Plant Industries and Climatic Plant Formations 371 



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Fig. 2.37. The coconut palm in fruit. A tree under the 

 best conditions will yield a nut each day in the year. 



The desert region produces abundantly when irrigated. The 

 Salt River Valley, in Arizona, is a good example of what can be 

 done under these conditions. As the valley is located in southern 

 Arizona, however, it has a subtropical climate, and consequently 

 many tropical crops can be grown. Alfalfa and cotton are the 

 most important crops at present ; the date palm has been suc- 

 cessfully transplanted from northern Africa and is now being 

 grown commercially. A great variety of other crops, such as 

 olives, figs, avocados, and tropical pawpaws, are also cultivated, 

 on a smaller scale. 



