324 THE VALUE OF GREEN PLANTS TO MAN 



Cabbage Onions 



Leaves used as food. 



Lettuce 



beet tops, kale, spinach, broccoli, are examples. A cabbage 



head is nothing but a big bud which has been cultivated by man. 



An onion is a compact budlike mass of thickened leaves which 



contain stored food. 



Stems as Food. — A city child, if asked to name some stem used 



as food, probably would mention either asparagus or celery. We 



sometimes forget that one 

 of our greatest necessities 

 comes largely from the 

 stem of the sugar cane. 

 An average of over 100 

 pounds of sugar is used 

 each year by each person 

 in the United States. To 

 supply the growing de- 

 mand for sugar, beets 

 are now being raised in 

 many parts of the world, 

 so that nearly half the 

 total supply of sugar comes 

 from this source. In this 

 country we produce al- 

 most six times as much 



sugar from beets as from cane. Maple sugar is a well-known 



commodity which is obtained by boiling the sap of sugar maples 



Celery Kohl-rabi Potato 

 Stems used as food. 



Sugar cane 



