THE DUNES AND THEIR PLANTS 



123 



vegetation may grow more luxuriantly. By the time that 

 several generations of cottonwoods, together with many more 



N^al^ 





, '-> 





^ 





^^ ^ 



w 



Fig. 89. — Steep side of a dune with red-osier dogwood, Cornus stolonijera, 

 and bunch grass serving as binders. 



of the shorter-lived shrubs and the associated annuals, have lived 

 and died, the sand has become so altered by their decomposed 



