Mechanical support fabrics

Mechanical support fabrics . Adaptation of plants to the terrestrial environment that increases the hardness of the vegetative body, which no longer receives the sustaining impulse of water in the air, allows plants to retain their shape and reach considerable heights and solidity. They are made up of compact cells , generally do not have intercellular spaces and with strongly thickened cell walls.

Summary

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• 1 General
• 2 Function
• 3 Classification
  • 1 Collenchyma
    • 1.1 Features
    • 1.2 Types of collenchyma
  • 2 Sclerenchyma
    • 2.1 Features
    • 2.2 Fibers
    • 2.3 Sclereids
  • 4 Source

General

Within the supporting tissues of the plant we have the collenchyma and the sclerenchyma . They are located in the bark of stems and roots, petioles, fruits, seeds, etc., and can accompany conductive tissues. It is suggested that its origin is from the fundamental meristem from the procambium and from the cambial activity in the case of the fibers.

These tissues are made up of cells with very thickened cell walls and, at times, thickened with lignin (a polymer with a complex structure that provides a significant stiffening reinforcement to the cell walls of the cells to which it adheres).

Function

Provide structural support, as well as give consistency and firmness to the plant.

Classification

There are two types of bra fabrics:

Collenchyma

It is a mechanical tissue adapted to support growing organs and adult herbaceous organs with or without minor secondary growth. It is the first supporting tissue on stems, leaves and flower parts and the main support of the leaves and some green stems in most dicotyledons.

characteristics

It is a living tissue made up of more or less elongated living cells, with thick primary lignified cellulose membranes. It is a simple tissue that consists of a single type of cell. It is similar in its characteristics to parenchymal cells and when they are together, there is a gradation between parenchymal and colenchymal cells.

The colenquimatosas cells can present chloroplasts in variable number have diverse lengths, they can be prismatic or of great dimensions and they form fibers of up to 2 mm in length, fusiform. In these are fields of primary pits, both in the thin parts of the cell wall and in the thickened ones. The cellulose cell wall has unevenly arranged layers.

This fabric combines considerable tensile strength with flexibility and plasticity due to the wall structure

Collenchyma types

• Angular: presents the greatest thickenings at the angles where several cells meet. The degree of thickening of the angles varies with the thickening of the other parts of the wall and the cell cavity can acquire a circular shape, if the thickening is massive.
• Laminar: thickening occurs mainly in tangential cell walls.
• Lagunar: the thickening of the wall leaves intercellular spaces it can happen that the thickening of the wall exists near said intercellular spaces.
• Annular: thickening is uniform around the cell.

Sclerenchyma

It is also a mechanical fabric. It has a very important function in supporting the organs that have stopped lengthening. They protect the softest parts of the plants and are most vulnerable to stretching, weight, pressure and flexing. So although it is distributed throughout the body of plants, whether they are structures with primary or secondary growth, it is more abundant in stems and leaves than in roots.

characteristics

Sclerenchymal cells show great variation in terms of shape, structure, origin and development; there is a gradation between the different types of cells. They lack a living protoplast when they reach differentiation. It can come in the form of elongated fibers , or short cells called sclereids .

Fibers

The fibers are elongated cells with pointed ends, with a more or less thick secondary cell wall with many layers and with a variable degree of lignification. They are classified according to their topographic position on the ground. Extraxillary fibers are those that are found in the phloem (phloem fibers), in the cortex (cortical fibers), or surrounding vascular bundles (perivascular fibers) and the xillary fibers are found in the xylem.

Sclereids

They are widely distributed in the body of the plant, arranged in isolation or in groups. They have very thick and lignified secondary walls that can often present the canaliculi, which are simple branched pits that cross the wall. Their shapes can be isodiametric, starry, branched, etc.