Plant Defences 



77 



that the vapour can pass out but a drop of rain will not 

 run in. 



Phylica and the heaths usually have small needle-shaped 

 leaves ; their edges are rolled back so as to form partially 

 enclosed channels on the under side where the stomata are 

 placed. These channels are protected by a lining of hairs, 

 making sometimes a close white mat. For similar purposes of 



Fig. 79. — Crassitla fyramidalis. 



protection many plants have strongly ribbed stems ; it is within 

 these ribs that the stomata lie. 



Our finest heaths are found in the Caledon and Riversdale 

 districts. Compare the rainfall of these regions with that of 

 neighbouring districts. 



Fortunately for the plants, these waterproof garments are 

 also useful summer styles. The hairs reflect the bright light 

 from the plant, and keep a cool layer of air next the leaf, while 

 preventing too rapid evaporation, although transpiration is 



