Educational tissue: functions and structure

The evolution of flora and faunagradually led to the complication of their organization. Therefore, the modern variety of species is so great that it simply amazes imagination. The complication of the internal structure was reflected in each evolutionary branch.

This particularly affected plants thatmanaged to transform from the lower underwater species to the higher representatives settled around the globe, having a complex internal and external structure. A big role in this was played by the development of special structures - tissues, which constitute the main part of the individuals of this kingdom.

Meristem: definition and concept

In total, there are five main types of tissues of plant organisms. Among them are the following:

• meristems, or educational tissues;
• storing;
• conductive;
• mechanical;
• basic.

Each of them has a special structure, differenttypes of cells, and performs a certain important function in the life of the plant. Special attention deserves the educational fabric, because it gives rise to virtually all the rest and provides the main distinctive feature of plants from other living organisms - unlimited growth throughout life.

If we give a more precise biologicaldefinition of this type of tissue, it will sound like this: educational tissue, or meristem - is the general name for a special kind of tissue that consists of life-active cells, constantly dividing and providing growth and development of the plant as a whole.

In addition, it is meristems that give rise to manyother types of tissues in the body. For example, mechanical, conductive, cover and other. Due to them healing of injured sites on the body of the plant takes place, rapid restoration of lost structures (leaves, parts of the stem, root). One can say with certainty that educational tissue is one of the most important, which allows plants to exist. Therefore, its structure and functions are discussed in more detail.

Cells of the educational tissue. general information

There are two main types of cells that make meristems:

1. Polygonal, or isodiometric. They contain a very large nucleus, which occupies almost the entire internal space. They have ribosomes, mitochondria, small vacuoles scattered along the cytoplasm. The shell is rather thin. Between each other there are quite a few loose ones. Such cells form eumeremes. They give rise to all types of tissues, except conductive.
2. Proximal cells. On the contrary, they have very large vacuoles filled with cell sap. They are connected more densely with each other, the shape is elongated, cubical or prismatic. The educational fabric, built from them, gives rise to the conducting systems, cambium and prokambia of plants.

Thus, depending on the type of cells that form the tissue, the function it performs is also determined.

Also, two more types of meristem cells can be distinguished:

1. Initsialnye - actively dividing throughout the life of the cells, ensuring the accumulation of the total mass of the educational tissue. They also give rise to another group.
2. Derived cells - may differ from the previous form, size, number of vacuoles and other parameters.

These types of structures in some plant species may in general be indistinguishable, at least morphologically.

In general, the structure of the educational tissue allows us to distinguish several types that make up its classification.

Classification of meristems

Several different signs can be used as a basis. The first of these is the morphology of the cells that make up the tissue. According to this feature distinguish:

• lamellar meristems - cells of a cubic form with a single-layered shell, forming a cover cloth;
• columnar educational tissues - form the core of stems and trunks of trees, prismatic cells with a dense shell;
• massive meristems - give rise to growth in thickness, are represented by polygonal cells.

The next sign for classification is the ability to differentiate into other structures. On this basis, all meristems can be divided into six groups:

1. Embryonic educational tissue. Its name speaks for itself. Forms the primary tissues of the embryo.
2. Apical meristems, also called apical. Form: prokambia, epidermis, conducting tissues, parenchyma.
3. Wounded educational tissues. They are formed on the site of damage and provide a quick recovery of the lost organ or delaying the wound.
4. Intercalary - provide intercalary growth of plants in height and width.
5. Lateral, or lateral - provide a thickening of the axial structures of the body due to the deposition of cambium or phallogen.
6. Marginal meristem - it forms the leaf of the leaf.

The last classification, according to which it is possible to divide all meristems into two groups, is genetic. On it they are divided into:

• primary - related to the germinal and apical tissues;
• secondary - cambium, procambium and others.

Obviously, various signs of classification confirm the importance of the structures under consideration, especially their role in plant life.

Plate meristem

It is an educational fabric, the functions of whichare the formation of the epidermis of the plant. It is lamellar meristems that create cover tissues that protect the body from external influences, maintain a certain shape and structure.

The cells of the lamellar educational tissue are arranged in one row, very intensively divide, perpendicular to the working organ. As a result, the outer epidermis of the plant is formed.

Column tissue

Another name for these tissues is the core. They received it for the elongated prismatic shape of the constituent cells, which are closely aligned and have a thick enough shell.

Column tissue gives rise and completely forms the core of the stems and trunks of plants. The cells of this tissue are also divided perpendicularly with respect to the axial organs.

Massive meristems. a brief description of

Features of educational tissue thatis called massive, in that it enables the plant to accumulate a mass of undifferentiated cells, which lead to thickening and mass growth. This happens fairly evenly.

In the future, each part of the cell mass is transformed into this or that tissue, that is, it specializes and will perform its function. So, for example, sporangia and other tissues are formed.

Functions of the educational tissue of plants

The role played by meristems is enormous. It is possible to designate several basic most important functions that the tissues in question perform:

1. Provide the plant with unlimited growth throughout life.
2. They give rise to differentiation and specialization of all other types of tissues in the body.
3. Ensure the normal development of plants.
4. Eliminate damage and restore lost structures.

However, the main function to be executededucational tissue is the multiple division of cells and the accumulation of them in a large mass for the possibility of constant use by parts of the plant, and therefore, the preservation of its growth and activity throughout life. It is for this reason that there are no such tissues in the body of animals and humans. After all, they grow only to genetically determined (originally embedded in the genome) sizes.

Apical meristem

This educational fabric, the functions and structure of which we will consider, is one of the most important of all types of meristems. There are a number of reasons for this.

1. It is the apical tissue called also apical, since after the development of the embryo, it remains in the cone of growth (the tip of the shoot).
2. The apical meristem allows the stem and roots to grow in length.
3. Over time, it is the apical tissue that transforms into the floral and meristem of the inflorescence, allowing the flowers to form with all its parts.
4. It gives rise to all other types of educational tissues.

Therefore, we are talking about the high degree of significance of the apical meristems in plant life.

This variety of tissue has several derivatives, which it forms in the body of the plant. They are as follows:

• cover cloth;
• protoderm;
• procambium;
• conductive tissues;
• basic;
• massive.

Along with the apical go in value andlateral, or lateral meristems. They give rise Kambia fellogenu and form a so-called annual rings, which are clearly visible in cross sections of the stems and trunks.

Primary educational tissues

These include those that are first laid inthe body of the embryo. First of all, these are meristems of the embryo and apical (apical). Some of them last a lifetime, while others die, forming the primary body of the plant.

Since the apical meristems have already been considered in more detail above, there is no point in repeating it again. Primary tissues are the apical educational structures.

Secondary meristems

This group includes a massive meristem,It allows the plant to grow mass at later stages of development. It is an educational fabric, whose functions consist, mainly, in the formation of thickenings of the axial organs of plants.

A special role in this play cambium and phellogen. Most often secondary secondary meristems enter into action after the termination of the apical growth of the plant, but there are also exceptions. As, for example, in the case of cambium.

Also important is the importance of wound meristems, which lead to the formation of callus - the mass of cells. They tighten the place of injury or damage to the plant.