designed, not only to support the plant by fixing it in the soil, but
also to fulfil the functions of a channel for the conveyance of
nourishment: it is therefore furnished with pores, or spongioles, as
they are called, from their resemblance to a sponge, to suck up whatever
comes within its reach. It is found in a variety of forms, and hence its
adaptation to a great diversity of soils and circumstances. We have
heard of a willow-tree being dug up and its head planted where its roots
were, and these suffered to spread out in the air like naked branches.
In course of time, the roots became branches, and the branches roots, or
rather, roots rose from the branches beneath the ground, and branches
shot from the roots above. Some roots last one year, others two, and
others, like the shrubs and trees which they produce, have an indefinite
period of existence; but they all consist of a collection of fibres,
composed of vascular and cellular tissue, without tracheae, or
breathing-vessels. The stem is the grand distributor of the nourishment
taken up by the roots, to the several parts of the plant. The seat of
its vitality is said to be in the point or spot called the neck, which
separates the stem from the root. If the root of a young plant be cut
off, it will shoot out afresh; if even the stem be taken away, it will
be renewed; but if this part be injured, the plant will assuredly die.