BOTANICAL GEOGRAPHY 335 



The Pacific Slope is characterized by cone-bearing ever- 

 greens in great abundance in the mountains and along the 

 foothills. Chief among these in point of size are the red- 

 woods and the "big trees" (Sequoias) (Fig. 32). Oaks 

 are represented by a good many species, several of them 

 evergreen. There are many xerophytes, some of them 

 characteristic of alkali regions; and in Southern California, 

 on account of the long dry season, plants with large roots 

 or rootstocks and bulb-bearing plants (many of them 

 belonging to the lily family) are abundant. The tree 

 yucca (P-late VII) is one of the largest and most inter- 

 esting xerophytic plants of North America. 



