The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1874-09-26 00:00:00

THE FALL OF THE LEAF.

The phenomenon of the 'fall of the leaf," common as
it is, is very difficult to explain satisfactorily. The
following are the facts, so far as we understand them,
which are exceedingly interesting and instructive.
It seems that Nature begins the provision for separa-
tion almost as Boon as the leaf is born in spring.
When first put forth into the atmosphere the stalk of
the leaf, supposing one to be present, is continuous
with the stem. As the leaf and its stem grow, how-
ever, an interruption between the tissues (fibrous and
cellular) occurs at the base of the leaf-stalk, by
means of which a more or less complete articula-
tion or joint is gradually and ultimately formed.
This articulation is produced by the continuation of
the growth of the stem after the leaf has attained its
full growth, which it generally does in a few weeks.
The growth of the leaf being completed, the base of its
petiole, or footstalk, is no longer able to adapt itself to
the increasing diameter of the stem, and a fracture
between that base and the stem necessarily ensues;
the excision advances from without inwards, until it
finally reaches the bundles of woody fibre, which form
the main support of the leaf. While, however, nature
is forming a wound, she is at the same time making
provision to heal it, for the cuticle or epidermis of
the stem is seen to grow over the surface of the
scar, so that when the leaf is detached the tree
does not suffer from the effects of an open wound. The
provision for separation being thus completed, the
leaf is parted from the stem by the growth of the bud
at the base, the force of the wind, or even by its own
weight. Therefore, as soon as the glorious colours of
the autumn leaves begin to fade, this provision for
separation is completed, and the winds Bing their
death-dirge as they carry them away from their sum-
mer's home on the branches of the trees, and scatter
them in countless numbers upon the ground. The
fall of the leaf is, therefore, the result of a regular
vital process, which commences with the first forma-
tion of the leaf, and is only completed when
it is no longer useful to the tree. There is no
denying, however, that the frosts of autumn, by sud-
denly contracting the tissues at the base of the leaf-
stalk, accelerate the fall of the leaves. All must have
noticed, on a frosty morning in autumn, that the
slightest breath of tar moving among the decayed and
dying leaves will bring them in complete showers from
the trees to the ground. The leaves of the beech,
hornbeam, and oak die in autumn, but frequently
remain attached to these trees throughout the winter
months, provided that the trees are not so situated
as to be exposed to violent winds. Such leaves,
when examined, will be found to be continuous with
the stem, and therefore without that articulation or
joint which so naturally assists in the separation
of the leaf from the tree. These dead leaves fall off
when the new leaves are put forth in spring; they
are, in fact, pushed off by the expansion of the stein
when the growth of the season commences. The
leaves of evergreen trees and shrubs, and of coniferous
trees, as the pine awl fir, do not fall in autumn, but in
spring, when the growth of the season is proceeding;
and, as this annual leaf-fall is only partial, consisting
of one-half or one-third at a time, there is always a
sufficient number of leaves left on such trees to keep
them clothed with perpetual verdure. Hence it is
that their foliage consists of leaves which have been
attached to the stem from one to three or five succes-
sive years. —Garden.