Evening capital. (Annapolis, Md.) 1884-1910, 1890-11-11
PRICE ONE CENT.


All trees and plants that spring from
two lohed seeds. that is. from seeds that
| can be split like peas or acorns. have
their leaves veined irregulasly They
can not be torn across except by broken
line On the contrary. the leaves of
such plants as spring from kernel that
will not srlit--a grain of corn, for ex-
ample-can he slit lengthw ise into taper
ing strips In this way we can distin-
guish plants that grow from seeds that
have two cotyledons from those whose
seeds have but single cotyledon.
The leaves of dicotyledonous plants,
as they are called, are of great variety
Of size, shape, texture, and finish. They
are not a single membrane. but are made
up of many layers of cells. The interior
of the leaf communicates with the ex-
ternal air by millions OF little mouths.
These are mostly ON the under surface
OF the leaf This is TO protect them
from the sun, and to secure uniform
evaporation
The surface of the leaf is in some cases
protected by coat of varnish. The
upper side of an oak or a birch leaf will
show this finish plainly. In other cases
the same object is gained by an increased
thickening of the sap In Australia, it
is said, the leaves of some trees TAX
vertical position, SO as TO present :.
smaller surface to the sun. Fleshy
leaves are protected BY their thickness
Another mode OF protection is by the
growth OF woolly hairs Plants of the
desert are frequently covered with felt
of hair. The cac,us often grows in this
way. Some species of plants which are
smooth in the north become woolly in
the south.
The uses of nairs are various. They
serve to check too rapid evaporation.
They protect the breathing holes, and as
these are on the under side of the leaf,
it is the under side that is hairy. This
fact is strikingly noticeable in the case
of the white poplar, for as the leaves Of
this tree are in almost constant motion
the turning from one side to the other
produces shimmering effect
In other cases the use OF the hair Is to
throw off water and prevent the breath
ing holes from becoming clogged as they
would otherwise be with fog or dew.
This is important in some mountain and
marsh plants Nature resorts to the
same contrivance for protection against
too much moisture that she uses against
too little
The hairs also serve to shade the leaf
from excessive light and heat. More
than this, they protect the leaf against
insects, which would otherwise feed
upon it The stinging hairs OF the COM
mon nettle save the plant from being fed
upon by the larger animals. A coarse
woolly hair is equally distasteful The
leaf Of the holly is protected by spines
along It's edges.
Most leaves are glad of as much sum
shine as they can secure, and are ar
ranged with reference TO this end. II
we cut off beech twig below the sixth
leaf, we find that the leaf area which il
carries is about 1S square inchea The
width of the leaf is IL inches. This is
determined by the distance between the
buds. II the leaves were broader, they
would overlap; if they were narrower,
there would be waste of space.
The area on the one hand, and the
width on the other, being thus deter
mined, the length is fixed, because, to
secure an area of 18 inches with 9 leaves
which are about II inches in width, tho
length must be about inches.