How knowledgeable are you when it comes to the anatomy of a tree?  Being able to identify parts of a tree is helpful in identifying tree illnesses and safety hazards.  Tweet your tree anatomy questions at us: “@westchestertree”.

Starting from the Bottom:  The Root System

A healthy root system makes for a healthy tree!  The purpose of the tree’s root system is to anchor the tree, as well as absorb water and minerals from the soil.  There are two kinds of roots, large perennial roots and small, short-lived “feeder” roots.

Did You Know:  Tree roots are typically found in the top three feet of soil.

The Five Parts of a Tree Trunk

Did you know a tree trunk has five parts?  A tree trunk is comprised of the outer bark, the inner bark, the cambium cell layer, sapwood and heartwood!  

The heartwood is the innermost layer of the tree trunk, and acts as the supporting pillar of the tree.  Though the heartwood is technically dead, it does not decay or lose strength while the outer layers of the tree are intact.  Heartwood is a composite of hollow, needlelike cellulose fibers which are bound together by a chemical-like glue, lignin, making it almost as strong as steel.

The layer which covers the heartwood is the sapwood, which later hardens and turns into heartwood.  Sapwood acts as the trees pipeline for water, helping it move up to the tree’s leaves.

After the sapwood is the cambium cell layer.  The cambium cell layer annually produces new barn and wood in response to auxins, the hormones which are passed down through the tree.  Auxins stimulate growth in cells and are produced by leaf buds at the ends of a tree’s branches.

Next is the Phloem, or the inner bark, which acts as the pipeline for food.  The Phloem only lives for a short time before turning to cork; this cork is part of the tree’s protective outer bark.

Lastly is the outer bark, which protects the tree from the outside world.  This outermost later helps keep out moisture and prevents the tree from losing moisture; the outer bark also insulates against extreme temperatures.

Branches, Twigs and Leaves

A tree’s branches and twigs spring out of the trunk and are the supportive structure for leaves, flowers and fruit.  Through the process of photosynthesis, leaves make food for the tree and release oxygen into the air.