VEGETATIVE LIFE ZONES OF THE ROCKY 

 MOUNTAIN REGION 



P. A. Rydberg 



The New York Botanical Garden 



It was twenty years ago last J.une that I had my first intro- 

 duction to the flora of the Rocky Mountains proper. Even 

 before that time I had spent three summers in the foothills in 

 western Nebraska and in the Black Hills of South Dakota. While 

 being principally occupied in a botanical survey from a taxonomic 

 standpoint, during the eleven summers spent in the Rocky Moun- 

 tain region, I could not help making some observations on the 

 general phytogeography of the country. As very little has been pub- 

 lished on this subject, and as some of that little is quite misleading, I 

 thought it advisable to place on record these observations of mine, 

 however incomplete they may be. They were made rather inci- 

 dentally, and could not be otherwise. I therefore began publishing 

 in the Bulletin of the Torrey Botanical Club a series of articles under 

 the heading " Phytogeographical notes on the Rocky Mountain 

 region." The present paper should in reality have been the 

 first of these articles as an introduction to the more specialized 

 topics already begun. 



The Rockies extend from the neighborhood of Santa Fe, New 

 Mexico (about Lat. 35° 30'), to near Lat. 65° in the Yukon Terri- 

 tory, and the different parts must show great variations in the 

 flora. The flora of the region north of Lat. 55° is practically 

 unknown to me, and that of the Canadian Rockies south of 55° 

 I know only from the collections made by others, but such are 

 well represented in the herbarium of the New York Botanical 

 Garden, as the Geological Survey of Canada has let us have the 

 first set of their duplicates for years. 



As I have already pointed out in one of my articles printed 

 last January, the Rockies south of Lat. 55° can be divided into 

 two parts: The Southern Rockies from the Santa Fe Mountains 

 in New Mexico to the Medicine Bow Mountains in southern 



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