HOW TREES AND PLANTS IMPROVE THE LAND 87 



been grown where cowpeas had been the year before as 

 where no soil-improving crop had grown. 



How to know plants that improve the soil. The plants 

 that are most valuable for plowing under to enrich the land 



FIG. 55. LEAVES OF LEGUMINOUS PLANTS 



i, bean; 2, hairy vetch; 3, pea; 4, Alsike clover; 5, red clover; 6, white clover; 

 7, sweet-pea; 8, peanut; 9, black locust ; 10, sweet clover: u, alfalfa; 12, soy- 

 bean. 



are all closely akin. The clovers, cowpeas, vetches, and 

 similar plants belong to the bean family. Legumes, or 

 leguminous plants, is the name given to them. All of the 

 legumes the farmer makes use of have flowers shaped like 

 the flower of the garden pea, sweet-pea, and cowpea. The 



