318 



TYPICAL FLOWERING PLANTS 



beans. Beans are now widely distributed, one or more 

 varieties being grown in all temperate regions. 



The value to the soil of the plants of the Pulse family 

 has long been known, bat the reasons for it have not been 

 understood until recently. As we have seen, bacteria in 

 the roots of beans gather nitrogen which goes to replace 

 that drawn from the soil by other plants. Soils which 



lack nitrogen may be 







improved by growing 

 on them a crop of 

 the pulse family and 

 then plowing it under. 

 This method of enrich- 

 ing the soil is known 

 as " green manuring." 

 See page 270. 



The bean family in- 

 cludes such well-known 

 plants as peas, peanuts, 

 clover, and alfalfa. The 

 peanut has the peculiar 

 habit of thrusting its 

 blossoms into the ground after they have been polli- 

 nated. The pods mature there and are harvested by 

 digging. 



234. The Raising of Corn. — Most of the work of planting, 

 cultivating, and harvesting corn is done by machinery. 

 Hand work is necessary only in removing the ears from 

 the stalk and the husk from the ears. Because corn is so 

 valuable a food for men and animals and because so much 

 of the work necessary in raising it can be done by machin- 

 ery, corn raising has become one of the most important 

 industries on the easily cultivated level prairies of the 

 Middle West. 



Figure 339. — Peanuts. 



