CHAPTER VII 

 THE WATER IN PLANTS 



51. Why Plants Need Water. Plants use water in 

 three essential ways: (1) It combines directly with 

 carbon dioxid to form plant substance; (2) it acts as 

 a solvent for the minerals absorbed from the soil; (3) it 

 serves to make the plant rigid. Young, succulent stems 

 are dependent on water for their rigidity. If water 

 escapes, they wilt and lose the power of carrying on 

 their work. Water is necessary for plants in other 

 ways. It is present in all parts. 



52. The Movement of Water within the Plant. There 

 are special channels for conducting the water from the 

 roots to the stems and leaves. The water is absorbed 

 by the roots and is transported in special water-conduct- 

 ing vessels through the stem and leaves. These chan- 

 nels may be easily marked by placing the soft stem of 

 some plant in a glass of blueing or of diluted red ink. 

 The coloring matter will be carried along with the water 

 and the path through which it moves will be shown. 

 This experiment should be made and closely observed 

 by all. Cut cross-sections of the stem to notice the 

 channels through which the water travels. Leafy stems 

 of balsam, begonia, Johnson grass, poke-berry, and 

 other common plants, make good illustrations. 



53. The Amount of Water in Plant Substance is con- 

 siderable, as may be seen from the following table show- 

 ing the approximate amount of water in a number of 

 common plants. 



(32) 



