secondarygrowth213-page5

secondarygrowth213-page5 - patterns in bark. The bark...

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Secondary Growth in Stems: Wood, Bark and Surface Features - 5 Secondary dermal tissue is produced from the cork cambium, which produces cork tissue and cork parenchyma cells. The tissues produced by the cork cambium are collectively called the periderm . As the original epidermis and cortex layers are destroyed and sloughed off, they are replaced by cork. Primary phloem will also be replaced with the expansion in girth as the plant grows. Cork tissue interlaces with secondary phloem tissue to form bark. The continued production of new vascular tissue (xylem and phloem) forces the stem to expand outward. Older phloem and cork are eventually sloughed off, and continue to be replaced with more bark. The alternating phloem and cork tissues can often be distinguished by the layers of phloem fibers.
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Unformatted text preview: patterns in bark. The bark pattern of a tree is also a species characteristic. In contrast, all of the secondary xylem is retained as the stem expands, forming the wood portion of the stem. Tissues in Secondary Growth Xylem - wood Cells that mature inward from the vascular cambium are xylem tissue. This tissue forms the part of the stem we call wood. Wood forms the bulk of secondary growth, and, as we know, can have a great volume. Most eudicots have some secondary growth in vascular tissue. All woody plants (shrubs and trees) are perennials with significant secondary growth. All conifers are also woody plants. Some monocots are woody, but they have very special ways of obtaining strength and dimension and will be discussed at the end of this section....
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