The Stem. 74 
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 (Fig. 33). The nodes are 
centers of vital activity, and are 
the points at which lateral grow- 
ing points (buds, (128)} are nor- 
mally formed, and whence roots 
usually start first in cuttings and 
layers (358, 349). 
117. The Stem Lengthens 
by the Elongation of the Inter- 
nodes, as well as by the formation 
of new ones. As the internodes 
soon attain their ultimate length, fe Mee Acari 
it follows that the stem lengthens _ box elder, Negunio aceroides. B, 
of the wild grape, Vivis riparia. 
only near its distal end. Au inter- 
node that has once ceased elongating does not afterward 
resume it, hence the internodes of perennial plants that are 
only partially elongated at the close of the 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 perceptible ring 
about the shoot, which enables us to readily locate the point 
at which growth started in spring (Fig. 34), and we can often 
determine the amount of growth that took place during the 
preceding season or even farther back. 
