REGIONAL DISTRIBUTION 



509 



Fig. 379. Tree yucca in the ilohave Desert 

 Redrawn from a photograph by Coville 



At Stanford Unh-ersity, thirty miles south of San Francisco, 

 the rainy season usually begins in October and lasts until 

 April. June, July, August, and September are usually rain- 

 less. At San Diego the diy season begins in April and lasts 

 for seven months. "S'egetation begins with the autumn rains 



