Page 13 - The Tree Book

Underground roots
One of the most important parts
of a tree is actually the part hidden underground. Underneath the tree trunk, there is a network of roots which soak up water from the soil, just like drinking straws. The water contains minerals that the tree needs to stay healthy.
Roots also keep the tree steady in the ground, so it won’t blow over if it’s very windy. Trees often have a root called a tap root that goes straight down to keep the tree stable.
1. Tap root
2. Root
3. Rootlet
4. Top soil
5. Subsoil
6. Rocky layer
Water in the soil
Tiny rootlet hairs soaking up water
Pollution
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Large roots divide like branches into smaller roots, which divide again into even smaller roots called rootlets. These roots grow sideways to search for water. Each tiny rootlet is covered in little hairs that sense water in the soil. If they sense pollution, then they can start growing in another direction!
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