Plant Defences 



8i 



storing water in their swollen roots or stems and leaves. The 

 leaves have thick cuticles, which are often incrusted with lime 

 or covered with wax. In the leaf depressions rain and dew 

 may be caught and retained, and the delicately tinted blossoms 

 that crown the labour of these plants declare that Nature need 

 seek no further devices for her Karroo garden. A drink of 

 water from a well driven in the Karroo shows the salty or 

 alkaline condition of the soil, and 

 the fleshy leaves of the Karroo plants 

 remind us of the plants along the salt 

 marshes and sand dunes by the sea. 

 It was once thought that roots ab- 

 sorbed all the water required by 

 flowering plants. The water caught 

 by the leaves of these plants suggests 

 that they also absorb moisture. Notice 

 how the pitcher-like leaves of Saty- 

 ritim and the cups formed by the 

 stipules and leaf bases of Hydro- 

 phyllax catch water. It is possible 

 that these water gatherers are for pre- 

 venting ants from reaching the flowers 

 to rob them of their honey intended 

 for some more serviceable insect. 



A swarm of locusts leaves little 

 green in its path, and in times of 

 drought animals are not fastidious in 

 their tastes for herbage ; unless the 

 juices are bitter or poisonous, plants 

 have to battle in other ways against 

 their living enemies. As a guard against 



destruction from browsing animals, plants are protected by 

 spines or a felt of hair. Hernias gigantca^ the " Tontel- 

 bloom," has the lower leaves well protected by a dense hairy 

 covering on both sides ; as they get older, and their leaves 

 become firmer, they are less in need of protection, and the hair 

 is easily brushed off. 



Instead of exposing the precious store of water above 



G 



Fig. Z^A.—Hydi-ophyllax. The 

 leaves and stipules form a cup 

 which catches and holds rain. 



