Audubon Republican. [volume] (Audubon, Iowa) 1894-1925, 1908-05-28
PHYSIOLOGY OF TREES.
Some Facts as to Their Life and
Growth.

Roots and leaves are the life or
gans of trees. A large part of the
roots, however, only serve as con
ductors of water and food material.
The young ibrous roots that are COW
cred by fine hairs, are the only ones
which take water and minerals from
the soil. The trunk and branches
simply serve as conductors of food
material between the leaves and roots.
If the fibrous roots are cut off or ex-
posed so that they dry out, the tree
will, in all probability, die.
Some trees, like locusts, willows,
poplars, ETC., have the power of re-
newing their roots readily. Such
trees always transplant easily. There
fore, the first care in transplanting
trees is to keep the ibrous roots from
drying out, and to protect them from
injury during the time which tran
spires before the tree is planted
again.
In growing, trees build up a body
of cell tissues, make foliage, flowers
and fruit.
They take up food material from
the soil and air, changing it into cel-
lulose and various other compounds.
Like all other plants, trees depend
upon moisture, heat and light as the
means of performing their growth.
From the soil trees principally get
water by means of the ibrous roots.
This water is carried to the leaves,
through the trunk and branches, be-
ing partly used for wood formation
on its way and partly given Up to
the air by the leaves.
Minerals are taken only in small
quantities and consist mostly of lime,
potash, magnesia and nitrogen. They
are carried to the leaves where they
combine with part of the water in
food preparation.
The largest amount of water, how
ever, taken up by a tree, transpires,
or in other words, is given to the air
in the form of vapor. So most of the
mineral substance remains In the
leaves, these in urn return it to the
soil, when they are shed and left to
decompose on the ground. This ex-
plains the fertility of soil in timber
land.
But now we must return to what
the tree gets from the air.
The solid portions of a tree, writes
B. Schwering, in Farmers Voice, is
made largely of %cellulose, which con-
sists of carbon with hydrogen and
oxygen. The tree gets it's car
bon by taking carbonic acid from the
air, into the leaves. This, under the
influence of light, air and water, is de-
composed.
Oxygen is thrown out and the re-
naming carbon forms compounds
such as starch, sugar, ETC., by combin-
ing with elements taken from the
water. These compounds, which are
used as food matter, pass downward
through the tree to the very tips
of its roots, making new wood all
along.
This process of food preparation
can be carried on only in the green
parts which are exposed to light and
air. Therefore, the more foliage and
light a tree has, the quicker will it
grow. The leaf and root systems are
both dependent upon each other, for
the roots need the food prepared by
the leaves just as the leaves require
the water sent up by the roots.
A leaf consists Of cells, lying close
ly together and covered by a sack
known al the epidermis. Between the
cells are small spaces known as in
tercellular spaces. The epidermis has
minute openings which open into the
i~ntercellular spaces, allowing the air
and other gases to come in contact
with the cells. These cells take car
bon dioxide and give up oxygen
AS oxygen is the gas which we need
in breathing, and carbon dioxide the
poison which we breathe out, 1t can
readily be seen that every plant or
tree is an important factor in the
health Of plants and animals.