Fig. 74. — Acacia ^nelanoxylon. 



CHAPTER VI. 



Hitherto I have dealt with plants in which one 

 main consideration appears to be the securing as 

 much light and air as possible. Our English trees 

 may be said as a general rule to be glad of as much 

 sun as they can get. But a glance at any shrubberj 

 is sufficient to show that we cannot explain all leaves 

 in this manner, and in tropical countries some plants 

 at any rate find the sun too much for them. I 

 will presently return to the consideration of other 

 characteristics of tropical vegetation. In illustration, 

 however, of the present point, perhaps the clearest 

 evidence is afforded by some Australian species, 

 especially the Eucalypti and Acacias. Here the 

 adaptations which we meet with are directed, not 

 to the courting, but to the avoidance, of light. 



