Plants, as well as all living organisms on Earth, consist of cages which congestions form fabrics. The last are very diverse and differ depending on the carried-out functions.
Any fabric represents group of the cages similar in structure and to origin and also performing the general function. All fabrics are divided into 2 big groups:
- simple – consisting of one type of cages;
- difficult – consisting of different types of cages which, except the main, perform also additional functions.
Morphological features of fabrics (i.e., features of the building) depend on the functions which are carried out by them. At plants allocate the following types of fabrics:
- educational,
- integumentary,
- mechanical,
- carrying out,
- the main.
Let's consider short characteristic of everyone them them.
Educational
Educational fabrics are also called meristems that in translation from Greek "meristos" means "divisible". It is simple to guess that their main function is ensuring growth of a plant due to almost constant division of the cages entering fabric.
Cages – rather small as just do not manage to grow. It is possible to distinguish thin covers, a dense adherence of cages from the main features of their building to each other, large kernels, abundance of mitochondrions, a vacuole and ribosomes. Mitochondrions serve as suppliers of energy for various cellular processes, and ribosomes synthesize the protein molecules necessary for formation of new cages.
Allocate 2 subtypes of meristems:
- Primary – providing primary growth in length. It makes a seed germ, and at an adult plant this fabric remains in tops of escapes and tips of roots.
- Secondary – providing growth of a stalk in the diameter. This group is divided into top, side, inserted and wound secondary meristems. They consist of a cambium and phellogen.
Integumentary
Integumentary fabrics form the surface of a body of plants, are on all bodies. Their main function is ensuring resistance of an organism to mechanical influences and sharp temperature fluctuations and also protection against excessive evaporation of moisture and penetration in pathogenic microorganisms.
These fabrics are divided into 3 main types:
- Epidermis (also call epidermis or a thin skin) – primary fabric from one layer of small transparent cages which densely adjoin to each other. It covers leaves and young escapes. The surface of this fabric has the vocational educations called ustyitsa who regulate processes of gas exchange and the movement of water on a plant body. Also it is usually covered with a special cuticle or a wax raid that represents additional protection.
- Periderma – the secondary fabric covering stalks and roots. It succeeds epidermis at perennial plants, is more rare – at one-year. Consists of a pith cambium (differently called phellogen) – a dead layer of cages which walls are impregnated with waterproof substance. It is formed by division and differentiation of phellogen inside and outside therefore 2 layers – a felloderma and a fellema respectively are formed. Thus, the periderma has 3 layers: fellema (stopper), phellogen, felloderma. As cages of a stopper are impregnated suberiny – zhiropodobny substance which does not pass air and water thereof contents of cages die off and they are filled with air. The dense pith layer is reliable protection of plants against adverse external factors.
- The crust is the tertiary fabric succeeding a stopper. As a rule, it makes bark of trees and some bushes. It is formed as a result in deep fabrics of bark new sites of phellogen of which, respectively, new layers of a stopper are formed are put. Because of it external fabrics are isolated from the central part of a stalk, deformed and die off, and the surface of a stalk becomes covered with dead fabric from several layers of a stopper and the died-off sites of bark. Certainly, the thick crust provides higher protection, than a stopper.
Mechanical
These fabrics consist of cages with thick covers. They provide peculiar "framework", i.e., keep plant shape, do it to more resistant to mechanical influences. It is possible to distinguish a powerful thickening and an odrevesneniye of covers, a close adjunction of cages from features of these fabrics to each other and absence in their walls of perforation. Most strongly they are developed in stalks where are presented by woody and bast fibers, but also is in the central part of roots. Allocate 2 types of mechanical fabric:
- The collenchyme – consists of living cells with unevenly reinforced covers that allows to strengthen the young growing bodies considerably. Besides, cells of this fabric very easily stretch therefore do not prevent lengthening of a plant.
- Sklerenkhim – consists of the extended cages with evenly reinforced covers which, besides, often are lignified, their contents die off at early stages. Covers of these cages have very high durability therefore they form fabrics of vegetative bodies of land plants, making their axial support.
Carrying out
The carrying-out fabrics provide transfer and distribution on a body of a plant of water and mineral substances. Allocate 2 main kinds of such fabrics:
- Xylem (wood) – the main water carrying out fabric. Consists of special vessels – tracheas and tracheitises. The first represent hollow tubes with through openings. The second – the narrow, extended in length dead cages with the pointed ends and lignified covers. The xylem is responsible for transportation of liquid with the mineral substances dissolved in it by the ascending current – from roots to a land part of a plant. Also performs basic function.
- Floema (bass) – is presented by cribriform tubes, provides the return, descending current: carries the nutrients synthesized in leaves to other parts of a plant, including – to roots. Is in close interrelation with a xylem, forming together with it certain complex groups in bodies of plants – the so-called carrying-out bunches.
The main
The main fabrics (parenchyma), as follows from the name, form the basis of bodies of plants. They are formed by living thin-walled cells and perform several functions therefore they are divided into several versions. In particular, it:
- Assimilatory – contain a large number of chlorolayers, respectively, are responsible for processes of photosynthesis and formation of organic matter. Generally leaves of plants are created from these fabrics, slightly less them contains in young green stalks.
- Reserving – accumulate useful substances, including proteins and carbohydrates. These are fabrics of root crops, fruits, seeds, bulbs, tubers and stalks of wood plants.
- Water-bearing – accumulate and keep water. As a rule, these fabrics form bodies of the plants growing in an arid and hot climate. Can contain as in leaves (for example, at an aloe), and in stalks (at cacti).
- Pneumatic – due to a large number of the mezhkletnik filled with air transport it to those parts of an organism which message with the atmosphere is complicated. They are characteristic of water and marsh plants.
As we see, vegetable fabrics are not less diverse and complex, than animals. They reached the greatest specialization at angiospermous plants: at them allocate up to 80 types of fabrics.