CHAPTER IX 



FACTORS INFLUENCING GROWTH 



1. The stems of all trees and of most shrubs grow 

 vertically, straight up out of the ground, while the main 

 root grows in exactly the opposite direction, downwards. 

 This upward tendency of stems and downward tendency 

 of roots is apparent at the very beginning of the plant's 

 life when it emerges from the seed. For, put seeds of 

 Bean or Marrow in all positions in soft earth, and 

 examine them when the first signs of germination 

 appear. The radicle, you will find, is in every case bent 

 downward, and the shoot, though it may be curved at 

 first while passing through the earth, stands straight 

 upright when it is free. 



And again take seeds which have begun to germinate 

 and have half an inch or so of radicle exposed, and put 

 them in various positions, covering them with light soil 

 or moss or sawdust ; then look at them again after a 

 couple of days. You will find that in every case the 

 end of the radicle is bent downwards, and the shoot 

 upwards. 



We may see the same thing in older plants of all 

 kinds. The Palmyra- Date and Coco-nut palms are 

 7 



