Root Pressure 147 



manometer (fig. 293). Sometimes this root-pressure causes an 

 exudation of water in various parts of plants. Examples are 

 to be seen in many Grasses, Aroids, and Alchemilla, where the 

 water escapes in drops along the mar-gins and at the tips of the 

 leaves. 



It is especially in spring that this root-pressure is noticeable. 

 In summer, when active transpiration is going on it is reduced 

 to a minimum. 



L 2 



