Plant Defences 



115 



they are really closely related. Their flowers and fruit shows 

 the relationship also, so their book name is the same, Acacia. 

 The thorn tree of the Karroo is Acacia horrida, Willd. ; Acacia 

 melanoxylon, R. Br., is an Australian cousin (black-wood). 



Notice the bushes and trees about your district. Are their 

 edges or their flat surfaces turned toward the sun ? The slender 

 green branches of the beef- wood tree {Casuarina) take the 



Fig. 102. — A nosegay from the Karroo. 



place of leaves. This tree also comes from the " land of 

 shadowless forests ". 



At noon we spread rugs over the Karroo thorn trees when 

 we sit under them for shade. Place the tin of little Karroo 

 trees in bright sunlight. How do they protect themselves ? 



Anacampseros papyracea, E. M., known in the Karroo as the 

 "yeast plant," has large papery stipules which completely 

 cover small fleshy green leaves. Their cells absorb rain and 



