Evening star. [volume] (Washington, D.C.) 1854-1972, 1874-11-07
The Fall of the Leaf.

IRON he LONDON GdrdeR
The phenomenon of the "falI OF the leafD
common AS il is, is very dificult to explain SAT-
istaCtorily. The following are the facts, so far
as we understand them, which are exceedingly
interesting and Instructive. Ii seems that ma
ture begins the provision for separation almost
as soon as the leaf Is born in spring. When first
put forth into the atmosphere the stalk OF the
lear, supposing one to be present, is continuous
with the stem. As the leaf aud its stem grow,
however, an interruption between their tissues
(hbroUs ana cellular) occurs at the base of the
leef-stals, 10y means OF which a more or less
complete articulation or joint ia gradually and
ultimately formed. This articulation Is pro-
duced by the continuation OF the growth of the
stem after the leaf has attained full growth
which 1t generally does in a few weeks. The
growth of the leaf being cOmpleted, the
tase of its petide, or foot stalk. is no longer
able TO adapt itself to the increasing diameter
base and the stem necessarily ensues:
the excision advances from without inward,
until Ii finally reaches the bundles of woody
hber, which form the main SUPPORT of
the leaf. While, however, nature is forming a
wound, she is at the same time making proyi-
sion 10 healit for the cutcle epider mis- 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 CON-
pleted, 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 colors OF the autumn leaves
begin to fade, this provision for separation is
as they carry them away from their summers
nome on the branches OF the trees, and scatter
them in countless numbers upon the ground.
The fall OF the leaf Is, therefore, the result or
regular vital process, which commences with
the first formation OF the leaf ard is only COM
Pleted when IL is no longer useful 20 the tree.
There is no denying, however, hat the frosts of
autumn, by suddenly contracting the tissues at
the base OF the lest-stsIs, accelerate the fall
OF the leaves. All must have noticed, on a
frosty morning in autumn, that the slight
est breath or sir moving among the de-
cayed 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 situ-
sted as TO be exposed to violent winds. Such
leaves, when examined, will be found to be
continuous with the stem, and therefore with
out that articulation or joint which 30 naturally
assists in the separation of the leaf from the
tree. Those dead leaves fall Off when the new
leaves are put forth in spring; they are, in fact
pushed off by the expansion OF the stem when
the growth OF the season commences. The
leaves or evergreen trees and shrubs, and of
coniferous trees, as the pine and FIR do ct 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 time, there is always a suffi-
cient number of leaves left on such trees TO
Keep them clothed with perpetual verdurs
Hence ii Is that their foliage consists of leaves
which have been attached TO the stem from one
to three or i've successive years