10 Effective Farming 



There will be an exchange of liquids through the bladder, 

 which will be indicated by a rise of the liquid in the tube. 

 In this way water with dissolved plant-food passes into the 

 root through the root-hairs. The walls of the root-hairs are 

 a semi-permeable membrane and the sap in the plants is of 

 greater density than the water solution in the soil. Conse- 

 quently there is a passing of water and dissolved plant-food 

 into the root. 



Function of stems. In most species of plants the stem is 

 the part that supports the leaves. However, in some kinds, 

 the Irish potato and Bermuda-grass for example, underground 

 stems develop, and in certain cacti the stem and leaves are one. 



The parts of a stem where leaf or leaves or other stems are 

 attached are called nodes and the space between adjacent 

 nodes, an internode. Examine several species of plants and 

 locate these parts. 



Function of leaves. The leaves are a very wonderful labora- 

 tory where important changes occur. The food that is taken 

 from the soil and carried in the sap and the carbon dioxide 

 that passes from the air into the leaves through the stomata 

 are united chemically in the leaves and form the various com- 

 pounds of which the plant body is composed. Thus we might 

 think of the leaves as the stomach of the plant. Chlorophyl, 

 the green coloring matter of plants, is necessary in the chemical 

 change that takes place. Chlorophyl forms only in the light. 

 The process by which plants manufacture the food compounds 

 is called photosynthesis. 



The changed food material is carried from the leaves to 

 the different parts of the plant where it is used to build up 

 the plant body. In the elaboration of plant-food not all the 

 water absorbed by the root-hairs is required and the surplus 

 and also some uncombined oxygen pass off through the stomata 

 into the air. 



Function of flowers. Flowers are the reproductive organs 

 of the plant. They are classified as complete and incomplete. 



