AGRICULTURAL BOTANY 



175 



that all the legumes are able through the bacteria in 

 the tubercles on the roots to fix free nitrogen, that is, 

 to make a nitrate of the nitrogen in the air. The most 

 familiar of the legumes are beans, peas, lentils, peanuts, 



FIG. 87. Plum and Apple. 



a, plum blossoms ; b, section of flower ; c, diagram of flower ; d , plum ; e, section of apple 

 blossom; /, section of apple. 



clovers, alfalfa, and the locust tree. Some not so 

 familiar are gum arabic, tolu, tragacanth, indigo. 



