Ij6 Plants and their Ways in South Africa 



dew and open out as water runs down their inner surfaces. 

 As this water is absorbed the stipules close over the leaves 

 again. ^ 



It would take a much longer chapter than this to tell of all 

 the curious devices by which plants are protected against in- 

 solation or exposure to the direct rays of the sun. One of 



Fig. 103. — Leaves of Cassia in sleep position. 



the most remarkable methods is shown by a group of plants 

 described by Dr. Marloth as possessing "window leaves" 

 {Fenster- Blatter). These plants have the green portion of 

 their leaves underground, only the colourless tips being 

 exposed ; here the light enters and is diffused to the chloro- 

 phyll below. Beneath these " windows " in some plants, for 

 example Mesembrianthemum rhopalophyllu7?i^ S. and D., are found 



1 This plant supplies a ferment which the natives in some curious 

 way have learned to use in raising bread. 



