How Plants Live 27 
materials they need, (3) what they take out of the air, 
what they give off into the air, and how they do this, 
(4) what advantage they have in being green, (5) how 
they may be protected from their enemies, and (6) how 
they may be grown to yield especially early crops or 
crops of unusually fine quality. 
This knowledge of how plants live and grow has now 
become a science, and an understanding of this science 
is of the greatest help to the gardener in his work. For 
knowing how plants live makes it more interesting to 
work with them, and the scientific gardener can care 
for his crops far more intelligently and supply their 
needs far better than one who does not understand the 
reasons for what he does. In the following para- 
graphs, therefore, we shall explain how a plant lives. 
The parts of a plant. Let us examine some garden 
plant, such as a bean or a corn plant. We notice that 
‘it is composed of a stem and leaves which grow upward 
into the air, and of roots that are in the soil. 
Now let us look at a young radish about ready for 
table use. At first glance its leaves appear to grow 
directly from the roots. But careful examination shows 
that there is really a short stem between the leaves and 
the main root; and when the plant shoots up into 
flower, we see that it has the same parts as the bean 
and corn and other plants that we grow in our gardens. 
Much as garden plants differ in form and appearance, 
they are all alike in having (1) Jeaves that are exposed 
to the air and sunshine, (2) roots that burrow in the earth 
and darkness, and (3) a stem connecting the roots with 
the leaves. 
