Collenchyma


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Collenchyma

A primary, or early differentiated, supporting tissue of young shoot parts appearing while these parts are still elongating. It is located near the surface, usually just under the epidermis. When observed in transverse sections, it is characterized structurally by cell walls that are intermittently thickened, generally in the corners or places of juncture of three or more cells. Collenchyma is typically formed in the petioles and vein ribs of leaves, the elongating zone of young stems, and the pedicels of flowers. See Cell walls (plant)

As in parenchyma, the cells in collenchyma are living and may contain chloroplasts and starch grains. The cell wall of a collenchyma cell is its most striking feature structurally and functionally. It is composed of cellulose and pectic compounds plus a very high proportion of water. The cytoplasm is very rich in ribosomes and ribonucleic acids in the early stages of development. Another striking feature of collenchyma cell walls is their plasticity. They are capable of great elongation during the period of growth in length of the plant. The plasticity of collenchyma is associated with a tensile strength comparable to that shown by fibers of sclerenchyma. The combination of strength and plasticity makes the collenchyma effective as a strengthening tissue in developing stems and leaves having no other supporting tissue at that time. See Epidermis (plant), Parenchyma

Collenchyma

 

one of the primary mechanical tissues of plants. The cells are parenchymal or elongated, with variously thickened membranes. There are angular, lamellar, and lacunar collenchymata; these variations are determined by the distribution of the thickenings in the angles of the cells (along tangential walls or near intercellular spaces). Collenchyma is found mainly in the primary cortex of young growing stems of dicotyledonous plants. Collenchyma cells are living; in a state of turgor they are stable. The cell walls consist primarily of either cellulose or cellulose and pectin. In the thicker stems of herbaceous plants, collenchyma often performs a storage or assimilative function.

collenchyma

[kə′leŋ·kə·mə]
(botany)
A primary, or early-differentiated, subepidermal supporting tissue in leaf petioles and vein ribs formed before vascular differentiation.
References in periodicals archive ?
4 = visual damage on leaves and flower buds 76 - 100 % Moreover, collected samples were sectioned to study epidermis, collenchyma and chlorenchyma by Poornima et al.
Collenchyma cells usually occur as discrete groups of cells that form a tissue directly beneath the epidermis in stems and petioles, and they often border the veins in dicot leaves.
Laminartype collenchyma was observed in sub-epidermic location, surrounding the whole perimeter of the petiole.
Plant cells may be meristematic, parenchyma, collenchyma, or sclerenchyma in type.
In the adaxial surface, a cortical parenchyma is located below of epidermis, but in the abaxial surface, the cortical parenchyma is separated from the epidermis by a few layers of annular collenchyma (Figure 2G).
Nymphaea oxypetala stands out from the other evaluated species for having a greater number of differential characters, including angular collenchyma and the absence of bicollateral bundles in the petiole.
Collenchyma Plant cells that are closely compacted and provide structural support to the plant.
Axial parenchyma and vascular cambium showed medium activity of phenoloxidasc, this activity increased toward the periphery, principally in the suberized and collenchyma cells.
preserved epidermis reveals extensions of collenchyma and parenchyma that form triangular ridges, similar to those in winged stems of some
The individual tissues comprising the stem cross section (epidermis, collenchyma, chlorenchyma, phloem, cambium, xylem, and parenchyma) were examined to estimate the degree of cell wall thickening with advancing maturity across sampling dates.
A cross-section of the cotyledon petiole shows a hairy uniseriate epidermis, collenchyma, parenchyma and the double trace.
The cortex, in the first internodes, presented 2-3 layers of angular collenchyma, 5-6 layers of parenchyma cells (Figure 2e), and the starch sheath (data not shown).