50 University of California Piehlieations. [botany 



The Austral Element. 



Covering all the lower slopes and rnnning well n]) into the 

 Transition Zone is found a flora very different in character and 

 affinities from that just discussed. The i)lants are remarkable 

 in their adaptation to an arid environment, and therefore 

 approach those of the desert regions in this respect. In fact 

 many of the species extend well out along the low ranges of the 

 Colorado Desert, and there can be little doubt that the floras of 

 these two regions are closely related. Since so little is known 

 of the flora of southeastern California and northern Mexico it 

 is impossible to give the actual number of San Jacinto plants 

 occurring in either of these regions, l)ut it is probable that quite 

 a number of species are common to all three. 



Besides the strictly austral element, many of the foot-hill 

 species are restricted to Southern California. These are often 

 quite common and well distributed throughout the foot-hill 

 region of the southern part of the state and, although they have 

 probably migrated somewhat in past ages, still we may consider 

 them as native Southern Calif ornian plants. 



The Presence of Arizonan and New Mexican Species. 



There still remain for consideration a few plants which 

 apparently have no affinity with any other Californian flora, but 

 which occur in the mountains of either Arizona or New Mexico 

 or both. These are PJiiladeJpJius serpijUif alius, Pentstemon 

 Boihrockii, Geranium Fremontii, Trifolium Eushyi and Lilium 

 Parry i, the first three of which have not yet been found else- 

 where in California, while the last two have also been collected 

 in the San Bernardino Mountains. With the exception of the 

 last, which runs down into the Lower Transition, all are 

 restricted in their range to the Canadian and Upper Transition 

 Zones, and therefore cannot possibly connect with those of 

 Arizona and New Mexico by way of the desert ranges. We are 

 then confronted with the question as to the manner in which 

 these entered Southern California or, in case they originated 

 here, by what route they have been able to cross over into 

 Arizona and New Mexico. 



