128 



AGRICULTURE 



and hay grasses. These plants have fibrous surface roots, long, 

 narrow leaves, and jointed, hollow or pithy stems. Their flowers 

 are usually small and scentless, as they depend upon the wind 

 to carry their pollen. 

 You have already been told something about the legume, or 



PRODUCTIVE AREAS OF THE PRINCIPAL AGRICULTURAL STAPLES OF THE 

 UNITED STATES 



pod-bearing, family, which has the power of using free nitrogen 

 by means of bacteria that live in the tubercles on the roots. 



The rose family, which gives us our most beautiful flowers, 

 is the great fruit family of the north temperate zone. On page 126 

 is a table of our principal crop plants, classified according to 

 families. 



Crop Development. To Asia we owe most of our food plants. 

 They have had their qualities developed by hundreds, even thou- 



