I9I9] 



VESTAL— PHYTOGEOGRAPHY OF COLORADO 



177 



areas having climates not widely dissimilar, as the plains of the 

 rain belt and the northern foothills, should have distinctly unlike 

 vegetation. 



Minimum rainfall. — One factor which seems to be partly 

 responsible for th.e generally xerophytic character of the entire 

 region studied, the plains in particular, is the wide variation in the 

 amount of rainfall from year to year. The minima have been 



TABLE IV 



MiNIMtJM ANNUAL RAINFALL 



Two stations within the foothills area are exceptional as to rainfall, and have not been included in the 

 averages. These are Salida in the .Arkansas Valley above the Royal Gorge, and Westcliffe in the Wet Moun- 

 tain Valley. Similarly, Canyon City at the debouchure of the Arkansas, and Raton and Las Vegas in New 

 Mexico, have been excluded from the mountain-front area. The stations with the lowest minima have been men- 

 tioned in the table. The lowest minimum in each area, whether in 1893 or in some other year, is printed in 

 bold face. Except for Cheyenne Wells, which is remote from the mountains, all of the stations noted as having 

 had least rainfall in 1893 are within a limited area (in the northern part of the region), which seems to have been 

 most severely affected by the drought of that year. 



tabulated for the several parts of the region from the climatic 

 summaries of the Weather Bureau. The year 1893 happened to 

 be exceptionally dry, and the minima for many of the stations fall 

 in it. Dryness in other years has been of more local prevalence. 

 It has seemed preferable to present the data for 1893 separately 

 from that of other years. The data for 1893 ^^e not available for 

 all stations in each area, and so the number of stations from which 

 data have been used is mentioned for each area (table IV). The 

 column presenting the average minima for the several areas (minima 



