LAYING THE FOUNDATION.
"COTYLEDONS, radicle, embryo! Cotyledons, radicle, embryo!" Bennie was
saying these words over to himself, then he added, "The cotyledons are
the seed-leaves, the ones that pop out of the seed after it has lain a
while in the ground. The radicle is the little thing like a stem that
supports the cotyledons, and from the other end of it the root begins
to grow. I know so much, anyway! Then the embryo? Oh! that's the whole
thing curled up in the seed."
"I wonder which mamma will tell us about this morning," said Ella as
she and Tom skipped across the meadow, leaving Mrs. Browne to follow
more leisurely with Bennie.
"The root, of course," said Tom; "the root is—well, it is the root of
the whole thing. The foundation, you know."
"I hate foundations; that is what Miss Lyman is always saying, 'Young
ladies, lay the foundation well!' I thought we would get away from all
that in vacation," and she laughed merrily.
"Well, there can't be a great deal to be said about roots, I am sure,"
returned Tom; "that'll comfort you, I suppose."
When they were all ready Mrs. Browne said:
"I think we will talk about roots to-day." Tom and Ella exchanged
glances at this, but Mrs. Browne continued, "the root has two uses; it
serves to fix and hold the plant firmly in the ground, and also it is
the part of the plant that takes up food from the soil. The plant needs
to be fed with certain minerals and gases, and these are dissolved in
the moisture of the soil, and the water is sucked up by the roots."
[Illustration: FLESHY ROOT.]
"I do not understand," said Ella, "how the root can suck up water! Are
there holes in the root which stand for mouths?"
"The roots are covered with what we call fibrils or root hairs, and
these are very delicate, and through their surfaces they take in the
moisture. Now if you will examine this root of a young tree which Tom
has pulled up for our lesson you will see that the root has branched,
and every year the branches multiply and spread farther and deeper into
the ground. Now notice that the branches grow smaller and smaller.
Look through this microscope and you will see the tiny hair-like
projections; these take up the moisture, and as there are so many of
them upon every little rootlet, they take up a great deal. We call this
a branching root; some roots are what we call fibrous. Tom, suppose you
see if you can find a buttercup root and bring it here."
[Illustration: FIBROUS ROOT.]
Tom sprang to do his mother's bidding, and soon returned with what
looked like a hank of thread—long fibres bound together at the surface
of the ground, at the top of what we call the axis of the plant. Mrs.
Brown explained that the central stem is called the axis, and that the
part which goes downward is the descending axis, and the part that
shoots upward and bears the branches, is the ascending axis.
"You observe," she said, "that in the case of this plant there is
no descending axis, the long fibrous roots spring from the collum
or collar, which is the place where the root and stem join, or from
the line of division between the ascending and descending axis. The
fibrous roots are mainly for the purpose of absorbing nourishment for
the immediate use of the plant, and this structure gives them greater
surface by which to take up the moisture for rapid growth. Other roots
serve an additional purpose. They store up food for the future growth
of the plant, and such roots are called fleshy roots, and many of them
are useful to us for food. In such the axis is long and thick and with
only short branches and of course fewer fibrils."
"Now if we leave one of these fleshy roots—for instance the beet—in the
ground through the winter instead of storing it in the cellar for table
use, when spring comes the plant will begin to put forth a new growth,
much more vigorous than that of the first year, and quite different.
It will send up strong shoots bearing flowers and ripening seed. And
all this will use up the food stored in the root, and when the seed has
ripened the plant will die. This we call a biennial plant."
"The fibrous roots belong largely to annual plants, while the branching
roots belong principally to the woody plants, as trees and shrubs. I
heard Tom talking about transplanting trees. You should take great care
not to injure the small roots and fibrils, for, by breaking or cutting
off these, you lessen the absorbing power of the root."
"You spoke of annuals and another kind—those which live two years,"
began Ella.
"Biennials; be sure you get the names; it is just as well to learn
a thing thoroughly in the beginning—a few facts, names or dates
thoroughly fastened upon the memory are better than a vague idea of a
whole subject, without any definite knowledge. We classify plants as
annuals, biennials and perennials; those which live one year, those
which die after perfecting the seed the second year, and those which
live on year after year."
"Aren't we almost through with roots?" asked Ella.
"I could tell you a great deal about roots, but I suppose you want
to get to leaves and flowers, so we will drop the subject of roots
and take up the stem next time," said Mrs. Browne, smiling upon her
impatient little girl.