Roots do their work underground as a rule.
[Illustration: [Roots]]
You might prefer not to be a root, if you had your choice; you might
prefer to be a leaf or a flower.
I have never heard that the roots complained of their work, however. For
one thing, it is easier. All they have to do is to hold the plant fast,
suck up juices from the earth, and in some cases store away food
material,—that is, if they are regular, well-behaved, everyday,
underground roots.
Sometimes, however, roots come out of the ground and do all sorts of
things,—cling to walls and hang in the air and perform in other
unroot-like ways; but these are not what we are talking about. We are
talking of roots, such as those of the morning-glory and nasturtium and
geranium, which stay underground and behave themselves.
Since it is dark where they live, they have no chlorophyll grains, and
do not have to make starch. They merely use up the starch that comes to
them from above.
Since they are not blown about by the wind, they do not need
complicated, stiff, supporting tissues like tree trunks. On the whole,
they are rather a simple people. They are made of cells, of course. But
there are not so many kinds of cells in them as in the stems and leaves.
They have skin cells, but no pores. Out of their skin cells grow their
most interesting and important parts. These are called root hairs. They
are made of cells lying next each other, like other hairs, but they do
all the sucking up of food materials for the whole root. These root
hairs draw the water and other food out of the soil for the use of the
plant, and the rest of the root only stores it up and conducts it to the
stem and leaves above and anchors the plant to the ground.
The root’s work as an anchor is important, as you can imagine.
Just suppose that plants had no strong roots twisting around stones and
bits of earth underground and holding them fast! What a time there would
be whenever the wind blew.
Even a light breeze would be worse than a cyclone at present, for it
would send the wheat in the wheatfields flying before it.
All the plants would go hurry-skurry wherever the wind blew—excepting
the morning-glories and others that were twined about trellises or
fences or rocks; and even they would be blown all out of shape.
And when a strong wind came, if the trees had no roots to anchor them
_they_ would go hurry-skurry in the direction in which the wind blew,
even if they were balanced so that they could not fall over; and we
should see the forests sliding about the country and probably right on
our houses, knocking them down, so we would not be able to have any
houses, but would have to live in caves. It is a very good thing for us
that the plants are held fast by their roots.
Well, the root hairs do the most important work of the plant after all.
It is they who go poking their noses through the soil, and with their
cells draw up water and potash and nitrogen and sulphur and iron and
many other things which have become dissolved in the water. They are
even able to dissolve rocks and such delicacies for themselves.
Now a growing root tip is a very delicate thing. You could not expect it
to go pushing its tender tip through the hard earth without some kind of
protection. And it does not: it wears a cap. This cap fits over the tip
of the root and is hard. The cap is not alive, that is, the outside of
it is not. The growing part of the root tip is just behind the cap.
The root tip grows by adding on new cells and so pushes the root cap
ahead of it. The hard root cap finds its way between the particles of
earth and so opens a channel for the growing root tip behind it.
The cap wears off on the outside as the bark does on a tree, and, like
that, is continually renewed from the inside where the cells are alive.
[Illustration: Root hairs. Root cap.]