THE WALLFLOWER 17 



join on to each other, and themselves give off in- 

 numerable lesser branches, which permeate every part 

 of the leaf, and are united among themselves into a 

 fine network The finest branches of all, however, 

 end blindly within the meshes of the network. The 

 smaller veins can only be .traced with the help of 

 a lens (see below, p. 65, Tig. 24). 



We have now described the chief external characters 

 of the stem and leaves. To complete our sketch of 

 the vegetative organs, we will next consider the root. 



b. The Root 



If we pull up a Wallflower and wash away the 

 earth which clings to the root, we find that this, like 

 the stem, has a main axis, which grows straight 

 downwards, in the same line with the erect axis of the 

 stem. A main root of this kind is called a tap-root. 

 -Of course the root meets with more resistance to 

 its growth than a stem does, and sometimes it is 

 forced to diverge more or less from its vertically down- 

 ward direction (see Fig. 1). From the tap-root a number 

 of branches are given off. These branches do not grow 

 straight down, but take an obliquely descending course, 

 forming an angle a little less than a right angle with 

 the tap-root. From these principal branches other 

 much smaller ones arise, and these also ramify 

 repeatedly. The finer branches of the root do not 

 take a fixed course, but penetrate the soil in all 

 directions equally. If the plant has been very care- 

 fully taken up, we shall find that particles of earth 

 stick firmly to the very youngest branches of the root 



