A. Primary succession in the climax chaparral region: lichens and mosses 



on rock surface; Adenostoma, Arctostaphylos, and Yucca as crevice 

 pioneers. Cuyamaca Mountains, San Diego County. 



B. Later stage of succession, showing the preeminent importance of the 



crevices. Same locality as the last. 



C. Fully developed chaparral (Adenostoma consociation) with Yucca 



whipplei. Same locality as the last. 



