rydberg: vegetative life zones of rocky mountains 495 



but neither reaches the Rockies proper. The latter sends up 

 three such tongues, one along the Colorado of the West, another 

 along the Virgin River, and the third along the eastern slope of 

 the Sierra Nevada. Only the first of these may be considered 

 in connection with the Rocky Mountains, as a few plants be- 

 longing to this zone reach the foot of the mountains along the 

 Grand and the San Juan, two rivers of the Colorado River system. 

 On the Pacific Coast there are two other regions belonging to the 

 Lower Sonoran Zone, viz. the Sacramento-San Joaquin Valley 

 and the Lower Californian region. In the East this is represented 

 by the humid Austro-Riparian Zone. It is the region of the 

 Long-leaf and Loblolly pines, magnolias, cypress, tupelo, and 

 live-oaks. It corresponds to the regions of oranges and date 

 palms in the Mediterranian Region. 



Summary 



The results of my investigations show, as far as the native flora 

 is concerned: 



1. That the United States may be divided into three floral 

 provinces, an eastern or Alleghanian, a middle or Rocky Mountain, 

 and a western or Pacific. As far as the native flora is concerned. 

 Dr. Merriam is wrong in his contentions that no such a division 

 exists in nature. 



2. That going north and south or down the mountains one may 

 recognize six life zones in the Rocky Mountains. My observa- 

 tions in that respect agree with those of Dr. Merriam, but I have 

 used different names, names that have been used by phyto- 

 geographers in Europe. They are: 



1. Alpine- Arctic. 



2. Subalpine-Subarctic, or Hudsonian of Merriam. 



3. Montane-Boreal, or Canadian of Merriam. 



4. Submontane-Subboreal, or Transition of Merriam. 



5. Upper Austral or Upper Sonoran. 



6. Lower Austral or Lower Sonoran. 



3. That the Arctic-Alpine Zone is practically the same in all 

 three divisions, as it is essentially all over the world. 



4. That the composition of the flora of the corresponding life 

 zones of the eastern and middle divisions otherwise show greater 

 differences than even the parallel zones of the same division, and 



