Seeds in plants arose as a result of a long evolution process as an organ, most reliably ensuring their distribution.

The main part of the seed - germ future plants. It consists of a stuffed stalk, from which the root of the leaves and the roots depart. At the top of the stem is kidney. The first leaves of the embryo, usually sharply different from the subsequent structures and the function, are called seedlings. Plants whose seed has a pair of cotydons, belong to the class of two-colon (peas,, flax, hemp, cabbage, etc.). If only one seedle is available in the seed, then this is a single-barrel plant (Iris, Lily,, and others).

In the seed, the supply of nutrients is necessary for germination, which is either in the germ itself, or in a special sparkling seed fabric. Outside the seed is protected by peel. These plants like beans, peas, pumpkin, the seed consists of peel and the embryo. Peel protects it from drying and damage. Under the leather is the embryo. Most of the embryo falls on cotyledons, which contain spare nutrients (, fats, carbohydrates). Sejdoli is modified leaves. Between them there is an embryonic root, skelter and tieney (. 18, l).

endosperm

Terms of germination of seeds

18, l).

Fig. 18. The structure of the seed. A - bean seed; B - seed (grain) Wheat: 1 - Kindle, 2 - Hirelessness of the embryo, 3 - Steel 4 - Fur, 5 - Semi-silder, 6 - shield (Semi-Deedole), 7 - endosperm

In the seeds of other plants, nutrients are postponed in a specialized inquiry tissue - endosperm. An example of seeds with endosperm can serve as seeds of bread cereals. Under the leather of their seed, the endosperm and germ (Fig. 18, b) diffuses. In the embryo with the help of a magnifying glass, you can consider the only seedlist - the shield, the embryonic root, skelter and kids. With germination of the grain, the endosperm nutrients are absorbed by the cells of the shield and are used as an embryo. Endosperm contains starch and vegetable protein - gluten. Minerals and water also includes seeds. Waters in dry seeds contain 6-14%, minerals - 2-4%.

The seeds necessarily include various enzymes. With their help, there is a conversion of seed spare substances into a digested form for the formative embryo.

Terms of germination of seeds. For germination of seeds, water is needed, air and warm. Water penetrates under the peel of the seed through a small hole, called the semi, with the result that the seed swells. The need for swelling is primarily dependent on the composition of the seed. Seeds rich in fats are absorbed by 30-40% of water rich in starch - 50-70%, seeds with a large amount of protein - about 90% of water. Water is also needed to dissolve the nutrients of the seed, which are absorbed by the growing germs of the seed.

Seed swelling is accompanied by intensive enzyme activities. Spare nutrients in the seeds are in the sedental forms of complex organic compounds. In order for solid polysaccharide starch to be used in the embryo, it is necessary to hydrolyze it under the influence of the diastase enzyme, which precipitates the starch to the maltose soluble Disaccharide. Other substances dissolve under the action of other groups of enzymes. Dissolved and movable decomposition products can already be used germs. During the decay, the energy is released, which goes on the strengthening of the physiological functions of the seedlings.

Figure 19. The germination of the bean seed (A, B, B, Various Stages): 1 - Main root, 2 - Sliced \u200b\u200bKnee, 3 - Supersiyadole Knee, 4 - Semilyti, 5-First Leaves, B - HUMAN

During the rest, the breathing of seeds is very weak, but during germination, the need for oxygen increases sharply. Seven seeds not only absorb oxygen, but also isolated carbon dioxide, i.e. breathe. This is natural: because plants, like animals, are living organisms. During breathing, heat is highlighted. Raw seeds breathe vigorously dry. Therefore, they are quickly heated with a thick layer and, as they say, "burn", and their embryos die. Seeds become nonsense. They are removed for storage only dry and stored in dry, well-ventilated rooms, while air access to seeds should be free and permanent.

Seeds can be generous only at a certain temperature: for example, winter rye at 2-4 s, and the seeds of cucumber - at 15-16 ° C. The heat demanding plants are sown later when the soil warms up.

Swords. Young rabes who develop from the embryo seed are called seedlings (Fig. 19). The first time the seedlings feed on spares accumulated in the seed. If Seidoli is taken over the soil during germination, this type of germination is called overhead (for example, cucumber, pumpkin, beans, carrots). In the case when Seidoli remain underground, germination is called underground (peas, oak, wheat,).

The seedlings of monocycle plants are usually several roots (in winter wheat - 3, yarova - 5). The seedlings of two-colors first, as a rule, one root is formed, which then branches.

The structure of seeds of dysfotrol plants

White Cle Seed (Acer Pseudoplatanus) in the context - visible germ

w: Seed is a stuffy plant that develops from a nephery. The size of the seed can be different - from 0.001-0.003 mg (orchid and infected) to 20 kg (seeded of Seychelles palm).

Germination of bean seed

Beans - Dichildo Plant. Her seeds are large. One of the sides of the bean seed is convex and smooth, the other side is concave and the Rubber is visible on it - this is a trace of seeds. The seed seed was attached to the ocoloblodnik. The seed is covered with a brilliant smooth seed peel, which protects it (seed) from mechanical damage and severe drying. The peel of the bean seed can have a different color.

Seed peel is a structure outside the covering and protecting the embryo in seed from the oversaturation of moisture or drying.

Under seed skin is a germ consisting of two cotyledons and the root, stalk and kidneys located between them, which can only be considered through the magnifying glass. Semilyts - large and thick, they contain a supply of nutrients. The structure of most seeds of other plants is approximately the same. But there are also differences. For example, the buttercup and violet germs are surrounded by endosperm cells, which contain an additional supply substance. Therefore, their seed peel surrounds not the embryo, but endosperm.

Singlean Plant Seeds

Grain Rzya

Seeds of monocotyledonous plants (for example, bread cereals) have a different structure. Dry fruits of cereals - grains. Outside the grain is dressed in the golden-yellow leathery. He so tightly processed with seed peel that it is impossible to disconnect them.

Egg on a seed section of the Ginkgo Two-Biloba (Ginkgo Biloba)

Most of the grain occupies torment endosperm. This can be seen by cutting the grain along. Endosperma cells contain nutrients.

Endosperm is the fabric formed in the seeds of most flowering plants during fertilization. Endosperm surrounds the embryo and provides its nutrition at the expense of starch, vegetable oils and proteins. This makes endosperm of flowering plants an important source of nutrients in a person's diet.

The embryo at the grain is so small that only under the magnifying glass can be considered. The embryo has a root, skelter and tieney. He has one seedlings, it does not contain nutrients, thin, fits tight to the endosperm. It was through the seedlighter during the germination of the seed to the germin from the endosperma comes with nutrients. Monocotionals call plants whose embryos have one seedlings.

Other monocoan plants, seeds also have endosperm, which surrounds the embryo, unlike the endosperm of cereals, where endosperm is adjacent on one side.

Composition of seeds

Seeds are characterized by a certain chemical composition, which depends on the biological features of the type and variety, power conditions, age, temperature, etc. All seed substances can be divided into two groups: inorganic and organic.

Inorganic seeds are represented by water and minerals. Even the dry of the seeds contain from 7 to 12% water. This can be seen, heating seeds in the test tube. At the same time, water drops will be formed on the walls of the test tube. When burning seeds, an ash remains, which is a mixture of various mineral salts.

Seeds of all plants contain organic substances - proteins, fats and carbohydrates. However, their percentage content in seeds of various plants is not equally. In the seeds of some plants, a large amount of starch accumulates (wheat 66%, rye is 67%), in others - fats (in flax up to 48%, in Kleschevina to 70%), in third - proteins (in pea - 22-34 %, Soy - 34-45%). In any case, in a larger or smaller amount in the seeds contain all organic matter.

Breathing seeds

Seeds, like other living organisms breathe, that is, absorb oxygen and distinguish carbon dioxide. Breathe seeds around the clock, highlighting warmth. It warmly heats them. Especially many heat excrete germinating seeds. Wet sprouted seeds breathe more vigorous than dry non-sore. If you fold the thick layer of wet breakdown seeds, they will quickly warm up. Their embryos die, and as a result, the seeds lose their germination. Therefore, it is necessary to store seeds only dry in dry ventilated rooms. Permanent air access is necessary for dry seeds, even though they breathe and weaker germinating.

Nutrition and height of seedlings

Sprouted wheat grains, barley or rye are slightly sweet. This is because during the germination of seed starch, which is contained in endosperm, is converted to sugar (under the action of some substances). Sugar is soluble in water, and its solution flows to the germin and nourishes it. The cells of the root, stalk and kids, of which the germ consists are divided, feeding with a solution of sugar, and in the end turn into a seedlings.

At first, the germ of the germinating seed is powered by reserves of substances in the cells of the endosperma or the embryo. The more these substances are postpted, the stronger the seedlings will be. It consumes these nutrients during its growth. For sowing only full, large seeds. Without a cotyledon or without an endosperm, the embryo will not be able to grow into a healthy seedlings and most likely will die. Therefore, the seed should be whole.

During the germination of the seed, the root appears first. He is ahead of other bodies in development and is rapidly strengthened in the soil. For the roots, the seedlings can be determined by a single-barrel or dicarological plant germinals from the seed. Usually, the seedlings of monocotyledonic plants develop several roots at once, and two root crumbles, then it begins to branch.

Sowing time and seed sealing depth

Determine the time to dry seeds must be given the conditions necessary for their germination. Seeding seeds are needed water, air and warm. Only seeds of cold-resistant plants can be heated in early spring (wheat, peas, oats, barley), germinating at low temperature and abundance of moisture. Because at this time in the soil accumulates a lot of melt and rainwater, but the soil has not yet managed to warm too much.

Severy seeds of thermo-loving plants (corn, beans, cucumbers, tomato, melon, pumpkin) It is necessary when the sun warms the soil well enough. But it is also impossible to slow down, because from the abundance of heat heat dries. Location with sowing heat-loving seed will reduce the crop. It is necessary to sow seeds of thermo-loving plants as soon as the soil warms up to 10-12 ° C.

When sowing seeds can be other errors. Seeds can be sown in a timely manner, but not enough to deeply close them in the soil. So they dried under the sun. And if the seeds, on the contrary, close in the soil too deep, then shoots will be bad. Deep under the ground, the seedlings do not have enough air, and young shoots will be difficult to break through the surface.

Seeds must be burned to a certain depth, given their size and soil properties. It is necessary to sow large seeds. In such seeds there are enough nutrients in order to make their way from great depths during a long time.

Small seeds, such as the seeds of the turnips and onions, must be sowed to a depth of 1-2 centimeters. Seeds of more sizes (radishes, cucumbers) - at a depth of 2-4 cm. Large seeds of beans, peas or beans can be sown to a depth of 4-5 cm. If such large seeds are not so deep, then they do not have enough moisture.

The structure of the soil also matters. For example, clay soil is dense and heavy, even very close to the surface in it there is little air, and moisture is enough in the upper layers. Therefore, the seeds are not recommended too deep into such a soil.


.(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.)

seed

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


Synonyms:

Watch what is "seed" in other dictionaries:

    Cf. The substance containing an embryo animal or vegetable. From the seed tree, from the tree fruit, from the fetus seed. What is the seed, such and the tribe, and vice versa. Everyone has been brought from our seed. | Descendants, downward generation. All, Yako Seed ... ... Explanatory dictionary of Daly

    Seeds of coagovic large. Elliptical, oval egg-shaped or spherical in shape, they usually have a length of 3 4 cm with a thickness of 2 3 cm. But individual species have or smaller, or larger seeds. So, the seeds of the zami ... ... Biological encyclopedia

    Seed, genus. and dates. Seed, Semen, Seed, MN. Seeds, seeds, cf. 1. Plant breeding organ, grain from which a new plant is developing. Seed develops from a seed. In the core of the seed is the embryo. The plant gave seeds. Selection ... ... Explanatory Dictionary Ushakov

    Grain, bone. Cm … Synonym dictionary

    Modern encyclopedia

    In Botanic, the reproduction body, resettlement and experience of adverse conditions in seed plants. Developed from a seedwork, usually after fertilization. In the seed distinguish the embryo, the peel (shell) and many plants with spare ... ... ... Big Encyclopedic Dictionary

    Seed ... The initial part of the complex words, which makes the meaning of the word: seed 1., 4. (seeding, seeds, seedup, etc.). Explanatory dictionary Efremova. T. F. Efremova. 2000 ... Modern explanatory dictionary of the Russian language

    Seed - (Botanical), the reproduction body and resettlement in seed plants. Developed from a seedwork, usually after fertilization. In coated plants, the seed is imprisoned in the fruit, the gamotors are formed openly on seed scales and ... ... Illustrated Encyclopedic Dictionary

    Seed, part of flowering plants (coated brine) containing germ and nutrition reserves. It is formed in the ovary by fertilizing the female gamete. Nutrients can be stock in a special fabric called endosperm, or ... ... Scientific and Technical Encyclopedic Dictionary

    Seed, Meni, MN. Mena, Monga, Menam, Wed. 1. The organ of breeding in plants, grain. Hemp with. 2. MN. Severe, intended for sowing. Surgeted seeds. Leave a plant for seeds (to get seeds from it for sowing). 3. Intr., which. ... ... Explanatory dictionary of Ozhegov

Seed - Effective plant. It develops from the seminal. In the structure of the seeds of dicotyledonous and monocotyledonic plants differ in each other. Outdoor plants have one of the sides of the seed convex, the other concave. Outside a brilliant smooth seed peel. Under it - a germ consisting of two cotyledons and the root, stalk and tieney located between them.

Seed The single-bedroom outside is dressed in an oily township that fits tightly with seed peel. If the seed is cut, you can see that most of the muddly endosperm, the embryo has a little root, skelter and tieney.

After the rest period, his germination begins. For the germination of the seed, certain conditions are necessary. For seeds of each type of plant, these conditions are different. Temperatures in which various seeds can germinate, range from +5 to +40 degrees C. The germinating seed is actively breathing.

Prerequisite condition - the presence of water. In the first stages, to the development of the leaves, the embryo is powered by an exclusively in the supply of nutrients. This is mostly lipids, proteins. The growth of the proprietary itself is due to cell division and increase their size. The first visible sign of germination is the appearance of the primary root. It possesses primary geotropism, that is, it grows in the direction of gravity, rooting the plant in the ground.

Having pleased us at the flowering stage of the richest palette of tones, shades, a variety of forms, causing amazing images in the imagination, plants enter the next stage of development - the formation of seeds that will continue their lives in the following generations.

Is it possible to call the seed organ organ? It turns out no. Even the first cell formed by the merger of the nuclei of pollen grain and egg cell is already a new organism, although depending on the parent plant at the initial stages of its development.

The structure and properties of the seed are determined by the main functions entrusted to them by nature: Plant reproduction, resettlement and experience of unfavorable conditions. The ability of the seed is optimally implemented by these functions depend on both the genetic potential of parents and the conditions in which the parent plant has grown. The agronomists even have the concepts of germination of seeds (the ability to give friendly shoots) and germination (the proportion of sprouted seeds from the total number of planted). These characteristics talk about the quality, the "strength" of seeds.

The seeds are surprisingly diverse on the external structure, in size, by weight, in the composition of spare nutrients and even by the degree of formation of the embryo to the point when they leave the parent plant. Common for all seeds is that they consist of seed peel, endosperma (nutrient stock) and the embryo.

Protection of the embryo provides seed peel. It is impenetrable for water; Such seeds can lie in the soil for a long time before germinate. In addition, when the seed is ripening, abscusing acid is accumulated in its peel, overwhelming metabolic processes.

A mature embryo has a sterep-like axis carries one or two semi-siardolis (the first "leaves" of the future plant). At the ends of the germinal axis, the assessed meristems of the root and escape are located.

The main function of the endosperma is to feed the germination germin.

Like the embryo, endosperm consists of living cells. But why a plant is a living inlet tissue?

Endosperm is not just a storeroom. Here the program of admission to the germinating germ of nutrients is recorded: what connections need to be issued and in what order.

In seeds of different plants, endosperm is developed to varying degrees. It constitutes the main part of mature wheat seeds, tomatoes, carrots. And the cherry, pea, sunflower it is almost not developed; Reserves are concentrated in the germ itself, most often - in the seedy leaves (in legumes).

Endosperma orchids are not completely, and the microscopic germ also does not contain spare substances.

To germinate, the seed of orchids should get into rich and wet soil, penetrated by mycelium mushroom risoctones. With this symbiount, the seedlings get everything necessary until it becomes possible to independently existence.

And what plants are in store in seeds? The cereals, for example, accumulate in endosperm starch. Its quite a lot - 60-70% of the dry grain mass. Proteins in these seeds are only 10-16%, fats - 2%. Bean plants are mainly equipped with proteins: soy - up to 40%, peas, beans, vica - up to 30%, beans - 23%. Seeds of oilseeds contain a lot of fats: Kleshchenina - 60%, Sunflower - 56%, sesame - 53%, Mac - 45%. Different seed composition implies different paths of further transformation of stocks.

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Development of the pollen tube. Dusting, hitting the pistil on the stil, germinates. The contents of pollen, dressed as an intine, is pulled through the pores in the exine and forms a pollen tube. The growth rate of the pollen tube is 35 mm / hour

The core cells and the generative kernel are on the growing end of the pollen tube. Having reached the ovary, the pollen tube is sent to the selection and penetrates it through the micropile. The shell of the germ bag is dissolved when contacting the tip of the pollen tube. In the embryonic bag, the pollen tube grows towards the egg. The shell on the tip of the pollen tube bursts and from there are two sperm. One merges with an egg, and the other - with the secondary germ sac core or with one of the central nuclei. Double fertilization occurs - a characteristic feature of coated plants, not occurring from the vicered. Double fertilization opened in 1898. Russian Botanist S. G. Navashin.

Subsequently, germ develops from the fertilized egg, and from the tubular cell with a fertilized secondary kernel - endosperm. Endosperm coated bridges trioloid, which is a fundamental difference between coated bridge and viced.

In the form of sperm different: rolling-shaped, worm-shaped, capable of moving, despite the absence of flagellas ..

The formation of the embryo. The fertilized egg is moving into the state of peace, depending on time and external conditions. The first division is accompanied by the attachment of the transverse partition. A germ develops from the terminal cell, and the cone of the increasing of escape and Semilytoli is formed from the basal cell. The primary root occurs from the lower cell of the suspension. In bicycles, the germ has two semilaries, the sumps, the primary root, the cone of the increasing of the primary escape (sometimes the rigging leaves or risening are formed).

Formation of endosperma.

What is the germ of the plant seed? The structure of the embryo semen

Endosperm serves as the main source of nutrients

The orchid development of endosperma is suppressed. The triploid core dies off immediately or after several divisions.

The seed turns into the seed. The peel is formed from the integuments, partly from Nomecellus, the wall of the margin forms the ocopulodnik, surrounding seeds, developing in the wound. All marking turns into fruit.

SEED

As a result of the process of double fertilization from the seed, a seed is formed. The seed consists of an embryo and spare nutrients covered with seed peel. The germ of the seed develops from the zygotes formed by the fusion of sperm with an egg. The cell resulting from the merger of another sperm with the secondary nucleus of the germ bag is developing into the nourishing fabric of the seed - endosperm. Synergies and antipodes are usually degenerated and dissolved, the integuments turn into the seed peel, and the majority of the majority

Fig. 117. Covenate seeds. A-with endosperm, which surrounds the embryo (MAC); B - with an endosperm that lies next to the embryo (wheat soft); B - with spare stuffed in semi-units of the embryo (peas); G - with endo-sperm surrounding the embryo, and powerful perisperm (black pepper); D - with pericorial, surrounded by germs (kudz);

/ - Seed peel, 2 - seed peel, fragile with pericarpium, 3-perisiserm, 4 - endosperm, 5 - germin, 6 - Humming, 7 - Fur, 8 - Semi

plants are consumed directly in the composition of the nutrient in the formation of the embryo of the seed, less often turns into a nutrient tissue - perisperm.

There are four types of seeds depending on the side of where spare substances are laid: in endosperm, in the perisperm, in a child, in endosperm and perisperme (Fig. 117).

Consider more detailed seed structure with endosperm On the example of wheat grain, representing a fruit with one seed (Fig. 118). Outside it is covered with a rather thin film layer, which is difficult to separate from the inside of the grain. This layer is an airlodic, sneaking-busy with seed peel. Inside the proposed germin and endosperm. The embryo has a formed vegetative organs of the bu-blowing plant: the embryonic root with a root case, the root vagina - the flavor, the embryonic skeleton and kids. In the center of the kings, the cone on-polling the stem, covered by embryonic leaves, is well noticeable. Upper germ sheet - Koleoptil - serves as protection for the young seedling when passing through the soil. A part of the embryo, adjacent to the endosper, is called a shield. The shield is the only developed semi-deeder, which performs the function of absorption of nutrients from the endosperma during the period of germination of semes. On the opposite shield, the side of the stelee is epiblast - probably OS-TOOT (Rudiment) of the second semi-syedoli. Many cereals are missing. The endosperm in the peripheral part (under the seed co-magazine) has a layer of homogeneous cells, co-holding alarium grains, is an alaron-low layer, starchy cells are located in the central part.

Example seeds with spare substances in the embryo There can be seed of beans (Fig. 119). Outside it is covered with pretty thick seed peel. On the narrow vein-that surface of the seed is the rub-chic - the place of attachment of the seed to the seed-leg. Here is the micropylene (ce a ditch). Its role is in passing the batteries and gases inside the seed. Directly above the micropyle is placed a small bogo-rock formed by an embryonic root.

Figure 118. Wheat grain. The scheme of the longitudinal transverse section;

B-embryo on the longitudinal section: 1-hairs, 2-olt-camplodnik, 3-pea seed pea, 4,5-endosperm, 6-shield, 7-skelter, 8-respect, 9list, 10-collaptile, 11-epiBlast, 12- Fur, 13-cable, 14-ocherism (root vagina).

Seeds are characterized by a very important feature: in conditions of malicious-pleasant for germination, they can be a considerable time to be in a state of deep peace.

With the onset of favorable conditions (temperature and humidity), the seeds absorb water and with sufficient air access begin to germinate, forming the seedlings.

Seedit develops from a severity after fertilization (in the case of apomixis - without fertilization). Outside, it is covered with seed peel formed from the integment and performing a protective function. Endos perm, which appeared from the triploid nucleus, contains spare substances, pending germ during germination. In some plants, a sparkling function can perform the perisperm formed from the nicknole. From the op-lifted egg, the embryo is developing.

Seeds of many plants have appendages in the form of juicy, fleshy, often colored growth rich in nutrients. If these growing are developing from seeds (passiflora, eavesklet, nutmeg), they are called sediments, or aryllas, if from the integuments (stitching, meltoven) - karunkulaum, or arylloid. They serve to attract animals involved in the spread of seeds.

Seed peel (sperm) performs a protective function. The peel is a small hole - micropyl, contributing to the penetration of the first portions of water at the beginning of swelling, and the Rubber is the place of attaching a seed to the seed. Degree of development, the hardness of the seminal peel is determined by the nature of the octalummate: with unbroken solid spindles, it is thin (cherry, oak, composite); In the opposite cases of peel solid (grapes, Kalina). Pomegranate has a juicy seed peel.

Endosperm arises from the triploid nucleus, which after fertilization begins to share the first. According to the nature of development, three main types of endosperma are distinguished:

  • nuclear (nuclear), i.e., a large number of nuclei is formed, then shells are formed around them;
  • cellular (cellular), i.e., each division of the core is accompanied by cytokinesis;
  • gelobial (intermediate), i.e., after the first division, the embryonic bag is divided into two parts: micropilar (greater) and chalazal (small). They have a free division of the nuclei, and the cell walls appear later.

Starch, oils, squirrels are stamped in endosperm. In the resting seed endosperm solid. In germination, the endosperm substance is hydrolyzed under the action of enzymes and absorbed by the embryo; 85% of coated plants have endosperm (magnolia, lily, palm trees), 15% do not have (legumes).

Perisperm is a flat fabric characteristic of some plants (pepper, water lily, star, beet) and emerging from the niculus (2N).

The following types of seeds are distinguished by the preserving tissues:

  • with endosperm (Kleshcheng, cereals, grated);
  • with endosperm and perisperm (pepper, water lily);
  • with perisperm and without endosperma (star, dock, beet);
  • without endosperma and perisperm (legumes, orchid).

The embryo arises from the fertilized egg and consists of meristematic tissues.

The overall structure of plant seeds and the necessary conditions for germination

Heterotrofen is often dissected. The germ is represented by the axis and seedy leaves (two - in two-bedrooms, one - in one-bedroom). Semi-units perform excretory, stocking, suction functions.

On the axis of the embryo, some plants have a kidney with the meetings of real leaves. On the other hand, there is a root with root case. A part of the axis to which Semilytoli is attached is called a seedlined knot. Below the seeds on the axis is the hypocotyl (sampled knee), above - epicotyl.

In the seed of cereals, endosperrum occupies a significant amount, since there is spare substances in it. It is differentiated by two layers. A-rug - alarium layer in which proteins are deposited. It is located immediately under seed skin. Closer to the center there are cells with the collapse grains.

The embryo of cereals consists of one cotyledtoli, an embryonic root, an embryonic stalk and kids. The only semilar (shield) goes to a well-developed endosperm. In the center of the hirelessness, the cone of the rise of the stem, covered by the priority of the leaves. The outer capid sheet surrounding the kidney is called a collaptile. The embryonic root is surrounded by a special multi-layer case (oloriza), which swells at germination and develops suction hairs on the surface. Sometimes on the side, the opposite of the shield, the scratch-shaped grown is formed - epiblast. He is regarded by some scientists as the rest of the second semilar

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Seed - plant reproduction body, developing after fertilization from a nephery.

In the formation of seed and fetus, one of the sperm merges with an egg, forming diploid zygot (fertilized egg). In the future, the zygotes is expanding repeatedly, and as a result, a multicellular embryo plant is developing. The central cell, which fastened with the second sperm, is also repeatedly divided, but the second embryo does not occur. A special fabric is formed - endosperm. Endosperm cells accumulate nutrient reserves required for the development of the embryo. Child covers grow and turn into seed peel.

Thus, as a result of double fertilization, a seed is formed, which consists of an embryo, a flat tissue (endosperma) and seminal peel. The wall of the fetus is formed from the wall of the waters, called the ocoplodnik.

Types of seeds

1. With endosperm (the seed consists of three parts: seed peel, endosperm and embryo. Seed with endosperm is inherent in single-grade, but can occur in dicotyledtic - poppy, grated, umbrella);

2. With endosperm and perisperm (usually a rare type of structure, when the seed is germin, endosperm and perisperm. It is characteristic of the lotus, nutmeg);

3. With perisperm (endosperm is fully spent on the formation of the embryo. Seeds of this type are characteristic of cloves);

  1. without endosperma and perisperma (the embryo occupies the entire cavity of the germ bag, and the spare nutrients accumulate in the semi-units of the embryo. Together, the seed consists of two parts: seed peel and the embryo. Such a structure is peculiar to bean, pumpkin, rose, nut, bukov, etc.)

Perisperm - stocking diploid cloth of the seed in which nutrients are laid. Arises from the nomalus.

Endosperm - Large-milking Flashing fabric, main power supply for developing embryo. At first, he actively conveys the germ of the substance coming from the parent organism, and then serves as a tank for laying nutrients.



Fig. Seeds

16. Classification of fruits. SPLATE .

The fruit of the reproduction of the coated bridges, which is formed from one flower and employee for the formation, protection and distribution of seeds in it. Many fruits-valuable food, raw materials for drugs, coloring substances, etc.

Classification of fruits

In most classifications, fruits are usually divided into real(Forming from the outstanding promise) and false(Other organs participate in their education).

Real fruits are divided into simple (formed from one pistil) and sophisticated (arising from the polynomial of the apocarpical guinesey).

Simple divide on the consistency of the octopulodnik on dry and juicy.

Among dry distinguishes single-seat (for example, a grain, walnut) and multispical. Multivine fruits are divided into open (bob, box, bag, pod, etc.) and unbroken. Invisible dry multifreemary fruits are divided into segic (segmenty bob, segmental pod) and fractional (tubing, double-straw, etc.)

Among juicy fruits also allocate multi-semen (tsykina, Apple, Berry) and single-stage (Kostyanka).

Complicated are called, based on the names of simple fruits (multicast, multi-perts, etc.).

In contrast to the fetus (simple or complex), the nozzle is formed not from a single flower, but from a whole inflorescence or its parts. In any case, the axis of inflorescences participate in the formation of the hodge. The nozzle is a product of modification (after fertilization) not only flowers, but also the axes of the inflorescence. In typical cases, the nozzle imitates the fruit and matches it functionally. Classic example - pineapple hoping.

17, vegetative reproduction of plants and its biological Value of vegetative reproduction of plants(from lat. vegetativas. - Vegetable) is the reproduction of plants with the help of vegetative organs (root, stem, sheet) or their parts. Vegetative plant reproduction is based on regeneration phenomenon. During such a method of reproduction, all properties and hereditary qualities in subsidiaries are fully saved.

There are natural and artificial vegetative reproduction. The excellent reproduction occurs constantly in nature through the inability or difficulty of seed reproduction. It is based on the separation from the parent plant of viable vegetative organs or parts capable of regeneration to restore a whole plant from its part. The whole combination of the individuals thus obtained is called clone. Clone(from Greek. CLON - sprout, branch) - population of cells or individuals, which is formed as a result of the forgeless division from one cell or individual. Vegetative reproduction of plants in nature carried out by:

Separation (single-cell);

Root sprouts (cherry, apple tree, raspberries, blackberry, rosehip);

Korebolbami (orchid, dahlia);

Messengers (currants, gooseberry);

Mustache (strawberries, sludge creeping);

Owls (drink, reed);

Tubers (potatoes);

Bulbs (tulip, onions, garlic);

Brood kidneys on the leaves (broofіlyum).

Biological importance of vegetative reproduction:a) one of the devices for the formation of descendants where there is no favorable conditions for sexual reproduction; b) the descendants are repeated by the genotype of the parent form, which is important to maintain signs of the variety; c) one of the ways to maintain valuable varieties and properties; d) with vegetative reproduction, the plant can be kept under the conditions of impossibility of seed reproduction; e) a preferred method of reproduction of decorative plants; e) When vaccinated - in the submitted plant, resistance to external conditions increases. The following are the shortcomings of vegetative reproduction: a) negative features b) are transmitted to the diseases of the parent organism.

18. Casual reproduction, its role and form Reproduction is a universal property of all living organisms, the ability to reproduce themselves like. With it, it is saved in time of species and life in general. The life of the cells, much shorter than the life of the body itself, so its existence is supported only by the reproduction of cells. There are two methods of reproduction - cull and sex. With a bunch of reproduction, the main cellular mechanism ensuring an increase in the number of cells is mitosis. The parent is one part. The offspring is an accurate genetic copy of the parent material. 1) the biological role of the powerful reproduction maintenance of adaptability enhances the value of the stabilizing natural selection; Provides rapid pace of reproduction; Used in practical selection. 2) Forms of non-cellular reproduction in single-celled organisms allocate the following forms of cull breeding: division, endogonium, sisogonia and binding, spore formation. The division is characteristic of amoeba, infusoria, flagella. First, the mitotic division of the nucleus occurs, then the cytoplasm is divided into half an increasingly deepening hauling. In this case, the daughter cells receive about the same amount of cytoplasm and organoids. Endogonia (internal kinding) is characteristic of toxoplasm. In the formation of two subsidiaries, the maternal gives only two descendants. But there may be an internal multiple binding, which will lead to sizogonia. It is found in disputes (malaria plasmodium) and others. There is a multiple division of the kernel without cytokinesis. From one cell a lot of subsidiaries are formed. Burning (in bacteria, yeast mushrooms, etc.). At the same time, a small tubercle containing a subsidiary (nucleoid) is originally formed on the maternal cell. The kidney grows, reaches the size of the maternal individual, and then separated from it. Spore formation (at the highest spore plants: mosses, ferns, plane, horsages, algae). A child organism develops from specialized cells - disputes containing a haploid set of chromosomes. 3) The vegetative form of reproduction is characteristic of multicellular organisms. At the same time, the new organism is formed from a group of cells separated from the parent organism. Plants are breeding with tubers, rhizomes, bulbs, cornklubs, rootpods, root pigs, tanks, cuttings, broken kidneys, leaves. In animals, vegetative reproduction occurs in the lowest organized forms. The cilia worms are divided into two parts, and in each of them the missing authorities are restored by disordered cell division. Killed worms can restore a whole body from one piece. This type of division underlies the regeneration - restoration of lost tissues and parts of the body (in ring worms, lizards, salamander)

19 sexual reproduction - associated with the merger of specialized genital cells - Games with the formation of zygota. Gamets may be the same and different in morphological terms. Isogimy - merging the same heams; heterogamia - the merger of different Games; Oogamia is the fusion of a movable sperm with a large stationary egg.

For some plants groups, the alternation of generations is characterized, in which the sexual generation produces sex cells (Gametophyte), and the contradianship (sporophyte) is disputes.

Fertilization - this is an association of nuclei of male and female genital cells - Games, leading to the formation of the zygota and the subsequent development of the new (subsidiary) organism.

Gamete - This is a reproductive cell having a single (or haploid) a set of chromosomes involved in sexual reproduction. That is, in other words, the egg cell and spermatozoa are gates with a set of chromosomes of 23 each.

Zygote - This is the result of the fusion of two heams. That is, the zygota is formed as a result of the merger of the female egg and a male spermatozoa. In consequence, it develops into a person (in our case, in a person) with the hereditary signs of both human organisms.

Isogami

If the merging machines morphologically do not differ from each other, the magnitude, structure and chromosomal set, they are called izoatami, or cullless gates. Such gametes are mobile, can carry flavors or be amosides. Isimy is typical for many algae.