HOW A TREE GROWS
Trunk
The trunk of a tree is the the part that's above ground before the branches start.
Underneath the bark, there is a thin layer of cells called the cambium (pronounced "cam-bee-um"). The cambium cells divide and make new wood on the inside and new inner bark on the outside. In this way, a tree gets bigger around as it grows! A tree needs to get w i d e r a r o u n d as it grows. As a tree gets bigger, it needs more and more support to keep it from falling. The large tree trunk is what keeps the tree from falling! Below is a photograph of a tree trunk unwrapped. You can click on the picture to see the full-sized image. Can you identify the inner bark, the cambium, and the wood?
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