The Pioche weekly record. [volume] (Pioche, Nev.) 1877-1900, 1894-02-22
TO TILLERS OF THE SOIL
Hints That May Prove Of Benefit to
Our NelghbOrs'
Articles Of Unduubsd Worth 10 The Farmer Collected
From Reliable Sources,
THE EFFECT OF LICHENS ON
TREES.

was recently read at meeting OF the
State Horticultural Society. 1t relates
to the growth on the bark of trees which
is commonly termed "moss," and is
thus of direct interest to orchardists,
especially in regions near the coast
where this growth is greatest. 1t has
long been question whether the moss
was injurious or not, and Mr.. Holmes
investigation shows that clean trees are
the proper trees to grow:
A New Subject.-The effect OF lichens
on trees is a subject which, we believe,
has never been thoroughly studied. We
have not been able to find more than a
passing remark on the subject in any
of the literature to which we have had
access. The attention OF botanists has
been devoted to the morphology and
physiology of lichens themselves, with
out much reference to their relations to
their hosts. They certainly have not
regarded them in the light OF serious
enemies to the trees on which they live.
They are generally held to be epiphytes,
or air plants, the bark of the tree form
ing the substrate for their support.
Throughout the damper portions OF
California, where the fruit trees be-
come thickly covered with lichens, they
have been regarded by the lruit-growers
labor are expended to clean the trees OF
these foreign growths. 1t is certainly II
fact that trees that are badly overgrown
with lichens are apt to be lacking in
vigor. This, however, is not conclusive
evidence that the lichens are the cause
| of the phenomenon, although it strongly
supports this conclusion. Dead trees
are generally covered more thickly than
live ones, thus showing that the lichens
are not dependent for their support
upon materials that the tree Celebrates.
On comparing the dead twigs with the
live ones on the same tree, the lichens
will be found to be the largest on the
dead twigs. This may be because the
lichens are parasitic and have killed the
twigs or because they are saprophytic
and thrive best on the bark which is
most decayed. Entire parasitism is out
of the question, for the parasite in that
case would die when its host died, but
there is nothing against the supposition
that the lichens are partially parasitic
This would account for less vigor OF the
badly infested trees and the fact that
the lichens continued to live after the
death of their host. Another reason
might be brought forward to account fol
the greater prevalence OF lichens OF
sickly or dead trees. The bark of thrifty
and vigorous trees is generally brighter
and smoother than the bark of sickly
ones, and the spores of lichens woulC
find less chance of attachment. This il
probably the reason why smooth barkeC
trees, like the cherry and apricot are
almost entirely free from lichens, while
the rough barked oaks and soft naples
are often thickly overgrown with them
How Lichens Grow.-The character o
the bark is an important element in de
termining what species of lichens vii
grow upon it. Our common lichens vii
not thrive well on the bark OF pines an(
cedars, though there are some species o
lichens which are peculiar to those trees
There are lichens which grow upoi
moses, and there are others which ar,
peculiar to other species of lichens
These facts point strongly to the con
clusion that lichens derive their support
in part at least, from their substrate.
further argument in the same direction
is the fact that lichens often contain
large percentage OF mineral matter. TIL,
only other source of the mineral con
stituents beside the bark is the dus
which always collects more or les
around their base; it seems more pro
bable that the minerals were derived
from the bark than from this source.
The Method of Investigation.-Th
foregoing facts are not conclusiv,
evidence of the injurious effect o
lichens on trees. In order to gain furthe
light upon the subject we began stud,
of the method of attchment of the lichel
to the bark. The bark used was that o
the soft maple, which was overgrowl
with faliaceous lichen, Rdmalint
MeEzwSSii. Sections were cut through
the paint of attachment of bark ant
lichen, and examined by the microscope
for evidences OF local injury. In orde
to trace the course of the mycelium o
the lichen, we tried several methods o
double staining. Decidedly the bes
results were obtained with the anilin
colors. About the only other stain tina
we found of service was acetic acit
carmine. Sections were left in a stron,
solution for "a hours and then slight,
decolorized. The mycelium was tinget
red, the cork cells remaining unstained
The action of the cork toward the anilin,
stains was peculiar sand quite decided
We found that several of the stains
would color it quite strongly and leav,
the Echen almost uncolored; other
again would stain the lichen and no
tinge the cork cells; others, as Bismarck
brown, would stain both bark and licher
uniformly. Picronigrosin stains tn,
mycelium very dark blue and the corl
yellow. Aniline green colors the corl
cells bright green and the myceliun