132 AGRICULTURAL BOTANY 



Although their stems above ground may be cut off and 

 seeding time prevented, the spread of the plant is not 

 hindered, for the underground stems still grow, plow- 

 ing or chopping off the stems serving merely to make a 

 bad matter worse by increasing the 

 ,v number of separate plants. Under- 



ground stems of this kind are called 

 rootstalks. 



Nodes. Stems are made up of 

 successive joints, or lengths. At the 

 point where one joint, or section, 

 ^ joins another there is an enlargement 

 of the stem. This, the point where 

 the leaf is often attached, is called 

 a node. The section of stem between 

 two nodes is called an internode. 



If the leaves have fallen, the nodes 

 can be plainly seen by the leaf scars 



FIG. 56. Stems of Box \ J J 



Elder (/i) and wild or by the slight enlargement of the 



Grape (B) ; N, Nodes. stem 



Stems and their branches grow by adding sections, or 

 joints, and also by lengthening their internodes. 



The internodes of the main stem are longer than those 

 of the branches. The internodes of only the newer parts 

 of woody plants lengthen. If an internode ceases to 

 lengthen during any growing season, it will not usually 

 resume growth, but will remain fixed at that length. 

 When an internode grows rapidly, it usually grows to a 

 considerable length, the length and also the diameter 

 depending upon the rapidity of growth. As might be 

 expected, growth is much more rapid in the spring 

 than in the fall. We may often distinguish the long 

 internodes of spring following the short ones of autumn. 



