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2.2: Ground tissues

  • Page ID
    47206
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    The main tissue types of the ground tissue system are parenchyma, collenchyma and sclerenchyma. Parenchyma have thin walls of cellulose, whereas collenchyma have cell walls with thickened areas of additional cellulose. Sclerenchyma cells have lignified cell walls. They can be further categorised into narrow long cells (fibers) and cells of various other shapes (sclereids).

    Parenchyma

    Parenchyma cells with blue green thin cellulose cell walls.
    Parenchyma cells with blue green thin cellulose cell walls.
    Figure 2.3. Parenchyma cells with blue green thin cellulose cell walls. (Sean Bellairs CC: attribute, share alike).

    When parenchyma cells are modified to create tissues with air spaces for buoyancy or aeration of tissues, then the tissue is described as aerenchyma rather than parenchyma.

    Aerenchyma in the stem of the aquatic monocot Potamogeton
    Figure 2.4. Aerenchyma in the stem of the aquatic monocot Potamogeton. Large air spaces can be seen between the cells of the cortex. There is a single layer of epidermal cells and behind that a single layer of cortical parenchyma cells, then aerenchyma tissue for buoyancy and movement of oxygen to the submerged tissues (Berkshire Community College Bioscience Image Library, public domain).

    Collenchyma

    Collenchyma cells
    Figure 2.5. Collenchyma cells of Fraxinus (left). Upper cells are parenchyma, collenchyma with large dark cell walls and squat rectangular dermal cells at lower surface. (Jen Dixon (CC BY-NC-SA 2.0)). Collenchyma cells in celery (right) that are unstained and have large white cell walls (Sean Bellairs CC: attribute, share alike).

    Sclerenchyma

    Sclerenchyma cells have lignified cell walls. They can be of two broad types: sclereids and fiber cells.

    2.2.3.1 Sclereids

    Sclerenchyma cells
    Figure 2.6. Sclerenchyma cells with thick cells walls that are stained red due to lignin in the cell walls. (Sean Bellairs CC: attribute, share alike)
    Figure 2.6. Sclereid cells or stone cells in the pear fruit. The sclereid cells have thick red stained cell walls are surrounded by blue green stained parenchyma cells. (Berkshire Community College Bioscience Image Library, public domain).
    Figure 2.6. Sclereid cells or stone cells in the pear fruit. The sclereid cells have thick red stained cell walls are surrounded by blue green stained parenchyma cells. (Berkshire Community College Bioscience Image Library, public domain).

    2.2.3.2 Fibers

    Fiber cells are sclerenchyma cells that are long and thin.

    Drawings of stone cells
    Figure 2.7. Drawings of stone cells from the coconut shell and fiber cells from the bark of Sambucus nigra. (Source: Winton, A.L., Moeller, J., Winton, K.G.B (1916) The microscopy of vegetable foods, with special reference to the detection of adulteration and the diagnosis of mixtures. New York, John Wiley & Sons: not copyright).

     


    This page titled 2.2: Ground tissues is shared under a CC BY-SA license and was authored, remixed, and/or curated by Sean Bellairs (Charles Darwin University) .

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