by Mark W. LaSalle, Ph.D., Our Mississippi Home
Everyone knows that the bark of trees is the plant’s skin, protecting the tree’s living tissues beneath. What lies beneath bark is also a story of how trees grow and have evolved to become the giants among plants. But bark is also habitat for many organisms that are found nowhere else.
Bark is simply the outer dead tissue of woody plants that forms from the main living layer of plants – the cambium (from Latin meaning exchange). This layer lies just below the bark and between it and the woody tissues that form the bulk of stems and trunks of trees. From this position, the thin cambium layer lays down new tissues in both horizontal and vertical directions – allowing the plant to grown in width and height. A cross section of a tree trunks serves to illustrate the arrangement.
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