11,000 and 12,000 feet tree-growth ceases ab- 

 ruptly. The spruces and firs bend and hug the ground. The 

 willows branch and fork underground and rise to the height 

 of but a few inches. The precise altitude of the timberline 

 depends somewhat on the exposure, and differs, therefore, 

 from peak to peak, but 11,500 feet is, perhaps, on an average 

 the lower limit of the alpine zone. I am acquainted with this 

 zone only on Arapahoe Peak, where I spent one day, Septem- 

 ber first, and collected some no species, most of them above 

 timberline. The total number of species known to reach an 

 altitude of 12,000 feet, or above, in Colorado is 386.* 



The alpine flora may be conveniently gathered into two 

 societies: a. The wet alpine tundra (Tundrales). b. The 

 dry rock-desert (Alpinae) of the summits. 



a. Tundrales. The wet tundra occupies the region of 

 cold water-soaked soil. The water from the wasting snows 

 collects in depressions, streams are formed, and along these the 



*I refer the reader to the excellent paper on Redrock lake near 

 Ward, by Ramaley and Robbins (Univ. of Colo. Studies, 6, 133-168). 



tConsult for the Alpine Flora Cooper's Alpine vegetation in the vi- 

 cinity of Long's Peak, Colorado (Bot. Gaz., 45, 319-337). He recog- 

 nizes three plant formations: i. The dry meadow. 2. The wet mead- 

 ow. 3. The Krummholtz. The latter, while striking enough, is rather 

 but the upper level of the spruce forest, striving to persist in Alpine con- 

 ditions. 



JFor a list of these see the article by Cockerell on the Alpine Flora 

 of Colorado (Am. Nat., 40, 86-873). 



