CHAPTER IX 
STEMS 
Characteristic Features and Types of Stems 
The stem, usually consisting of trunk and branches, is the fun- 
damental part of the shoot. Upon the stem the other structures 
of the shoot, such as leaves, flowers, and fruit, depend for their 
support in the air and sunlight — the position most favorable for 
leaf-activity, pollination, and scattering of seed and fruit. 
Roots, stems, and leaves are intimately related in their activi- 
ties, and the efficiency of one affects the efficiency of the others. 
The productivity of most of the cultivated plants depends not 
only upon a good root system, but also upon a good stem system. 
In some plants, such as Beets, Turnips, Radishes, Lettuce, and a 
few others which have very short stems during much of their life, 
not so much importance is attached to the stem, but even these 
plants, in order to complete their life cycle, must eventually 
develop stems upon which to bear flowers and seeds. Among 
such plants as the trees and grains, the stem is very important. 
The value of a tree for shade, lumber, or fruit depends largely 
upon the character of the stem. Likewise, a Corn or Wheat plant 
with a well developed stem is able to produce larger ears or a 
better head than a plant with a stem poorly developed. 
In comparing stems with roots the following things may be 
stated. First, stems bear leaves and flowers, while roots do not. 
Second, stems are divided into nodes and internodes but roots are 
not. Third, stems branch at the nodes, while in roots branches 
arise anywhere. Fourth, in stems pith is nearly always present, 
while in roots it is usually absent. 
The nodes are the narrow zones, often more or less swollen, at 
which the leaves and buds as well as the branches arise. The 
internodes are the zones between the nodes. The division of the 
stem into nodes and internodes is quite noticeable in the stems of 
Corn and other Grasses, where the nodes divide the stem into 
distinct segments. By the elongation of the internodes, the 
166 
