The Leaf 107 



the water more quickly than the root can suck it from 

 the parched ground. Then the leaves begin to flag and 

 hang limply down until the falling dew freshens them 

 up again. In damp weather the stomata open, as when 

 the air outside is moist evaporation will in any case be 

 slow. 



Fig. 54. Leaf of Guelder Kose, showing blade, stalk, and stipules. 



A typical leaf such as that of the plum or guelder 

 rose has two parts besides the blade, namely a thin 

 flexible stalk, and at the base of the stalk two small 

 green leaves known as stipules (Fig. 54). These stipules 

 vary greatly in size in different kinds of leaves. In some 

 they are larger than the blade itself, in others they are 

 either altogether absent or drop off almost as soon as 



