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What is tree bark? |
Plants
You’ve probably noticed that the stems of many plants are green and smooth. But what about the stems of woody plants? For example, why are tree trunks brown, bumpy, and hard? This is because the trunk, branches, and roots of a tree are covered with bark! Tree bark is the outer tissue of the tree.
Did you know there are two kinds of tree bark?! The inner bark is soft bark that helps transport food from the leaves to the rest of the tree. It is made of tissue called phloem. When phloem dies, it becomes part of the outer bark. The outer bark, also known as rhytidome, is made mostly of dead tissue.
Why do trees need bark? For one thing, bark is like armor for trees and protects them from damage by creatures, and from organisms that can make the tree sick. Bark also protects trees from severe heat and cold, as well as from harsh sunlight. Bark even helps prevent water loss from the tree!
As a tree grows thicker, the outer bark becomes too tight, much
like a coat you’ve outgrown! The outer bark then splits, creating the
cracks and patterns that give a tree trunk its texture. Many items we
use come from bark, including cinnamon, dye, mulch, and medicine.
Is
all tree bark the same? Absolutely not! Bark comes in a variety of
shades, from brown or black to gray or silvery white. Some bark is
spiny, while other bark is smooth, scaly, or covered with ridges. It
can be fun to learn how to identify trees by their bark, or simply to
observe the colors and textures of the bark that covers the trees in our
yards!
Create a tree bark rubbing! Use tape to secure a piece of white
typing paper to the side of a tree trunk. Make sure the paper is
fastened well! Now peel the paper off the outside of a crayon in the
color of your choice. Hold the crayon so it is sideways and the entire
length moves up and down with your hand. This will allow you to get as
much color and texture as possible.
Now rub
the crayon over a section of the tree! Do you notice how the bumps in
the bark are appearing on the paper? This type of art is called a
rubbing! When you’ve finished, you may even choose to cut out a tree
trunk shape from the decorated paper, then glue it to another piece of
paper and add your own leaves. The bark of the tree in your picture will
look like the bark of the real tree you used for the rubbing!
