plants.g. Animals.A.2 Avtrophic Organisms are: A. Viruses. Fish.V. Animals.g. Plants containing chlorophyll.a.3 Bacterial cell: A. NEON.B. Axon. Dendrit.g. Cholera Vibrion.A.4. A distinctive feature Vegetable cells are: A. nodes.b. Cytoplasm. Membranes.g. Cellulose cell wall.A.5 As a result of mitosis occurs: A. Isolation. Regeneration of tissues and organs of the body .. Digestion.g. Breathing.a.6 Indicate one of the positions of the cell theory: A. One drop of pure nicotine (0.05 g) is enough to kill a person. All new cells are formed in the division of the source cells. Viruses and bacteriophages - representatives of the kingdom of animals. Viruses and bacteriophages - representatives of the complexion of multicellular .A.7 reproduction is: A. Obtaining nutrients from the environment. Selection of unnecessary substances. In Play yourself like. Admission to the organism of oxygen.a.8 The process of the formation of female genital gamets is called: A. Ovogenesis. Spermatogenesis. Drombenieg. Division.9 Internal fertilization occurs: A. Akul.B. Schuk.V. Tesyan.g. Frogs. And 10 For the developing embryo person, the man is destructive: A. Walking outdoors. Compliance with the future mom's power mode. Narcotic dependence of a woman. Compliance with the future mother of the regime of labor and recreation. And.11 Indirect type of development - y: A. Human reasonable. Man apes. Clothy monkeys.g. Butterflies of cabbagers.A.12 Genopit is a totality of all: A. Signs of the body. Genov organisms.I. Bad habits. Useful habits. And at the dihybrid crossing is studied inheritance: A. Many signs. Three signs. Two signs. One feature. The situation of V. tasks with a brief replying point.1 Find compliance..1.Dominant feature in humans. A. Gray Eyes.2. Recessive sign in humans. B. Karie Eyes.I. Light hair.g. Black hair.1 2V. 2 Compare the characteristics of the cullless and sexual reproduction. Enter the response number to the desired column. Power reproduction. Dust reproduction1. In the process of reproduction, one individual is involved in 2. In the process of reproduction, two individuals of different floors are involved.3. The beginning of a new organism gives the zygote, resulting from the merger of the male and female genital cells.4. The beginning of a new organism (organisms) gives a somatic cell.5. Dysenteric chopstick.6. Male and female Ponded frogs.V.3 Select the correct answer. Write the numbers of the right statements. № ___________ 1. Dermatozoid - female sexual gates.2. Sperm - men's sexual gates3. Egg - men's sexual gamuta4. Egg - female sexual gamuta5.Onegenesis is the process of the development of egg cell .6. Ovogenesis - the process of developing sperm. 7. Spermatogenesis - the process of the development of egg cells.8. Spermatogenesis is the process of developing sperm9. Fertilization is the process of fusion of genital games: two spermatozoa.10. Fertilization is the process of fusion of genital games: two eggs.11. Fertilization is the process of fusion of genital hamet: spermatozoa and eggs. B.4 Set the right sequence of complication of organisms according to plan: non-pulmonary forms Life-prokaryoti-eukaryota. Amone freshwater. Cholera Vibrion.V.5 heterozygous (AA) Black rabbit is crossped with a heterozygous (AA) black rabbit. 1. What splitting on the phenotype should be expected with such a crossing? A. 3: 1; B. 1: 1; V. 1: 2: 12. How many percent is the probability of the birth of white rabbits - (homozygous for two recessive genes - AA)? Answer: _________________ V.6 Carefully read the text, think and answer the question: "Recall the possible evolutionary role of symbiosis of scientists forced the study of the internal structure of the cell - in the middle of the last century after the appearance of an electronic discovery microscope in this area, one after the other appeared. It turned out in particular that not only chloroplasts of plants, but also mitochondria - "energy plants" of any real cells - in fact similar to bacteria with not only externally: they have their own DNA and they multiply independently of the cell - the owner. "(based on the magazine materials" Around the world"). What organides have their own DNA?

"Root systems The set of all the roots of one plant forms the root system. The root system includes morphologically different roots: the main, side and ... "

Root morphology. Eugene morphology. Metamorphosis

Root - axial body, has radial symmetry and

unlimited long can grow long. The main function of the root -

absorption of water and minerals. Besides this, roots can

perform other functions:

Strengthening plants in the soil;

Synthesis of various substances and their transport to other organs of the plant;

Power supply of nutrients;

Interaction with roots of other plants, microorganisms, mushrooms living in the soil.

Root systems The set of all the roots of one plant forms the root system. The root system includes morphologically different roots: main, side and apparent.

The main root develops from the embryonic root. Side roots arise at the root (main, lateral, appling). Pressure roots are very diverse. They arise on the leaves and stems.

1 - Main root, 2 - Putitive roots, 3 - side roots Types of root systems in higher disputes (plaues, horsages, ferns) There is no seed, and therefore the main root. Their root system is formed by the apparent roots and is called primary homoris (Greek. Homoos - the same; riza - root).

The appearance of seeds with the embryo and the main root of seed plants gave certain advantages. Such an root system consisting of the main and apparent with side roots is called alloriz (Greek.

alos - another).

In many coated bridge, the main root of the seedling quickly dies and the root system (secondary homorisal) consists of pressing roots.

According to other morphological features, the rod (the main root is strongly developed and is well noticeable) and the urine (the main root is immeasured or there is no) root systems.

Another morphological classification takes into account the mass distribution of the roots by the horizons of the soil. Select surface, deep and universal root systems.

1 - primary homorisal, 2-4 - alloriznaya, 5 - secondary homooris; 2-3 - Rod, 5

- urine; 2 - deep, 1.3 - surface, 5 - Universal modifications of roots roots of roots are formed from the main root, in which spare nutrients are deposited.

Characteristic for beets, radish, carrots.

Root tubers (cones) - Spare nutrients are deposited in lateral and apparent roots.

There are at the batte, dahlia.

Mikoriza (Mribocornia) - roots' tips with living with them in symbiosis gifs mushroom.

The mushroom feeds on organic substances from plant tissues, and it delivers mineral substances from the soil.

Nodules - formed by nitrogen-fixing bacteria that are on the roots.

Retracting roots - can shorten from their foundation. Their shortening leads to an accumulation of escape into the soil.

Air roots - there are many tropical epiphytic plants. These roots are able to absorb moisture from atmospheric air.

The respiratory roots are well developed in some tropical trees living on the swampy coasts of the oceans. At the ends of these roots there are holes where air enters.

Wild roots - formed in trees living in mangrove thickets. Due to the strongly branched roots, the trees distribute their mass on them ("Skiing Effect").

We depart from the base of the table arcuate and perform a reference function.

Root backups are laid on the branches and dried down.

Having achieved soil, grow strongly, allowing the tree to occupy a huge area.

Serve to maintain the crown.

Meet Banyan.

Root trains are found in Ivy. Develop on shoots.

With the help of such roots, escape can grow up vertical support.

- & nbsp- & nbsp-

Types of kidneys:

A - vegetative kidney; B - generative kidney; B - vegetative-generative kidney; 1 - Required stem; 2 - renal scales; 3 - Engagement flowers; 4 - Apparel leaves.

Branching of shoots Branching - education of branched steps. Due to the branch, an increase in the surface of the plant occurs. The main methods of branching: dichotomous, monopodial and sympodial.

Dichotomic branching is the most ancient type of branch.

It is found in algae, plauines, etc.

Monopodial branching - the top kidney forms the main axis. The main trunk is stronger. It is straight and evenly thickened.

Sympodial branching - escape consists of a number of axes of different orders. The next season, the elongation of escape occurs due to the nearest side kidney. It occurs at the overwhelming majority of coated.

A variant of sympodial branching is falsely acid: the top kidney dies, and the two opposite side kidneys form two upper escapes (horse chestnut, lilac).

Branch of shoots:

1 - the top dichotomous; 2 - side monopodial; 3 - side sympodial; 4 - side sympodial (false).

A special form of branching of shoots is a bunch. The base of the main escape is formed a group of lateral shoots. Branching comes from shortened escape units located under the soil or at the soil level.

Education of wheat:

1 - grain; 2 - apparent roots; 3 - side shoots.

By the nature of the location in space, shoots are:

strengthening, with growing vertically upstands, raising - shoots, first growing in a horizontal, and then vertical direction, sharpening - growing more or less horizontally. The creeping shoots are like sharpening, but unlike them are rooted with the help of the apparer roots formed in the nodes (strawberries). Curly shoots are able to charge around other plants or any supports (field field, hop), climbing shoots have devices (mustlemen, suckers, hooks, etc.) for hold on supports or on other plants (peas, grapes, ivy) .

Types of shoots:

1 - reprehensible; 2 - lifting; 3 - creeping; 4 - swallowing; 5 - curly;

6 - climbing.

Weight modifications The overhead shadow modifications are shoots with long thin interstitial and scratch-like colorless, less often green leaves (sludge creeping).

Briefly, serve for vegetative reproduction and settlement. Strawberry teams are called mustache.

Spines of shooting origin overlook the sinuses of the leaves and perform mainly protective function. They may be challenged (hawthorn) and branching (Glootichia).

The mustache is also formed from the kidneys and develop in plants with a subtle and weak stem, unable to independently maintain a vertical position (watermelon, grapes).

Buladian - side shoots with green flat long stems capable of unlimited growth and photosynthesis (asparagus), the leaves are reduced to scales.

Fillocladium - side shoots with green flat short stems (similar to the leaves), having a limited growth (igner).

They formed scratched leaves and inflorescences.

Strong succulents are the fleshy shoots of cacti, Mokhai. Perform water-saving and assimilative functions. Stems column-like, spherical or flat (have a kind of pellek). Arise in connection with reduction or metamorphosis of leaves.

Stem tubers - thickened stem with nutrient reserves (Kohlrabi).

Underground modifications of rhizome - a long-term underground escape (Lily of the Lily of the Lily of the Creek), performs the functions of renewal, vegetative reproduction and accumulation of nutrient reserves.

Externally resembles the root, but has the top and stubborn kidneys, the reduced leaves in the form of colorless scales.

The tuber is a modified escape, performs a sparkling function, often serves for vegetative reproduction.

The tuber is the thickening of underground escape (potatoes).

Bulb. It is a shortened, mainly underground escape (onions, garlic, lilies).

The stalking part of the bulbs (DC) with strongly shortened interstices carries numerous juicy modified leaves - scales.

Exterior dry scales perform a protective function. In juicy scales, spare nutrients are postponed.

Corm. It is a shortened escape, externally similar to the bulb (gladiolus). It is an intermediate form between tuber and bulbs. The main mass of the clubnelukovitsa is a thickened stem, covered

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Root system Root system

the totality of the roots of one plant, the total shape and character of the cut is determined by the ratio of the growth of the main, lateral and apparent roots. With the predominant GL growth. The root is formed by the rod k. s. (Lupine, cotton, etc.), with a weak height or dying ch. The root and the development of a large number of apparent roots - urine by K. s. (Buttercup, plantain, all monocoons). Degree of development K. s. Depends on the habitat: in the forest area on podzolic, poorly aerated soils K. s. 90% focused in the surface layer (10-15 cm), in the semi-desert zone and the deserts in some plants, it is superficial, using early rainfall (ephemers) or condensation. moisture, settling at night (cacti), others - reaches groundwater (18-20 m, spindle camel), third - universal, using different time moisture different horizons (Juzgun, Saksaul, etc.).

.(Source: "Biological Encyclopedic Dictionary." Ch. Red. M. S. Gilyarov; Radric.: A. A. Babaev, G. M. Vinberg, G. A. Zavarzin, and others - 2nd ed., Focused . - M.: Sov. Encyclopedia, 1986.)

root system

The combination of all underground root roots formed in the process of their growth and branching. The root system of the rod, where the main root prevails (eg, at the species of ses. Legumes), the urine, formed from numerous, similar to the size of the roots (in cereals), and the branched, in which are allocated somewhat identical to the degree of root development (many trees). The total area of \u200b\u200bthe surface of the root system can be very significant. It is estimated that the rye plant has OK. 14 million roots, total area The surface of which is 232 m².

.(Source: "Biology. Modern illustrated encyclopedia." Ch. Ed. A. P. Gorkin; M.: Rosman, 2006.)

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Lecture number 5. root and root system.

Questions:

Zones growing root.

Apical meristem root.

Primary root structure.

The secondary structure of the root.

Determining the root and its functions. Classification of root systems by origin and structure.

The root (lat. Radix) is an axial organ with radial symmetry and an increase in length as long as the apical meristem is preserved. From the stem root morphologically different in that the leaves never occur on it, and the apical meristem, as a thimble, is covered with a root case. The branching and the imposition of applying kidneys in cornerootry plants occurs endogeneously (intrafno) as a result of pericycle activities (primary lateral meristem).

Root functions.

1. The root absorbs water from the soil with mineral substances dissolved in it;

2. Perform an anchor role, fixing the plant in the soil;

3. serves as container nutrients;

4. Takes part in the primary synthesis of some organic substances;

5. In the rooted plant plants performs the function of vegetative reproduction.

Classification of roots:

I. By origin Roots divide on main, podid and side.

Main root It develops from the germs of the seed root.

Putting rootsor adventitive roots (from the lat adventicius - the succulent) are formed on other plants (stem, sheet, flower) . The role of the apparent roots in the life of herbaceous coated brimmed is enormous, since adult plants (both monocyan and many dicotyathic) root system mainly (or only) consists of prescript roots. The presence of apparent roots in the basal part of the shoots makes it possible to easily multiply the plants artificially - dividing them into separate shoots or groups of shoots with apparent roots.

Sideroots are formed on the main and pressing roots. As a result of their further branching, side roots of higher orders appear. Most often branching occurs until fourth-fifth orders.

The main root has positive geotropism; Under the influence of earthly attraction, it deepens to the soil vertically down; For large side roots, transverse geotropism is characterized, i.e., under the action of the same strength, they grow almost horizontally or at an angle to the surface of the soil; Thin (suction) roots geotropy do not possess and grow in all directions. The growth of the roots in length is periodically - usually in spring and autumn, in thickness - starts in the spring and ends in the fall.

The elimination of the tops of the main, lateral or apparent root sometimes causes the development of a side, growing in the same direction (in the form of its continuation).

III. In form The roots are also very diverse. The shape of a separate root is called cylindricalif for almost the entire length it has the same diameter. At the same time, it may be thick (peony, poppy); ishhurovidor strification (onions, tulip), and nitevoid(wheat). In addition, allocate journalroots - with uneven thickening in the form of nodes (Tollga) and clean-shaped -c is evenly alternating thickens and thin sites (cabbage hunger). Flashing rootsmay be conical, replicious, spheroid, spindle-shapedand etc.

Root system.

The combination of all the roots of one plant is called the root system.

Classification of root systems by origin:

the main root systemit develops from the germinal root and is represented by the main root (first order) with the lateral roots of the second and subsequent orders. Only the system of the main root develops in many trees and shrubs and in annual and some perennial herbatous dicotyledgles;

the system of the apparent rootsdevelops on stems, leaves, sometimes on flowers. The adventtive origin of the roots is considered as more primitive, as it is characteristic of the highest dispute, which have only the system of the apparent roots. The system of pressing roots in the coated bridge is formed, apparently, the orchid, from the seed of which develops the protocols (germs of the tuber), and subsequent roots are subsequently;

mixed root systemwidespread both among dicotyledan and monocoons. At the plant that has grown out of the seed, the main root system is first developing, but its growth continues for long - often ceases by the fall of the first growing season. By this time, the system of pressing roots on hypocotyle, epicotyl and subsequent meta-rooms of the main escape is consistently developing, and subsequently on the basal part of the side shoots. Depending on the type of plants, they are laid and developed in certain parts of meta chambers (in nodes, under and over the nodes, on interstitial) or throughout their length.

At the plants with a mixed root system, the main root system is usually insignificant part of the entire root system. Subsequently (on the second and in subsequent years), the apparent roots arise in the basal part of the second, third and subsequent shoots, and the main root system dies after two or three years, and the plant remains only the system of the apparent roots. Thus, during life, the type of root system changes: the main root system is a mixed root system - a system of pressing roots.

Classification of root systems in form.

Rod root system -this is a root system, which is well developed the main root, noticeably higher than the length and thickness of the side.

Urochka root system It is called with a similar magnitude of the main and lateral roots. It is usually represented by thin roots, although in some species they are relatively thick.

The mixed root system can also be a rod if the main root is much larger than the rest, urineif all the roots are most relatively equal. The same terms apply to the system of pressing roots. Within one root system, the roots often perform different functions. The roots of skeletal (support, durable, with developed mechanical tissues), growth (rapidly growing, but few branching), sucking (thin, short-lived, intense branching).

2. Zones of a young root

Zones of a young root - These are different parts of the root along the length that perform unequal functions and characterized by certain morphological features (Fig.).

Above is located zone stretching, or heost. In it, the cells are almost not divided, but strongly stretched (grow) along the root axis, pushing his tip deep into the soil. The length of the stretch zone is several millimeters. Differentiation of primary conductive tissues begins within this zone.

Root zone, carrying root hairs, called suction zone. The name reflects its function. In the older part, root hairs are constantly dying, and in young - constantly formed again. This zone has a length of several millimeters to several centimeters.

Above the suction zone, where root hairs disappear, begins zone holdingwhich extends along the rest of the root. It contains water and solutions of salts absorbed by the root are transported to the above plants. The structure of this zone at different parts of it is different.

3. Apical root meristem.

In contrast to the apical meristem of escape, occupying terminal, i.e. End position, apical root meristem subterminalbecause It is always covered with a catering as a thimble. The apicial root meristem is always covered with a cavering as a thimble. The volume of the meristem is closely related to the root thickness: in thick roots it is greater than in thin, but seasonal changes of the meristem is not subject to. In the formation of incidents of the side bodies apical meristem root do not participate, Therefore, its only function is in the neoplasm of cells (histogenic function), subsequently differentiating in the cells of constant tissues. So, if the apical meristem of escape plays both a histogenic, and organogenic role, then the apical rope meristem is only histogenic. The case is also the derivative of this meristem.

For higher plants, several types of structure of the apical meristem of the root, differing mainly, mainly the presence and arrangement of the initial cells and the origin of the hairless layer - risoderma.

In the roots of the horsages and ferns, the only initial cell, as in the oxcea of \u200b\u200btheir shoots, has the form of a threefold pyramid, the convex base of which is drawn down to the cavalry. Dividing this cell occurs in four planes parallel to three side sides and base. IN last case Cells are formed, which, sharing, give rise to the root case. Out of the other cells, they are subsequently developed: protoderma, differentiating in risoderma, primary cortex zone, central cylinder.

Most dysfotical coated-brimmed initial cells are located 3 floors. From the top floor cells called pleroma In the future, the central cylinder is formed, the middle floor cells - periblem Give the beginning of the primary crust, and the lower cells of the case and the protoderma. This layer is called dermakalyptogen.

In cereals, the Oskock, the initiality of which also make up the 3rd floors, the cells of the lower floor produce only the cells of the root case, so this layer is called calipgogen. The protoderma is isolated from the primary bark - the middle-floor derivative initials - periblems. The central cylinder develops from the upper floor cells - plerians, as well as in the bombard.

Thus, different groups of plants differ in the origin of the protoderma, subsequently differentiating in risoderm. Only in disputes of archegonal and dicotyathic, it develops from a special initial layer, in vote and monocycle rhizoderma turns out to be educated primary bark.

Highly important feature The apicial root meristem is also the fact that actually initial cells in normal conditions are divided very rarely, making resting center. The amount of meristem increases due to their derivatives. However, with damage to the tip of the root caused by irradiation, exposure mutagenic factors And other reasons, the resting center is activated, its cells are intensively divided, contributing to the regeneration of damaged tissues.

Primary root structure

The differentiation of the root tissue occurs in the suction zone. By origin, these are primary tissues, as they are formed from the primary meristem of growth zone. Therefore, the microscopic structure of the root in the suction zone is called primary.

In the primary structure, the root differences:

1. Cocery fabric consisting of one cell layer with root hairs - epibline or risodeterm

2. primary bark,

3. Central cylinder.

Cells rizoderma Extracted along the root length. With their division in the plane perpendicular to the longitudinal axis, two types of cells are formed: trichoblasts, developing root hairs, and atrichoblastsperforming functions of cover cells. Unlike the epidermis cells, they do not have thin-walled and cuticles. Treichoblasts are located or groups, their dimensions and form range from different types of plants. Roots developing in water usually do not have root hairs if these roots are then penetrated into the soil, the hairs are formed in large quantities. In the absence of hairs, water penetrates the root through the thin outer walls of the cells.

Root hairs appear in the form of small growth of trichoblasts. The growth of the hairs occurs at its top. Thanks to the formation of hairs, the total surface of the suction zone increases ten times or more. Their length is 1 ... 2 mm, and cereals and enerx it reaches 3 mm. Root hairs are short-lived. The duration of their life does not exceed 10 ... 20 days. After their dying, the risoderma is gradually reset. By this time, the layer of cells of the primary cortex is differentiated into the protective layer - ekoderm. Her cells are tightly closed, after the fear of the risoderma their walls are trying. It is often tested and adjacent to the cells of the primary bark. The exoderma is functionally similar to the plug, but differs from it the location of the cells: the cork cells formed during tangental divisions of cork cambium cells (fellogene) are located on transverse sections with the correct rows, and the cells of the multi-layer exoderma having polygonal outlines are in a checkerboard. In a powerful developed exoderm, bandwidths often meet with neule walls.

The rest of the primary bark is the mesoderma, with the exception of the inner layer, differentiating in the endoderm, consists of parenchymal cells, most densely located in the outer layers. In the middle and internal parts of the cortex of the Mesoderm cells have more or less rounded outlines. Often the most internal cells make up radial rows. Interclatures arise between cells, and some aquatic and marsh plants are rather large air cavities. In the primary crust of some palm trees there are weird fibers, or scleisers.

Classes of the cortex provide risoderma with plastic substances and themselves are involved in the absorption and conducting substances that move both through the system of protoplasts ( symplast) and through the walls of the cells ( apoplast).

The most inner layer of the crust - endodermawhich performs the role of a barrier controlling the movement of substances from the bark in the central cylinder and back. Endoderma consists of tightly closed cells, slightly elongated in the tangental direction and almost square in cross section. In the young roots of its cells have a belt of cappar - sections of the walls characterized by the presence of substances chemically similar to subverin and lignin. Caspari belts are encircled transverse and longitudinal radial walls of cells in the middle. The substances that are deposited in the cappar belts close the holes in these places of plasma-beam channels, but the syllastic connection between the endoderma cells at this stage of its development and cells adjacent to it from the inner and outside parties are preserved. In many two-colon and gone plants, the differentiation of the endoderm usually ends with the formation of cappar belts.

One-bedroom plants that do not have a secondary thickening, over time, the endoderma changes. The process of the testing applies to the surface of all the walls, the radial and internal tangental walls are strongly thicken, and the outer is almost not thicken. In these cases, they talk about horseshoe thickens. Thickened cell walls subsequently decisive, protoplasts die away. Some cells remain alive, thin-walled, only with the capping belts, they are called bandwidth. They provide the physiological relationship between the primary bark and the central cylinder. Typically, bandwidths are opposed to xleery.

Central cylinder rootconsists of two zones: pericyclic and conductive. In the roots of some plants, the inner part of the central cylinder is a mechanical tissue, or a parenchyma, but this "core" is not homologous to the core of the stem, since the compounds of its fabrics have a progonbial origin.

Pericycle may be homogeneous and inhomogeneous, like many coniferous, and from dicotyathic - in celery, in which there is anchogenic semi-sewage selection. It can be one-layer and multi-layered, like a walnut. Pericycle is a merysh, as it plays the role of the root layer - the side roots are laid in it, and the cornerotrapry plants are apparent kidneys. At bombing and gone plants, he participates in the secondary thickening of the root, forming Fellogen and partly Cambier. Cells will last the ability to divide.

Primary root conductive fabrics make up a complex conductive beam, in which the radial cures xylems alternate with groups of floem elements. His education is preceded by the clarification of the central tight. Differentiation of pronambia cells into the elements of the protofloam, and then the protoxizes begin on the periphery, that is, Xylem and Floem are laid by Exarfo, in the future these fabrics develop a centripently.

If one sealers are laid and, accordingly, one chicken floema, a beam is called monarchous (such bundles are found in some ferns), if two chickens are diarrhea, as in many two-colon, in which there may also be tri-, tetra and pentar bundles, and At the same plant, the side roots on the structure of conductive beams may differ from the main one. The roots of monocoons are characterized by polyar bundles.

In each radial heavy xylem inside from the elements of the protoxable, more wide-level elements of metaxema are differentiated.

The formed sealer xilee can be rather short (iris), the inner part of the pumping in this case is differentiated into the mechanical fabric. In other plants (onions, pumpkins) xylem on transverse sections of the roots, there has a star outline, in the very center of the root there is the most wide-level vessel of Metaxema, from it the rays are departed by the trenches of which are gradually decreasing from the center to the periphery. In many plants with polyar buns (cereals, sources, palm trees), the individual elements of the metax cells can be scattered throughout the transverse cross section of the central cylinder between the parenchymal cells or elements of the mechanical tissue.

Primary Floem, as a rule, consists of thin-walled elements, only in some plants (beans) develop protofloem fibers.

The secondary structure of the root.

At one-bedroom and fernant-like primary structure of the root remains throughout (their secondary structure is not formed). With an increase in the age of single-bedil plants, the root occurs changes in primary tissues. So, after the email to the epiblomas, an exoderma becomes a coating tissue, and then after its destruction, - sequentially layers of cells of mesoderm, endoderm and sometimes pericycle, the walls of the cells of which are tracked and decisive. In connection with these changes, the old one-barrel roots have a smaller diameter than young.

Principled difference There are no roots between the vicered, dicotyathic and monocotyledonic plants on the primary structure of the roots, but in the roots of dwaround and gymnos, Cambier and Fellogen are raised early and the secondary thickening occurs, leading to a significant change in their structure. Separate areas of Cambia in the form of an arc arise from pronambia or thin-walled parenchymal cells on the inside of the lights of flora between the rays of the primary xylema. The number of such sites is equal to the number of rays of primary xylems. Pericycle cells that are against the heavyness of the primary xylem, sharing in the tangental plane, give the beginning of the Cambia sitting, closing his arc.

Usually before the cambium appeared pericyclic origin of the Cambia arc begin to postpone the cells that are differentiated into the elements of secondary xylems, first of all, broad-wave vessels, and the outflow of the secondary floema elements, moving to the periphery of the primary flolam. Under the pressure of the formed secondary xylem, cambial arcs are straightened, then become convex, parallel circles of the root.

As a result of Cambia's activities outside of the primary xylema, collateral bundles differ from typical collateral beams, differ from typical collateral beams with lack of primary xylems in them. Cambiers pericyclic origin produces parenchymal cells, the combination of which is quite wide rays, continuing primary xylems, are primary core rays.

In roots with the secondary structure of the primary bark, as a rule, no. This is due to the embedding in the pericycle throughout its circumference of the camp cambium - fellogene, separating with tangental division of the cork cell (falevlems), and the cells of the falevoderm. The impermeability of the tube for liquid and gaseous substances due to suberring the walls of its cells and is the cause of dying the primary bark, which loses physiological communication with the central cylinder. Subsequently, it appears gaps and it falls down - the root melt occurs.

Felleoderm cells can be repeatedly divided into the periphery from the parenchymable zone conductive to the tissues, in the cells of which spare substances are usually postponed. Fabrics located in Kambia (Floem, Basic Parenchima, Felleoderma and Cork Cambium) are called secondary Korea. Outside the roots of dietary plants, having a secondary structure, covered with a plug, and the crust is formed on the old roots of the trees.

Similar information.

- These are the vegetative organs of higher plants, which are underground and carry out water with dissolved minerals to the above-ground organs of plants (stalk, leaves, flowers). The main function of the root is fixing the plant in the soil.

The root is divided into the main, side and apparent. The main root grows out of the seed, it is most powerful and grows vertically down (1st order root). Side roots depart from the main (2nd order roots) and repeatedly branched. Applying roots (3rd order roots) are departed from the side roots, which never depart from the main thing, have a variety of structure and can be formed on stems and leaves.

The combination of all roots of the plant is called - root system. There are two types of root systems - rod and urine. IN santneva root system is greatly expressed by the main root, and urine It consists only of pressing and side roots, the main root is not expressed. Roots in the root system differ in appearance, age and performed functions. The thinnest and young roots are mainly carried out by the function of growth, water absorption and absorption of nutrients. Older and thick roots are fixed in the soil, moisture and nutrients into terrestrial plants. In addition to typical roots, some plants have modified roots, for example, thickened inventory, air, respiratory or reference. As conventional splashing roots are root roots (carrots, beets, parsley), if the supplies become apparent roots, they are called cornklubnia.

Along with roots under the ground, modified shoots may be. Depending on the structure and the functions performed, they are called rhizomes, columns, tubers and bulbs.

Row - These are underground shoots growing mainly horizontally to the soil, less often vertically and performing stocks and vegetative reproduction functions. Rhizome externally similar to the root, but has a fundamental difference in inland structure. On the rhizomes in places called nodes, apparent roots are often formed. After a certain period of growth under the ground, the rhizomes can go to the surface and turn into escape with normal green leaves. Live rhizomes from several to 15-20 years.

Counters - These are underground shoots, at the end of which tubers, bulbs develop, socket shoots. The column performs the function of vegetative reproduction and lives only one year.

Tuber - This is a thickened underground escape that has stocks and vegetative reproduction functions. The tuber has stubborn kidneys.

Bulb - This is a modified underground escape, less often a semi-submarine or shortened above-ground escape, in which the fleast function took over thickened fleshy leaves (scales), and the stem is represented only in the lower part of the bulbs in the form of a flat education - a dona from which the apparent roots grow. The bulb ensures the preservation of moisture and nutrients for the time of the winter or summer period of rest of the plants. After the rest period, the plant is usually blooming using stocks accumulated in bulb.