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!
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]
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
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
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
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!
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By The Editors of Encyclopaedia Britannica Article History
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bark, in woody plants, tissues external to the vascular cambium [the growth layer of the vascular cylinder]; the term bark is also employed more popularly to refer to all tissues outside the wood. The inner soft bark, or bast, is produced by the vascular cambium; it consists of secondary phloem tissue whose innermost layer conveys food from the leaves to the rest of the plant. The outer bark, which is mostly dead tissue, is the product of the cork cambium [phellogen]. Layered outer bark, containing cork and old, dead phloem, is known as rhytidome. The dead cork cells are lined with suberin, a fatty substance that makes them highly impermeable to gases and water. Gas exchange between the inner tissues of bark-covered roots and stems and their surroundings takes place through spongy areas [lenticels] in the cork.
Bark is usually thinner than the woody part of the stem or root. Both inner bark [secondary phloem] and wood [secondary xylem] are generated by the vascular cambium layer of cells: bark toward the outside where the oldest layers may slough off, and wood toward the inside where it accumulates as dead tissue.