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| Anatomy of a Typical Monocot Stem |
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| Example: Zea mays (Maize) |
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| A transverse section passing through the stem of Maize reveals the following details. |
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| Epidermis |
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| Epidermis is the outermost covering of the stem represented by a single layer of compactly arranged, barrel-shaped parenchyma cells. Intercellular spaces are absent. Trichomes are absent. A cuticle is present. The epidermis contains numerous minute openings called stomata. |
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| Hypodermis |
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| Hypodermis is a region that lies immediately below the epidermis. It is represented by a few layers of compactly arranged sclerenchyma cells. |
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| Ground Tissue |
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| Ground tissue is a major component of the stem. It is undifferentiated. The ground tissue is represented by several layers of loosely arranged parenchyma cells enclosing prominent intercellular spaces. The ground tissue is meant for storage of food. |
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| Vascular Bundles |
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| They are found irregularly scattered in the ground tissue. Towards the periphery, the bundles are smaller in size while towards the centre, they are larger in size. The smaller bundles are younger, while the larger ones are older. Hence, the arrangement is described as centrifugal. Each vascular bundle has a covering called bundle sheath formed by a single layer of sclerenchyma cells. The vascular bundle encloses both xylem and phloem. Xylem is found towards the inner surface and phloem towards the outer surface. Cambium is absent. Hence the vascular bundles are described as conjoint, collateral and closed. In the xylem, there are two metaxylem and two protoxylem vessels arranged in 'the shape of 'Y'. The lower protoxylem vessel is non functional and remains as a water filled cavity called lisigenous cavity or protoxylem cavity. Xylem is described as endarch. In the phloem, only sieve tubes, companion cells and phloem fibres are present. Phloem parenchyma is absent. |
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| T.S. of a Monocot Stem (Maize) |
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| Cross-Section of a Monocot Stem |
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