52 Gardening 



gen comes from the water which the roots absorb from 

 the soil. The other seven elements are secured by the 

 plant from various mineral compounds which it takes 

 from the soil. 



The minerals most often lacking in the soil are those 

 that furnish nitrogen, potassium, sulfur, and phosphorus. 

 These are often supplied in manures or other fertilizers 

 (page 66). When the gardener enriches the soil, he is 

 providing raw materials needed in some of the many 

 building operations going on in the plant. 



Garden plants are builders and storers of food. A 

 weed, as a rule, uses its food for growth as fast as it makes 

 it, and in its small seeds it leaves no considerable store of 

 food that can be used by man. But a radish, cabbage, or 

 bean plant makes food faster than it uses it and collects 

 a surplus either for its own future use or for the use of 

 its offspring. These stores of food we take for ourselves, 

 and we have selected for cultivation in our gardens the 

 plants that will lay up for us food in largest amounts. 



The successful gardener gives his plants favorable con- 

 ditions for food manufacture and provides them with 

 abundant supplies of the raw materials tkat they must 

 have for the work. 



Questions 



How does a green plant get its food? What classes of foods 

 do plants build ? What raw materials are used in making them ? 

 Why cannot animals live without plants ? 



What is photosynthesis? In what part of the plant does 

 photosynthesis go on ? When does it go on ? Describe the struc- 

 ture of a leaf. What is the function of the epidermis? How 

 do gases enter and leave the leaf? How do water and minerals 

 get into the leaf ? 



