166 S. B. PARISH 



mation to the value of the temperature coefficient. There are 

 no records of the atmospheric humidity, but this must of neces- 

 sity be low in a limited area surrounded by extensive regions of 

 great aridity. 



It will be readily understood that this narrow ridge, however 

 lofty its summits, facing on every side deserts and arid hills and 

 plains, can have no other than a xerophytic flora; and such, with 

 but few exceptions, is its character. The great majority of the 

 plants — trees, shrubs and herbs — exhibit in various degrees the 

 famihar modifications characteristic of xerophylly. 



For the same topographical reasons the zonation of this flora 

 is far less well defined than that of mountains more favorably 

 situated and of greater extent. Yet nowhere else in America 

 save on the adjacent San Jacinto Mountain, is there displayed 

 in such close conjunction so wide a range of phytogeographic 

 regions. The two deserts at the north and east are occupied by 

 a Lower Sonoran flora, and members of it and cognate species 

 abound on the sides of the mountains which face them; the 

 flora of the opposite base is Upper Sonoran and greatly, but not 

 as greatly, modifies that of the southern ascent. The less tilted 

 area between is covered by a Transition coniferous forest; above 

 this, on the flanks of the culminating peaks, the Canadian and 

 Hudsonian regions are represented; and at the very summit of 

 San Gorgonio, above the tree fine, are to be found a few Arctic- 

 Alpine plants. From various local conditions this zonation, 

 especially above the Transition, is interpenetrating and often 

 confused, but it has a real and distinguishable existence. 



In the following catalogue an attempt is made to define the 

 zonal distribution of the different plants, so far -as the writer's 

 knowledge of it permits. Further investigations will doubtless 

 correct the assigned distribution in some instances, but it is 

 believed to be fairly accurate. 



The southern slope of the mountains is covered with a close 

 growth of shrubs, the trees and herbs being mostly confined 

 to the bottoms and sides of the numerous canons, most of 

 which carry permanent brooks. This is called the Chaparral 

 Zone; the Lower Chaparral extends from 1500 to nearly 3000 



