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 ?
It was found that Selected - PSU cultivar was susceptible to aphids, having thin epidermis cell wall and collenchyma and had small-sized and a few number of epidermis which was unable to resist the destruction of aphids (Figure 1AB).
One excellent place to observe collenchyma is in the petioles of celery or beets.
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.
Such strands are most frequently encountered when there is little or no collenchyma development.
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).
Pith, xylem, phloem cortex and epidermis are found in stem, in addition to angular collenchyma tissue in cortex cells.
Leaf lamina presents in epidermis central vein, collenchyma in small amounts on both sides, parenchyma, secretory ducts and a single collateral vascular bundle, also in the U form (Figure 6C).
The epidermis is uniseriate and the cortex presents parenchyma and collenchyma (Figure 3B).