Just as in animals, in the bodies of plants have different tissue.Of these, built bodies, which, in turn, form the system.Structural unit as a whole is the same - the cell.
However, plant and animal tissue and differ in structure, and the functions they perform.Therefore, we try to figure out what these structures in flora.A more detailed look at what the mechanical plant tissue.
Fabrics plant
Total 6 groups can be identified in tissues of the plant body.
- Educational includes wound, apical, lateral and intercalary types.It is intended to restore the structure of plants, various types of growth, is involved in the formation of other tissues, new cells are formed.Depending on the function becomes clear which will be localized areas with educational fabric: petioles, internodes, root tip, the upper part of the stem.
- main consists of different types of parenchyma (columnar, pneumatic, spongy, is stored, water-bearing) and photosynthesizing parts.The function corresponds to the name: the storage of water, accumulation of reserve nutrients, photosynthesis, gas exchange.Localization in the leaves, stems, fruit.
- Conductive tissue - xylem and phloem. main purpose - transportation of minerals and water to the leaves and stems and reverse nutrient delivery to the places of accumulation.Settle in vessels of wood, specialized cells of the bast.
- Cover fabric include in its membership three basic varieties: it is jam crust epidermis.Their role in the first place - Protective and transpiration and gas exchange.The location in the body of the plant: the surface of leaves, bark, roots.
- Secretory tissue carry production of juice, nectars, metabolic products, moisture.Located in specialized structures (nectaries, mlechnikah, hairs).
- Mechanical plant tissue , its structure and functions will be discussed below in more detail.
Mechanical tissues: general characteristics
complex and heterogeneous weather conditions, climatic catharsis, is not always soft swings of nature - from all that protects human habitation.And often such a haven for animals are just a plant.And who will save themselves?Due to this they are able to withstand heavy wind and earthquakes, volcanoes and hail, snow and tropical storms?It turns out, helps them stand included in the structure - mechanical tissue.
This structure is not always evenly distributed in one and the same plant.Also, it is not the same content and different representatives.But to some extent it is at all.Mechanical plant tissue has a special structure, classification and functions.
functional significance
One name this structure speaks about the role and importance it has for the plants - the mechanical strength, protection, support.Often equated with mechanical tissue valve.That is a kind of skeleton, the skeleton, which gives support and strength throughout the plant organism.
These functions are extremely important mechanical tissue.Their plant is able to tolerate the presence of the strongest weather bad weather, while maintaining the integrity of all parts.Often you can see how the trees are shaken by strong winds.However, it does not break, showing the wonders of plasticity and strength.This occurs because the working mechanical properties of tissues.You can also see the stability and shrubs, tall grasses, dwarf shrubs, small trees.All of them are kept in good condition, though Steadfast Tin Soldier.
Of course, this is explained by the structural features of cell structures and types of mechanical tissue.You can divide them into groups.
Classification
There are three main types of structures, each of which has its own particular structure of mechanical tissue.
- collenchyma.
- Sclerenchyma.
- Sklereidy (often seen as part of sclerenchyma).
Each of these tissues can be formed from both the primary and of the secondary meristem.All mechanical tissue cells have thick cell walls strong, which largely explains the ability to perform these functions.The contents of each cell can be either alive or dead.
collenchyma and its structure
evolution of this type of structure is from the main plant tissues.Therefore, most collenchyma contains pigment chlorophyll and capable of photosynthesis.This fabric is formed only in the young plants, paving the authorities of their right under the cover, sometimes a little deeper.
Prerequisite for collenchyma - turgor of cells, only in this case it is able to fulfill its function of reinforcement, support.Such a condition is possible since all of the cells of the tissue - living, growing and dividing.Shell very thick, but saved pores through which moisture and takes the fence and installation of certain turgor pressure.
also the mechanical structure of this type of tissue involves several types of junction cells.On this basis it decided to allocate three types collenchyma.
- lamellar .The cell walls are thickened sufficiently uniformly arranged close to each other, parallel to the stem.The elongated shape (an example of a plant that contains the type of fabric, - sunflower).
- angled collenchyma - shell thickened unevenly, in the corners and in the middle.Meshed with each other by these parts, forming a small space (buckwheat, pumpkin, sorrel).
- Loose - the name speaks for itself.The cell walls thicker, but their combination - with large intercellular spaces.Often performs photosynthetic function (belladonna, mother and stepmother).
again should be pointed out that collenchyma - a fabric only young, odnogodovalyh plants and their shoots.The main localization in the body of plants - stalks and major veins in the stem on each side in the shape of a cylinder.This manual contains the only living tissue, neodrevesnevshie cells without impeding the growth of plants and their bodies.
Functions
photosynthetic addition, can also be called as the main function of support.However, she does not play such a big role in this, as the sclerenchyma.Nevertheless collenchyma tensile strength comparable to the strength of metals (aluminum, for example, and lead).
Also features a mechanical tissue of this type are also due to the ability to form secondary woody shell of the old organs of plants.
Sclerenchyma, cell types
Unlike collenchyma, the cells of the tissue are often lignified shell, greatly thickened.Live content (protoplast) will eventually die off.Often sclerenchyma cell structures are impregnated with special substances - lignin, which increases their strength many times.Fracture strength at sclerenchyma comparable with parameters of construction steel.
main cell types that make up a tissue following:
- fiber;
- sklereidy;
- structures included in the conductive tissues, xylem and phloem - bast fibers and wood (libriform).
fibers are elongated and pointed upward prozenhimnye structures with strongly thickened and woody shells, then very little.Localized in the end locations of the growth processes of the plant: interstitial stem, the central part of the root stalks.
Bast and wood fiber are important as the accompanying conductive tissues surrounding them.
avilable mechanical tissue sclerenchyma consist in the fact that all cells of the dead, with well-formed wood shell.Together, they give a huge resistance to plants.Sclerenchyma is formed from the primary meristem, cambium and procambium.Localized in the trunks (stems), stalks, roots, stalks, receptacle, stalk and leaves.
role in the plant body
performs the function of mechanical tissue sclerenchyma evident - providing a holistic good frame of sufficient strength, flexibility and strength to withstand dynamic and static effects from the weight of the crown (the trees) and natural disasters (allplants).
function of photosynthesis to sclerenchyma cells is uncommon due to the withering away of the live content.
Sklereidy
These structural elements of mechanical tissue formed from the conventional thin-walled cells by gradual withering away of the protoplast sklerifikatsii (lignification) shells and their multiple thickening.Such cells develop in two ways:
- from the main meristem;
- of parenchyma.
Ensure strength and stiffness can be sklereid, denoting the place of their location in the plant.Of these consists nut shells, fruit stones.
The shape of these structures can be quite different.Thus, the release:
- short rounded rocky cells (brahisklereidy);
- branched;
- greatly elongated - fiber;
- osteosklereidy - shaped like a human tibia.
Often such structures are found even in the fruit pulp, which protects them from eating a variety of birds and animals.Sklereidy all types of make up especially mechanical tissue, helping them to perform support functions.
value for plants
role of such cells is not only reinforcing functions.Sklereidy also help plants:
- protect seeds from temperature changes;
- avoid Fetus bacteria and fungi, as well as animal bites;
- form in combination with other mechanical tissue full stable mechanical frame.
presence of mechanical tissue in different plants
distribution of these types of tissue differently in different species of flora.For example, the least sclerenchyma contain lower aquatic plants - seaweeds.After all, for them the function of supporting playing the water, her blood pressure.
also not too lignified and stocking lignin tropical plants, all representatives of wet habitats.But the inhabitants of the arid conditions of mechanical tissue acquire the maximum.This is reflected in their environmental artist - Sclerophyll.
collenchyma is more characteristic for the annual bipartite representatives.Sclerenchyma, by contrast, mostly formed in monocotyledonous perennial grasses, shrubs and trees.
