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 noted that these lacunae were arranged in four rows around the central cylinder and usually separated by row of collenchyma cells (that rich by starch grain) between the lacunae adjacent.
Laminartype collenchyma was observed in sub-epidermic location, surrounding the whole perimeter of the petiole.
The main vascular strands strengthened by laminar collenchyma are concave but with a few small accessory strands in the concavity.
Early work by Ambronn (1879-1881) described some of the variation in collenchyma to be found in the family, and Keating (2000) and Goncalves et al.
These include types or states of ground tissue, vascular bundles, fibers, trichosclereids, collenchyma, and laticifers.
Collenchyma C = cap over phloem; B = banded; Bi = banded interrupted; Sb = strands between outer vascular bundles; Sv = strands opposite outer vascular bundles [on same radii] but not as bundle caps; - = absent.
A preliminary survey of petiolar collenchyma in the Araceae.
Pith, xylem, phloem cortex and epidermis are found in stem, in addition to angular collenchyma tissue in cortex cells.