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| Collenchyma |
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| It is a type of simple permanent tissue, which is mainly meant for providing mechanical support to the shoot system of a plant. Collenchyma is completely absent in the root. |
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| It is composed of elongated cells that are compactly arranged. Sometimes, the cells may enclose small intercellular spaces. In a section, the collenchyma cells appear either polygonal or spherical or oval. The cells are characterised by the presence of a cell wall, which is unevenly thick. The cell wall is composed of a primary wall made up of cellulose and at certain places, it is deposited with a secondary wall made up of hemicellulose or pectin. Every cell has a large, prominent vacuole filled with certain secretory products. Surrounding the vacuole, a granular cytoplasm is present. A nucleus is usually found situated just above the vacuole. The cell organelles are usually found in a functional state. Collenchyma is commonly described as a simple, living, mechanical tissue. |
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| Collenchyma Cells |
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| Based on the nature of secondary thickenings in the cell wall, collenchyma can be distinguished into three types. |
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| In this type the deposition of hemicellulose and pectin occurs only in the angles between the cells. The cells are compactly arranged and intercellular spaces are absent. It is found in the stem, usually below the epidermis, forming a region called hypodermis. |
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| In this type, the deposition of hemicellulose and pectin occurs only at the crosswalls separating the adjacent cells. The cells are compactly arranged without any intercellular spaces. This type is found usually in the petiole of leaves. |
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| in which the cells are either spherical or oval in shape and enclose small intercellular spaces. The deposition of hemicellulose and pectin occurs only along the border of intercellular spaces. This type of collenchyma is usually found in the fruit wall. |
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| Types of Collenchyma |
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| Functions of Collenchyma |
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| Collenchyma is involved in the following functions in the plant body. |
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| Providing mechanical support |
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 Exchange of respiratory gases |
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 Photosynthesis |
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 Storage of secretory products |
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