on ft. Leaves or needles
grow on the twigs. But something really important is missing from this
description: the roots. They're the first part of a tree to grow.
AS SOON AS A SEED SPROUTS, a small root tip grows
down into the ground. It feels its way around to find
the best place to keep growing. (Roots like soft, loose,
damp soil the best.)
The
root spreads out and divides.
As the root divides, it grows fine hairs along its
length that increase its surface area so it can suck up
more water from the
soil.
These hairs dry out very
easily—that's why if
you
bring
a
baby tree home from
the nursery to plant
in
your
yard,
you have to be very
careful
not
to expose the roots to air for more
than
five
to ten minutes.
If the
roots are bare and not covered
in
soil,
the best thing is to wrap
a
plastic bag around
them until the hole for the tree is dug and you're
ready to plant it.
A
tree needs healthy roots if it is to
grow tall and strong.
Those cottony fungal threads I mentioned earlier
don't just grow around the root tips—they grow right
into the roots. This doesn't hurt the tree, though. In
fact, it's nice for the tree because it knows the fungi
are helping it. Not only do the fungi help the tree
suck up water, they also guide the roots through the
ground and show them the best places to grow.
*
As
a
tree gets older, its trunk gets wider. Its roots do,
too,
and they become as stiff and hard as branches.
They need to be, because now they must support the
weight of
a
heavy trunk and
a
large crown.
As long
as
there's no
wind,
that's not too difficult.
On a
calm
day,
the tree stands tall on its roots the way
You can see the fine coots on this toppled tree.
They help the tree find water underground.
you stand on your own two feet. It's easy as long as
the trunk is growing nice and straight.
Some trees, though, are quite crooked. And
because they're so heavy, they can easily topple over.
That's why the roots of
a
crooked tree quickly grow
thicker near the trunk so they can support it. It's like
when you spread your feet apart
a
bit to get better
balance. That's what the tree does, too.
Whenever a storm blows, the wind tears hard at
any tree in its way. Imagine the force of fifty cars
trying to push the tree over. It can only survive if it
has strong roots, which hold the tree down like thick
ropes holding down a big tent. Except roots can
withstand much more pressure,
If you find
a
tree that has fallen over in the forest,
take a look at its roots. If the tree is a spruce or a
Douglas fir, the roots will often be spread out in the
shape of a large, flat plate. No wonder the tree fell
over—to provide firm support, roots must grow deep
down into the ground.
Sometimes a tree stump will show you just how
important the roots
are.
In
fact,
they're the most import-
ant part of the tree, Why? Because often a shoot will
grow out of
an
old stump, and this shoot
can
grow up
to be
an
adult
tree.
It's really the
same
tree,
except now
it has
a
whole new trunk.
Roots may be very strong, but they're also sensi-
tive.
They really don't like it when people walk on
them or, even worse, when cars drive over them.
They may get squashed and even injured. Diseases
could get into their wounds and spread through
their trunks. Then the tree will die before it has
a chance to grow old.
SOME TREE ROOTS ARE GIGANTIC. The roots of
the Moreton Boy fig are so enormous you
could
easily play hide-and-seek
in
them. These
enormous roots support enormous crowns: the
branches
can spread
out