ISematfcg on tlje &>i$ttibution of 



plants in Coloraoo (0ajst 



of tyt TOioe 



Francis Ramaley 



To understand the character of the 

 vegetation on the eastern slope of the 

 Rocky Mountains it is necessary to know 

 something of the climate. It may be 

 said at the start that this is an arid 

 region. The annual rainfall on the 

 plains and in the lower foot-hills is about 

 30 cm. This is not evenly distributed 

 throughout the year, but about one-half 

 of the total precipitation occurs in the 

 spring months. The summer, autumn 

 and early winter are very dry. Occa- 

 sional local showers in summer or snow- 

 falls in autumn are not enough to lay 

 the dust. In the high altitudes there is, 

 however, somewhat more moisture than 



