The Richmond palladium and sun-telegram. [volume] (Richmond, Ind.) 1907-1939, 1912-03-18
THE LIFE OF THE CITY TREES
~ PROF. J. F.rHoMpsoN.

! ~ PROF. ). r. THOMPSON.
1t 10 generally known, think, that
plants are classified. AZ to the length
of time they live into three kinds;
Wis, Annals, biennials and peren-
malls. This is convenient, although,
insofar as the life Of q plant is con-
cerned, one kind is a perennial or
lives rs long as another. Common field
wheat, which is a good example Of
an annual, lives as long as An oak.
good example OF n perennial, and the
oak is as annual as the wheat. The
difference is more apparent than real.
| If we plant a grain of wheat in the
spring. 1t will sprout. grow rapidly.
flower and produce seed before winter
comes on. The stalk. roots and leaves
become lifeless, but the seeds remain
alive. The life of the whole plant has
been concentrated in the seeds. and
each seed contains a little plant, which
II planted. the next season will grow
the one that apparently died last year,
and this may go on year after year
and the life of the wheat may thus con-
tinue like the oak for centuries.
! Plants like people get into a way of
doing things. and as two people may
each have a way of doing the same
things but arrive at the same result.
| SO two plants may arrive at the same
result but in a different way. This
habit of reducing its whole living mat
ter to the limits Of the seed is the way
the wheat and all such plants have OF
| getting through the winter season of
! the year. The life of the plant ia not
only thus continued from year to year
but the individual plants are many
times multiplied.
The plants we call biennials are
slower in reaching their seed time or
the time when the reproduction of the
individual takes place. A plant like the
common thistle requires two years be-
fore it can reproduce others of it's
kind. The first year the seed sprouts
and very short stem is formed with
a mat of leaves which lies flat on the
ground, and during the first year of
it's life it manufactures more food
than it needs for that season and
year 1t sends up stalk and by means
Of the food it stored away the year
before, it is able to flower and pro-
duce seed into which it concentrates
its entire living substance and then
withers away. 1t accomplished just
what the wheat accomplished, but it
got through one winter in the tissues
of root under ground, and we'll pro-
tected leaves, but before the second
winter came it not only had concen-
trated it's living matter in it's seed, but
had learned how to pass one winter in
plant tissues.
Perennial plants like the trees are
very slow in reaching the time when
! they can produce seed. The oak, for
example, does not begin to produce
seed until 1t is about seventy years
old, the beech at about sixty years,
the elm and naples at about forty
years. Therefore these plants have
had to learn how to bridge over win
ter in their tissues also, and by the
time they have bridged over from for
ty to seventy winters in this way they
have learned how. but in that length
of time they have become SO large and
contain so much living matter that it
would be almost physically impossible
to reduce themselves to seeds like the
ANIMALS or biennials and even if they
could, the result would be more seeds
than could be scattered and there
fore useless waste.
During this forty or seventy years.
h0x he,
bear seed, and when they are ready.
they bear seeds for centuries. They
have learned how to adapt themselves
to summer and winter. storm and sun,
dry seasons and wet and we call them
perennial.
In our first article we tried to show
that in all the essentials of life, trees
are not SO very much unlike other liv-
ing things, but a tree is not alive in
all of its parts as animals are. An ami
NAL is alive through and through,
while tree is not. That portion of
tree which we call heart wood is dead
or rather it has no living matter in
it. That portion which we call sap
wood is alive. In most instances the
two may be easily distinguished by the
color. The heart wood is usually
darker than the sap wood. Besides the
sap wood, the bark or bast wood is
alive. What We usually call the bark
is not real bark but a sort of epidermis
which covers the real bark Then be-
tween the bast or true bark and the
sap wood there is a layer of living
cells called the Cambium layer This
layer is made up of real living, work
ing plant-matter. Every year this
Cambium layer of cells adds a ring Of
wood to the heart Of the tree as well
as forms a new bark. and every year
therefore, the lifeless heart wood in
creases in diameter. This zone of liv-
ing matter in a tree behaves much
like the Chambered Nautilus. Every
time it builds a new place in which to
dwell it abandons the old, and this
abandoned chamber in the tree is the