INTRODUCTION 



XI 



are much alike, in many cases the word Plain also includes the Sonoran portion 

 of the plains, the so-called Staked Plains, Tables showing the approximate 

 altitudes occupied by the different zones in southe^fi Colorado and southern 

 Montana, and in Alberta at the crossing of the Canadian Pacific Railroad, and 

 also the approximate latitudes at which they meet the plains, lowlands, or level 

 basins are shown below. 



The western side of the mountains is warmer than the eastern. It is also 

 dryer, except in the northern part, where the moisture conditions are reversed. 

 The lower zones, therefore, extend further north on the west side. 



Colorado 



Alpine (Alp.) 3500-4300 m. 



Subalpine (Subalp.) 300O-3500 m. 



Montane (Mont.) . ., 2500-3000 m. 



Submontane (Submont.) ... 1800-2500 in. 

 Upper Sonoran (Son.) 1350-1800 m. 



Montana 



2700-3500 m. 

 2500-2700 m. 

 1800-2500 m. 

 1500-1800 m. 



Plain 



Alberta 



2100-3500 m 

 1800-2100 m 

 1200-1800 m 

 Plain 



This table may be given also in the English measures: 



Alpine 11.500-14,400 ft. 



Subalpine 10,000-11,500 ft. 



Montane 8,000-10,000 ft. 



Submontane 6,000- 8,000 ft. 



Upper Sonoran 4,500- 6,000 ft. 



9,000-12.000 ft. 

 8,000- 9.000 ft. 

 0,000- 8,000 ft. 

 5,000- 6,000 ft. 



Plain 



7,000-12,000 ft. 

 6,000- 7.000 ft 

 4,000- 6.000 ft 



Plain 



The different zones meet the lowlands, plains or level basins at approximately 

 the following latitudes: 



East side 



Alpine-arctic 



Subalpine 



Montane 



Submontane 38° 



Upper Sonoran 



69°-90° 

 55°-09° 



48^-55° 



30' 

 35°-38° 



30' 



West side 



69°-90° 

 55°-69° 

 50^-55^^ 

 42°-50° 

 35°-42° 



Time of Flow'erixg 



At the end of the specific description is given the month of flowering, 

 symbols used are: Ja, F, Mr, Ap, My, Je, Jl, Au, S, O, N, D. 



The 



