Vol. n Hall. — Botanical Survey of San Jacinto Mountain. 47 



ORIGIN AND AFFINITIES OF THE SAN JACINTO 



FLORA. 



On examining the flora of the San Jacinto Mountains we find 

 it to be composed of two quite distinct elements; the one plainly- 

 boreal in its character, the other austral. In the Transition 

 Zone, which comprises the broad, middle belt on the mountain, 

 these two floras intermingle and often lose something of their 

 distinctive characteristics, so that it becomes difficult to say just 

 where one terminates and the other begins. Since these were 

 evidently derived from two diflPerent sources they are here sep- 

 arately considered . 



The Boreal Element. 



By taking a list of all the species of plants found growing in 

 the Alpine, Hudsonian and Canadian Zones of San Jacinto 

 Mountain we have a very good representation of the flora of the 

 higher mountains of Southern California. A list of these, 

 which has been prepared but which it is not necessary to repro- 

 duce here, shows that there are 129 such species represented and 

 that of this number 10 species are limited to Southern California, 

 5 are restricted to Southern California, Arizona, and New Mexico, 

 and 15 are generally distributed over the Northern Hemisphere; 

 while the remaining 99 are common to the mountains of Southern 

 California and the Sierra Nevadas. By adding the 15 species of 

 general distribution to the last number, we have 114 species or 

 about 88% of the flora of the higher portion of San Jacinto 

 Mountain represented in the Sierras. Of these 114 species 

 at least 46 occur also in the Rocky Mountains. It is there- 

 fore evident that the boreal flora of San Jacinto Mountain has 

 its affinities with the flora of the high ranges extending northward 

 throughout the state and, through this, with the flora of the 

 Rock}^ Mountains. 



In this connection it is instructive to compare the San Jacinto 

 flora with that of the San Bernardino Mountains, since it would 

 seem probable that any northern species reaching the former 

 would pass by way of the latter. Of the 114 boreal species 

 selected above as being common to the San Jacinto Mountains 



