The 5 Layers of a Tree Trunk

Understanding how to properly care for the trees on your property begins with knowing about the anatomy of a tree.  We’re going to walk you through the 5 layers of a tree trunk!

Anatomy of a Tree Westchester Tree Life

The Outer Bark

The outermost later of a tree trunk is the outer bark.  This insulating layer protects the tree’s innermost layers from cold while defending against insects.  A tree’s bark also maintains the tree’s moisture balance; it does this by keeping out unneeded moisture during rainstorms while holding onto moisture during drier seasons.

Inner Bark (Phloem)

Phloem Westchester Tree Life

The second later after the outer bark is the inner bark also known as the Phloem.  This layer serves as the pipeline through which food is passed.  The tree’s Phloem lives for a short period of time before it dies and turns into cork, becoming another layer to protect the tree.

The Cambium Cell Layer

Cambium Tree Westchester Tree Life

The green part of this tree’s branch is the Cambium layer.

The growing part of a tree trunk is the Cambium Cell Layer, which new bark and new wood annually in response to the tree’s hormones.  These hormones, also known as Auxins” stimulate growth in the tree’s cells, and are produced by the leaf buds at the ends of the branches during the spring.

Sapwood

Anatomy of a Tree Trunk Westchester Tree Life

Sapwood acts as the tree’s pipeline for moving water up to the leaves.  A tree’s sapwood is new wood; as new layers of sapwood are produced, the inner cells lose their vitality and become heartwood.

Heartwood

Tree Anatomy Westchester Tree Life

Heartwood lies at the center of the tree; it is the central pillar supporting the tree.  Heartwood is a composite of hollow, needle-like fibers bound by the tree’s natural chemical glue, lignin.  Although heartwood is as strong as steel, it is in fact dead.

Is your tree in need of professional inspection or care?  Call Westchester, New York’s best tree care professionals, Westchester Tree Life at (914) 238-0069 or visit us online at westchestertreelife.com!

 

One thought on “The 5 Layers of a Tree Trunk

  1. Susanna Heinze

    This article was so nicely done! You managed to link some of the nursery terminology with science class terminology (Inner Bark = Phloem; sapwood = new wood/xylem; old wood = heartwood). Whoever wrote this article is a very good teacher. Thank you!

    Reply

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