
50 FLOWERING PLANTS 
CHAPICR Vil 
THE STEM 
Seriaiies of THE stem of a growing plant consists of meri- 
Growing 
Point. 
stematic and permanent tissues. 
found at the apex of the stem, for this is its 
The former are 
growing point ; they also occur wherever growth in thickness 
7 
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is Ah pe Ae 
HNC 
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Fic. 17.—APEX OF STEM, MepIAN Lonerrupt- 
NAL SECTION. (High power, diagrammatic.) 
d, dermatogen ; 
l, leaves, 
pl, plerome; pr, periblem ; 
is taking place. 
A median. longi- 
tudinal section 
through the grow- 
ing point of a stem 
shows cells, which 
are all somewhat 
similar,- thin. 
walled, and rich 
in __ protoplasm, 
constantly divid- 
ing, and thus 
giving rise to new 
cells. Almost im- 
mediately behind 
the apex these 
cells are seen to 
be arranged in 
three groups or 
tissues : 
1. A central tissue, composed of rather larger cells, with 
thin walls. This is called the plerome. 
2. On each side of this the cells are smaller and in shape 
oblong. This is the periblem. 
3. The external layer consists of more or less square cells, 

