The Stem. 



79 



consists of one or more leaves, attached to the distal* end 

 of a portion of the stem. The part of the stem to which 

 the leaf or leaves are attached is called a node and the 

 part below the node, or in the stem as a whole, the part 

 between the nodes, is called an internode. 



The nodes are distinctly marked 

 in the younger stems of most plants 

 by a slight enlargement or by leaf- 

 scars, if the leaves have fallen (Pig. 

 35). The nodes are centers of vital 

 activity and are the points at which 

 lateral growing points (buds (128)) 

 are normally formed, and whence 



N— 



. j^ roots usually start first in cuttings 

 and layers (358, 349). 



117. The Stem Lengthens by Elon- 

 gation of the Internodes, as well as 

 by the formation of new ones. As 

 the internodes soon attain their ulti- 

 mate length, it follows that the stem 

 lengthens only near its distal end. 

 An internode that has once ceased 



Fig. 35. Nodes (N); A, of 



the box elder, sTegundo acer- elongating docs iiot Usually resume 

 B, of the wild grape, it, hence the internodes of peren- 

 nial plants that are only partially 



Vitis riparia. 



elongated at the close of the 



in general 



growing season 

 remain undeveloped. When growth is resumed in spring, 

 the formation of a comparatively long internode beyond 

 the very short ones of autumn usually forms a percepti- 

 ble ring about the shoot, which enables us to readily 



* Distal means farthest from the point of origin, i. e., the point at which 

 growth started. It is opposed to proximal, which means nearest the point 

 of origin. 



