THE STEM OF 

__ be progressively longer toward the base of the stem. Near the 
_ tip of a growing stem (Figs. 15, 91) the leaves are very minute, 
while toward the lower part of the stem they are progressively 
larger until they reach mature size. The internodes near the tip 
are also very short, but away from the tip they become progres- 
sively longer until they also assume a definite length. The 
explanation of this is that new leaves and internodes are formed 






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Fig. 92. Section through apex of the stem of a water plant 
Left, through whole bud (x 60) ; right, through apex only (x 400) 
at the tip, and that they soon reach their mature length and then 
show no further growth in length. Growth at the tip of an organ 
is called apical growth. . 
The apical growth of a stem is due to the activity of a few 
actively dividing cells which are found at the very tip of 
the stem. This part of the stem is hidden by the young leaves 
produced near the tip, and cannot be seen until these leaves 
are removed (Fig. 92). A group of actively dividing cells is 
called meristem. 
Intercalary growth. In addition to apical growth some plants 
have another type of growth known as intercalary growth. ‘This 
type of growth is very prominent in the stems of grasses, In 
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