EXERCISE 44 



The water taken in by the roots of a plant rises in the stem for several reasons. 

 Three of these are (i) root pressure, (2) capillary attraction, and (3) the lifting force of 

 evaporation of leaves, called transpiration. 



Problem. Can water be absorbed by the root with enough force to raise it above 

 the earth ? 



What to use. A potted hydrangea or other convenient plant with stem half an inch 

 thick at the base ; rubber tube for connection ; glass tube ; water. 



What to do. Place flowerpot with plant in a tub of water so that the earth is covered. 

 Cut the stem under water to prevent entrance of air bubbles ; attach the glass tube above 

 the stem with the rubber coupling. Take out of the tub and support the glass tube in 

 a vertical position. Mark the level of water in the tube from time to time. 



Record. Describe results of the experiment and give your conclusions. 





Questions. 1. In what ways does absorption by the roots resemble osmosis? 



2. Would water be absorbed more easily from a soil that had much material in solution or from 

 one that had very little material in solution ? Why ? 



