Plant tissue.

Proceedings describing animal and plant tissue, appeared in the XVII century.First-anatomists Botany - Grew and Malpighi - examined the most important of them, and introduced concepts such as prosenchyma and parenchyma.In general, the study of the structures involved in biology.Fabrics are differences in composition, tasks, the origin.Next, consider the more basic features of these structures.The article is provided with a table of plant tissues.In it you can see the main categories of structures, their location and the tasks.

Biology tissue.Classification Scheme

separation structures in accordance with the physiological tasks has been developed and Gaberlandtom Shvendenerom at the turn of XIX-XX centuries.Plant tissues are groups of elements having the same origin, a uniform composition and performing one task.Classification of structures is carried out according to different criteria.For example, plant tissues include:

• Main.
• conductive.
• meristem (educational).
• Cover.
• Secretory.
• Mechanical.

If plant tissues are composed of cells having more or less the same structure and the tasks they are called simple.If the items are not the same, then the whole system is called a complex or complicated.Types of plant tissue in a category are divided in turn into groups.For example, educational structures include:

• Apical.
• side - secondary (phellogen, cambium) and primary (pericycle, procambium).
• Wound.
• gusset.

types of the main type of plant tissue include store and assimilation parenchyma.Conductive structures considered phloem (bast) and xylem (wood).

Cover (border) plant tissues:

• Exterior: secondary (periderm), primary (epidermis), tertiary (ritidom or peel);VELAM, rizoderma.
• Internal: exogenous and endoderm, parietal cells of the vascular bundles of the leaves.

mechanical structure (skeletal, support) are divided into Sclerenchyma (sklereidy fibers) collenchyma.And the last group are the excretory (secretory) tissue of the plant organism.

educational structure: general information

These plant tissue (meristem) are a group of young constantly, actively dividing cells.They are located in areas of growth of various organs.For example, they may be located on the tops of the stems, the roots and tips of the other locations.Due to the presence in the tissue of the plant cell is a continuous growth of the culture and the formation of permanent members and organs.

Features meristem

Depending on the location of the educational fabric of the plant cell, it can be the apical (apical), side (lateral) gusset (intercalary) wound.Also, the structure is divided into secondary and primary.The latter include apical types of plant tissue.These structures is determined by the growth of culture in length.In higher lower organized plants (ferns, horsetails) apical meristem differ weakly expressed.They are represented by only a single initial, or primary cell.In angiosperms and gymnosperms apical meristem expressed quite well.They are represented by a number of initial cells, which form the growth cone.Lateral structures usually are secondary.Through them carried proliferation roots, stems (axial bodies in general) in thickness.Lateral types of plant tissue - it phellogen and cambium.Thanks to the work of the first is the formation of the roots and stems of cork.To this group belong fabric airing - lenticels.Lateral meristem as the cambium, the structural elements are formed phloem and wood.In periods of adverse life plants is slowing down or complete termination of the cambium.Intercalary meristem usually are primary.They are saved as separate sections in the areas of active growth: at the bottom of interstices and leaf stalks of cereal, for example.

Covering structure

functions of plant tissues of this group is to protect crops from adverse effects of environmental factors.Negative impact, in particular, should be considered excessive evaporation, solar overheating, drying wind, mechanical damage, ingress of bacteria and pathogenic fungi.There are primary and secondary coating fabric.The first category includes rhizodermis and the skin (epidermis).Secondary coating fabrics believe phelloderm, cork cambium, cork.Features

structures

Peel covered all organs from annual plants, perennial tree crops in the current growing season - green shoots, in general, plants - herbaceous aerial parts.The latter, in particular, are the leaves, flowers, stems.

structure of plant tissues: the epidermis

Its members tend to include a single layer of closed structural elements.In this intercellular space available.Epidermis fairly easily removed and a transparent thin film.It is a living tissue, which includes the gradual layer protoplast with a nucleus and leucoplasts, large vacuole.The latter covers almost the entire cage.The outer wall of the structural elements of a thickened epidermis and the inner and side - thin.The latter have pores.The main objective of the epidermis is the regulation of transpiration and gas exchange.It is carried out largely through the stomata.Inorganic compounds and water penetrate the pores.Different plant epidermal cells differ in size and shape.Many monocots have structural elements that extend in length.Most plants have a bipartite winding side walls.This increases the density of their connection with each other.Structure of the epidermis in the upper and lower part of the sheet is different.Fell more stomata than the top.In aquatic plants with leaves floating on the surface (water lily, egg capsules), has its own peculiarities.They stomata present only on top of the plate.But in plants, fully immersed in the water, forming data available.

stomata

This highly specialized formation in the epidermis.Stomata consist of 2 guard cells and slit - education among them.Structural elements have a crescent shape.They regulate the size of the slot-like formation.It, in turn, may be closed and opened in accordance with the turgor pressure in the locking element depending on the concentration of carbon dioxide in the atmosphere and other factors.During the day, the stomatal cells are involved in photosynthesis.During this period, turgor pressure is high, and the formation of a slit open.At night it is, on the contrary, is closed.This phenomenon is also observed in the dry season, and wilting leaves.It is due to the ability of stomata to store moisture inside.

basic structure

parenchyma occupies most of the space between the other permanent tissues in the stem, roots and other plant organs.Basic structure mainly composed of living cells having a variety of shapes.Cells can meet, thin-walled, but sometimes found and thickened, lignified, with simple pores postennoy cytoplasm.From the pulp parenchyma consists of leaves and fruits, roots and stems of the core, their bark.Several subgroups of this tissue.Thus, among the main structures distinguished: pneumatic, aquifer, store and assimilation.Functions of this category of plant tissue is to store nutrient.

chlorophyll parenchyma

Hlorenhima - assimilation tissue - a structure in which photosynthesis takes place.Its elements are distinguished by thin walls.They present nucleus and chloroplasts.The latter, as the cytoplasm, located postenno.Hlorenhima Located directly under the skin.Mostly it is concentrated in the young green shoots and leaves.

Aerenchyma

pneumatic fabric is a structure with sufficiently developed intercellular spaces in different organs.Most of all it is characteristic of wetland, water and coastal water cultures whose roots are in the oxygen-poor mud.The air reaches the lower bodies by means of transfer.In addition, communication between the intercellular spaces and the atmosphere is carried out by the original pnevmatod.Due Aerenchyma share of the plant is reduced.This is likely explained by the ability of water to maintain the vertical position of crops and leaves - were on the surface.

aquifers

This fabric keeps moisture in the stems and leaves of succulent plants and crops in saline areas.The former, for example, include cacti, Jade, agave, aloe and others.The second group - Grebenshchikov, sarsazan, hodgepodge, and others.Well developed this fabric from sphagnum moss.

to stock structure

In these tissues, at some point in the development of culture begins to lay metabolic products.In particular, fats, carbohydrates, and others.Cells in storage tissues, generally thin-walled.The structure is widely represented in the thickening of the roots, bulbs, tubers, stems core, seed germ, endosperm, and other areas.

Mechanical covers

supporting tissues act as a kind of reinforcement, or "stereoma" (from the Greek. "Solid", "robust").The main objective is to provide drag structures dynamic and static loads.Accordingly, the fabrics have a definite structure.In terrestrial crops they are more advanced in the axial section of the shoot - stem.The cells can be located on the periphery of, or separate regions of a solid cylinder.

collenchyma

It is a simple primary supporting tissue from a living cell contents: the cytoplasm, nucleus, sometimes chloroplasts.There are three categories collenchyma: loose, plate and angle.This classification is carried out in accordance with the nature of the thickening cells.If it's on the corners, the angled structure if parallel to the surface at the stem and fairly evenly, it collenchyma plate.Fabric formed from primary meristem and positioned under the epidermis at a distance of one or more layers of it.

Sclerenchyma

This manual is considered to be fairly common fabric.It consists of structural elements with lignified and thickened uniformly slotted walls and pores in a small amount.Cells in Sclerenchyma long drawn out, they are characterized prozenhimnaya shape with pointed ends.

conductive structures

These fabrics provide transportation nutrient.It is carried out in two directions.Transpiration (ascending) current and aqueous solutions of salts is of tracheids and vessels from the roots to the leaves on the stem.Assimilation (downward) movement comes from the top to the underground through special phloem sieve tubes.The conductive fabric may be compared in some way with the circulatory system of humans because it has a radial and an axial network.Nutrients penetrate into every cell of the body.

Secretory fibers

secretory tissues - special education, have the ability to allocate or to isolate a liquid droplet environment and products of metabolism.Recent referred secrets.If they come from a plant that are involved in the secretion of the outer fabric, and if left inside - respectively engage the internal structure.Formation of liquid products due to the activity of the membrane and Golgi complex.Secrets of this type are designed to protect the plants from destruction by animals, damage to pathogens or insects.Endocrine structure are presented in the form of resin ducts, idioblast, aromatic channels mlechnikov, receptacle for discharge, and other glands.

Table of plant tissues