What lies beneath: Anatomy of redwoods

Discover what’s under the bark

An illustration showing the layers beneath the bark of a redwood tree: phloem, cambium, sapwood, and heartwood.
The layers beneath the bark of coast redwoods and giant sequoias.

Under the bark of coast redwoods and giant sequoias are many layers, each with an important job in the growth and protection of the tree.

Bark – the outer layer of the tree, the bark, protects the tree from damage and disease. Coast redwood and giant sequoia bark is rich in a chemical called tannic acid, which insects and fungus avoid. The thick bark also protects the inner wood from fires.

Phloem – just below the bark is the phloem layer. The phloem carries the food, mostly sugar, from the leaves to the rest of the tree. That is where you find sap (water with sugars and nutrients).

Cambium – moving inward, the cambium is just below the phloem layer. This very thin layer is where new wood is made. When the cambium gets damaged, the tree’s growth stops or slows down.

Sapwood – this layer is also called the xylem. The sapwood is between the cambium and heartwood. It carries water from the roots to the rest of the tree. Old sapwood turns into heartwood over time.

Heartwood – the darker wood at the center of the tree is the heartwood. It keeps the tree tall and strong, giving support. The heartwood also stores water.

Roots – The roots take in water and nutrients from the soil. They grow long distances from the tree trunk but rarely grow deep. They have a special partnership with a fungus, which grows on the roots and helps the tree absorb nutrients.

About the author

Since 1918, Save the Redwoods League has protected and restored redwood forests and connected people with their peace and beauty so these wonders of the natural world flourish.

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