Why Do Trees Have "Bark"?

Imagine your tree is wearing a giant, thick coat to keep warm and dry. This coat is called bark. It starts off smooth when the tree is a baby but gets rougher as it grows older. The bark acts like armor, stopping bugs from eating the tasty parts inside and keeping water locked in so the tree does not get thirsty. When you see pieces of bark falling off, think of it as the tree shedding its old winter coat for a new one.

Why It Cracks

As the tree gets wider, the bark has to stretch. Sometimes it cannot stretch enough, so it cracks open like mud in a drought. These cracks give the tree room to grow without bursting.

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Examples

  1. A child rubbing their hand over a rough oak tree feels the deep cracks.
  2. Peeling bark from a birch tree reveals the smooth white layer underneath.
  3. Rain sliding off the waxy surface of a leaf and landing on the bumpy bark.

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