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 southern 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 shoA\'n below. 



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

 drj^er, except in the northern part, where the moisture conditions are reversed. 

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



Colorado Montana 



Alpine (Alp.) 3500-4300 m. 2700-3.500 m. 



Subalpine (Subalp.) 3000-3500 m. 2500-2700 m. 



Montane (Mont.) 2500-3000 m. 1800-2500 m. 



Submontane (Submont.) . . . 1800-2500 m. 1500-1800 m. 



Upper Sonoran (.Son.) 1350-1800 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. 



Alberta 



2100-3500 m. 

 1800-2100 m. 

 1200-1800 m. 

 Plain 



9,000-12,000 ft. 

 8,000- 9,000 ft. 

 6,000- 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 69°-90° 



Subalpine 55°-69° 



Montane 48°-55° 



Submontane 38° 30'-48° 



Upper Sonoran 35°-38° 30' 



Time of Flowering 



West side 

 69°-90° 

 55°-69° 

 50°-55° 

 42°-50° 

 35°-42° 



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

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



The 



