50 Gardening 



becomes very abundant in the cells. Some of it is stored 

 as starch within the leaf. But the sugar is also con- 

 ducted to other parts of the plant to be used by them 

 immediately for food or for storage. The tuber of the 

 potato is an enlarged part of the stem where large 

 amounts of starch are stored. The starch that has been 

 stored in a plant can be again changed to sugar and 

 transported to the parts where active growth is taking 

 place or where seeds are being formed. 



But while most plants change their sugar to starch for 

 storage, a few plants do not do this at least not until 

 the sugar has become very abundant in them. From 

 two plants, sugar cane and the sugar beet, the world's 

 supply of sugar is obtained. Onions and sweet corn 

 are rich in sugar, and wrinkled peas contain more sugar 

 than smooth peas. 



The manufacture of fats and proteins. From sugar, 

 plants make oils, in which form many plants store a 

 part of their food. From the olive, coconut, flaxseed, 

 cotton seed, peanut, corn, and castor bean, oils are ob- 

 tained which are used for many purposes by man. 



The fats are present in larger or smaller amounts in 

 all living plant cells. They are for the most part formed 

 in the cells where they are found, and are not to any great 

 extent transported from one part of the plant to another. 

 They contain the same chemical elements as sugar and 

 are believed to be formed from sugar. 



Proteins are made by combining chemically nitrogen, 

 sulfur, and sometimes phosphorus with the elements of 

 the sugar. Minerals supplying these are obtained from 

 the soil. Without an abundant supply of the minerals 



