“CHAPTER V 
- STEMS 
76. What the Stem is. — The work of taking in the raw 
materials which the plant makes into its own food is done 
mainly by the roots and the leaves. These raw materials 
are taken from earth, from water, and from the air (see 
Chapter XI). The stem is that part or organ of the plant 
which serves to bring roots and leaves into communication 
with each other. In most flowering plants the stem also 
serves the important purpose of lifting the leaves up into 
the sunlight, where alone they best can do their special 
work. 
The student has already, in Chapter III, learned some- 
thing of the development of the stem and the seedling ; 
he has now to study the external appearance and internal 
structure of the mature stem. Much in regard to this 
structure can conveniently be learned from the examina- 
tion of twigs and branches of our common forest trees in 
their winter condition. 
77. The Horse-Chestnut Twig.! — Procure a twig of horse-chest- 
nut eighteen inches or more in length. Make a careful sketch of it, - 
trying to bring out the following points: 
(1) The general character of the bark. 
1 Where the buckeye is more readily obtained it will do very well. Hick- 
ory twigs answer the same purpose, and the latter is a more typical form, 
having alternate buds. The magnolia or the tulip tree will do. The student 
should (sooner or later) examine at least one opposite- and one alternate-leaved 
twig. 
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