Escape is a complex elevated organ of a plant. Escape and escape systems

Or accessory (adventive) kidney. Thus, the kidney is a rudimentary shoot. When the seed germinates from the germinal bud, the first shoot of the plant is formed - its main shoot, or first order escape.

From the main shoot are formed side shoots , or second order shoots, and when branching is repeated - of the third order, etc.

Adventitious shoots are formed from adnexal buds.

This is how the system of shoots is formed, represented by the main shoot and side shoots of the second and subsequent orders. Escape system increases total area contact of the plant with the air.

Depending on the function performed, shoots are distinguished as vegetative, vegetative-generative and generative. Vegetative (unmodified) shoots, consisting of a stem, leaves and buds, and vegetative-generative (partially modified), additionally consisting of a flower or inflorescence, perform the functions of air nutrition and provide the synthesis of organic and inorganic substances. In generative (completely modified) shoots, photosynthesis most often does not occur, but sporangia are formed there, the task of which is to ensure plant reproduction (a flower also belongs to such shoots).

The shoot that produces flowers is called flowering shoot, or peduncle(sometimes the term "peduncle" is understood in a narrower sense - as a section of the stem, on which the flowers are located).

Main escape organs

A vegetative unmodified shoot is a single plant organ, consisting of a stem, leaves and buds, formed from a common array of meristems (the cone of growth of the shoot) and having a single conducting system. The stems and leaves, which are the main structural elements of the shoot, are often considered as its constituent organs, that is, organs of the second order. In addition, the obligatory affiliation of the escape is the kidneys. home external feature that distinguishes the shoot from the root is the presence of leaves.

Monopodial branching

Monopodial branching is the next stage in the evolution of shoot branching. In plants with a monopodial type of shoot structure, the apical bud is preserved throughout the life of the shoot. The monopodial type of branching is often found among gymnosperms, it is also found in many angiosperms (for example, in many species of palms, as well as plants from the Orchid family - gastrochilus, phalaenopsis and others). Some of them have a single vegetative shoot (for example, Phalaenopsis is pleasant).

monopodial plants- the term most often used in the description of plants of tropical and subtropical flora, as well as in popular science literature on indoor and greenhouse floriculture.

Monopodial plants can vary significantly in appearance. Among them there are rosette, with an elongated shoot, bushy.

Sympodial branching

In plants with a sympodial type of shoot structure, the apical bud, having completed development, dies off or gives rise to generative run away. After flowering, this shoot no longer grows, and a new one begins to develop at its base. The structure of the shoot in plants with a sympodial type of branching is more complicated than in plants with; sympodial branching is an evolutionarily more advanced type of branching. The word "simpoidal" is derived from the Greek. sym("together" or "many") and pod("leg").

Sympodial branching is characteristic of many covered seed plants: e.g. for limes, willows and many orchids.

In orchids, in addition to the apical ones, some sympodial orchids also form lateral inflorescences, developing from buds located at the base of the shoot (Pafinia comb). The part of the shoot pressed against the substrate is called the rhizome. It is located, as a rule, horizontally and does not have true leaves, only scaly. A reduced, almost indistinguishable rhizome occurs in many Masdevallia, Dendrobiums and Oncidiums; well distinguishable and thickened - in cattleyas and lelias, elongated - in bulbophyllums and cologins, reaching 10 or more centimeters. The vertical part of the shoot is often thickened, forming the so-called tuberidium, or pseudobulb. Pseudobulbs may be various shapes- from almost spherical to cylindrical, cone-shaped, club-shaped and elongated, resembling reed stalks. Pseudobulbs are storage organs.

sympodial plants- the term most often used in the description of plants of tropical and subtropical flora, as well as in popular science literature on indoor and greenhouse floriculture.

Evolution of branch types

Shoot modifications (metamorphosis)

The shoot is the most variable in appearance organ of the plant. This is due not only to the general multifunctionality of vegetative organs that arose in the process of evolution, but also to the changes that occur in the process of plant ontogenesis, due to adaptation to a variety of conditions. environment, and at cultivated plants- under human influence.

The main type of escape green plant- elevated (air) assimilating shoot, bearing on the axis green leaves middle formation. However, assimilating shoots are not the same. Often, along with the main function of photosynthesis, these shoots also have others: the deposition of reserves and the support function ( for the most part in perennial stems), vegetative reproduction (creeping shoots, lashes).

Modification of underground shoots

Shoots living underground, under the influence of a complex of conditions that are sharply different from ground environment, almost completely lost the functions of photosynthesis and acquired other equally important vital functions, such as organs for transferring an unfavorable period, storing nutrients, vegetative renewal and reproduction of plants. Modified underground shoots include: rhizome, caudex, underground stolon and tuber, bulb, corm.

caudex- a perennial organ of shoot origin of perennial grasses and semi-shrubs with a well-developed taproot that persists throughout the life of the plant. Together with the root, it serves as a place of deposition of reserve substances and bears many renewal buds, some of which may be dormant. There are many caudex plants among the umbrella plants (femur, ferula), legumes (alfalfa, lupins), composites (dandelion, wormwood, rough cornflower).

underground stolon- an annual elongated thin underground shoot with underdeveloped scaly leaves. At the thickened ends of the stolons, plants can accumulate reserve substances, forming tubers or bulbs (potatoes, stolons, adoxas).

stem tuber- a modified shoot with a pronounced storage function of the stem, the presence of scaly leaves that quickly peel off, and buds that form in the axils of the leaves and are called eyes (potato, Jerusalem artichoke).

Bulb- underground (rarely above-ground) highly shortened specialized shoot, in which reserve substances are deposited in scales of leafy nature, and the stem is transformed into the bottom. The bulb is a typical organ of vegetative renewal and reproduction. Bulbs are characteristic of monocotyledonous plants from the Lily family (lily, tulip, onion), Amaryllis (amaryllis, daffodil, hyacinth), etc. As an exception, they are also found in dicotyledonous plants - in some species of sorrel and butterwort.

Corm- a modified underground shortened shoot with a thick stem storing assimilants, adventitious roots growing from the underside of the corm, and preserved dried leaf bases (membraneous scales), which together form a protective cover. Corms have saffron, gladiolus, colchicum.

Modifications of above-ground shoots

An unusual way of life and / or adaptation to the special conditions of the existence of plants lead to various modifications of the shoots. At the same time, shoots can serve not only to store nutrients, reproduce and reproduce plants, but also perform other functions. There are frequent cases when not the entire shoot is modified, but only its leaves, and some of their metamorphoses are outwardly and functionally similar to shoot metamorphoses (thorns, antennae).

thorn- strongly lignified leafless shortened shoot with a sharp tip. Spines of shoot origin perform mainly a protective function. At the wild apple tree, wild pear, laxative buckthorn ( Rhamnus cathartica) shortened shoots turn into spines, having limited growth and ending in a point. In honey locust ( Gleditschia triacanthos) powerful branched spines are formed on the trunks of dormant buds. Many species of hawthorn have spines that form from axillary leaf buds, which topographically corresponds to lateral shoots.

Claudius- a modified lateral shoot with the ability to grow long, with green flat long stems that act as a leaf. As an organ of photosynthesis, the cladodium has a well-developed chlorophyll-bearing tissue located under the epidermis. Plants with cladodias include Mühlenbeckia flatiflora ( Muhlenbekia platyclada), Decembrist cactus ( Zygocactus truncates), southern carmichelia ( Carmichaelia australis), collection ( Colletia cruciata) and prickly pear ( Opuntia).

Phyllocladius- a modified leaf-like flattened lateral shoot with limited growth and performing the functions of a leaf. Phyllocladia develop from lateral buds, so they are always found in the axil of a small membranous or scaly leaf. Performing the function of photosynthesis, the shoots of phylloclades also outwardly acquire a resemblance to a leaf, which manifests itself in limited growth and complete loss of the metameric structure. The phenomenon of phylloclady is characteristic of such plants as the needle, swept away, species of the asparagus genera ( Asparagus), phyllanthus ( Phyllanhtus). Phyllocladia are found not only in angiosperms, but also in some gymnosperms, in particular, in coniferous plant from the family Nogoplodnikovye - phyllocladus.

rosette shoots- abnormal shoots that form on pine trees due to damage done to pine trees by some harmful insects, for example, a nun butterfly, etc .; such shoots are extremely short and have tufts of short and wide needles.

Escape: functions, structure and diversity

When one or another plant is callednie, then in our imagination fussKakaet is just an escape, because, in fromdifference from the root, the escape is visible,the aerial part of the plant. Any dea roar rising from the earth isrun. Even the most powerful. In naturethere are also underground shoots.Are there plants without flowers?stems, without a stem, but always with a cor him and run away!

escape functions. Main escape function -air supply plants. This process is called photosynthesis . For absorption carbon dioxide(it is only 0.03% in the air), and to capture the sun's rays, the plant needs large surface, which is provided by the complex structure of the shoot.

Shoots capable of forming adventitious roots, plants can multiply. Flowers appear on some shoots, fruits and seeds ripen.

Escape structure. A shoot consisting of a stem, leaves and buds is called vegetative . If the shoot also bears flowers, it is calledgenerative .

At the top of the shoot, in the apical bud isshoot growth cone (BUT). The tender cells of its educational tissue are protected by young rudimentary leaves. Due to cell division of the apical educational tissue and their growth, the shoot grows in length. In the internodes isinsert educational fabric (B).

Unlike the apical one, the interstitial educational tissue retains the ability to divide cells only during the growth of the internode. In the adult shoot, these cells turn into cells of permanent tissues, after which the growth of the internode in length stops. In some plants, intercalary growth continues for a long time ( wheat, rye, beans ).

Make captions for the drawing "Escape structure". (Interactive task)

Leaf arrangement. For some shoots, only one leaf can depart from the node (linden, maple, geranium ). This arrangement of leaves is called next . If there are two leaves on a node, then the leaves are located opposite (lilac, elderberry, chickweed ). If a node has three or more leaves, then this whorled leaf arrangement ( raven eye, lily ).

Determine how the leaves are arranged. (Interactive task)

biological game

The arrangement of the leaves on the stem ensures that they receive a stream of sunlight. In low light conditions, indoor plants (balsam, ivy), on the lower branches of trees ( linden, maple) leaf petioles are bent, leaves are displaced, smaller ones fit between large ones.

Leaf mosaic

As a result, all leaves, regardless of the type of leaf arrangement, turn towards the light. Such a phenomenon is calledsheet mosaic .

Escape in a leafless state. In most woody plants, the leaves fall in autumn, and the shoots become leafless. Traces of fallen leaves are clearly visible under each bud. They are calledleaf scars . In place of last year's apical bud remains renal ring .

In winter, trees and shrubs can be easily recognized not only by the shape of the crown, but also by the shape and size of the buds and leaf scars, the color and shape of the stem.

All plants have special characteristics. For example, at alder kidneys sit on special legs. In addition, she has clearly visible earrings and small bumps - fruits. Bud and you covered with a cap. And at buckthorn the kidneys do not have covering scales at all. kidneys mountain ash pubescent. kidneys poplars sticky and resinous. Many plants can be identified by smell. Pleasant, fresh scent poplars, and here at elderberry there is no such smell. You can’t confuse the smell of twigs with anything black currant .

Escape variety. Shoots with well-defined internodes are calledelongated . The internodes do not always elongate (there is no interstitial growth), as a result of which the shoot will consist only of nodes, leaves and buds. Such escapes are called shortened . They are found in both trees and grasses. The short shoots of grasses are called socket (strawberry, dandelion, plantain ).

The shoot emerging from the seedling grows vertically upwards. He - upright (A) (trees and shrubs, as well as many herbaceous plants -rye, bluebell, aster ). But in the future, shoots are formed from its buds, which can grow in different directions. In accordance with the location in space, there are rising (B) (blackhead, carnation grass ), recumbent (bird buckwheat, wood lice ), creeping (D) (hoof, budra, meadow tea ) shoots; creepers: curly (AT) ( bindweed, lemongrass, beans ), clinging (G) (peas, chin, grapes ), climbing (ivy, blackberry).

One type of plant can have different types shoots. For example, at woodlice there are both rising and lying shoots.

Tops of elongated shoots during growth make circular motions. In climbing plants, the scope of circular movements is especially large. Having found support, the shoot wraps around it. Interestingly, some types of plants wrap around the support clockwise, while others wrap it counterclockwise. If such an escape does not find support, then its winding stem will fall to the ground. The tendrils of climbing shoots can be formed from a leaf or part of it ( peas, peas), from side shoots ( grape). Blackberry clings to the support with spikes - outgrowths on the stem, and ivy- short adventitious roots. The botanical names of some plant species reflect the structure of their shoots:creeping clover, creeping ranunculus .

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Shoot - a complex organ of a plant, consisting of a stem, buds and leaves. The structure of the shoot ensures the fulfillment of its main function - air supply. Shoots can be not only vegetative, but also generative. The stem part of the shoot consists of nodes and internodes. The nodes contain leaves and buds.

Either from the axillary or adnexal (adventitious) kidney. Thus, the kidney is a rudimentary shoot. When the seed germinates from the germinal bud, the first shoot of the plant is formed - its main shoot, or first order escape.

From the main shoot are formed side shoots, or second order shoots, and when branching is repeated - of the third order, etc.

Adventitious shoots are formed from adnexal buds.

This is how the system of shoots is formed, represented by the main shoot and side shoots of the second and subsequent orders. The shoot system increases the total area of ​​contact of the plant with the air.

Depending on the function performed, shoots are distinguished as vegetative, vegetative-generative and generative. Vegetative (unmodified) shoots, consisting of a stem, leaves and buds, and vegetative-generative (partially modified), additionally consisting of a flower or inflorescence, perform the functions of air nutrition and provide the synthesis of organic and inorganic substances. In generative (completely modified) shoots, photosynthesis most often does not occur, but sporangia are formed there, the task of which is to ensure plant reproduction (a flower also belongs to such shoots).

The shoot that produces flowers is called flowering shoot, or peduncle(sometimes the term "peduncle" is understood in a narrower sense - as a section of the stem, on which the flowers are located).

Main escape organs

A vegetative unmodified shoot is a single plant organ, consisting of a stem, leaves and buds, formed from a common array of meristems (the cone of growth of the shoot) and having a single conducting system. The stems and leaves, which are the main structural elements of the shoot, are often considered as its constituent organs, that is, organs of the second order. In addition, the obligatory affiliation of the escape is the kidneys. The main external feature that distinguishes the shoot from the root is the presence of leaves.

Monopodial branching

Monopodial branching is the next stage in the evolution of shoot branching. In plants with a monopodial type of shoot structure, the apical bud is preserved throughout the life of the shoot. The monopodial type of branching is often found among gymnosperms, it is also found in many angiosperms (for example, in many species of palms, as well as plants from the Orchid family - gastrochilus, phalaenopsis and others). Some of them have a single vegetative shoot (for example, Phalaenopsis is pleasant).

monopodial plants- the term most often used in the description of plants of tropical and subtropical flora, as well as in popular science literature on indoor and greenhouse floriculture.

Monopodial plants can vary significantly in appearance. Among them there are rosette, with an elongated shoot, bushy.

Sympodial branching

In plants with a sympodial type of shoot structure, the apical bud, having completed development, dies off or gives rise to generative run away. After flowering, this shoot no longer grows, and a new one begins to develop at its base. The structure of the shoot in plants with a sympodial type of branching is more complicated than in plants with; sympodial branching is an evolutionarily more advanced type of branching. The word "simpoidal" is derived from the Greek. sym("together" or "many") and pod("leg").

Sympodial branching is characteristic of many angiosperms: e.g. for limes, willows and many orchids.

In orchids, in addition to the apical ones, some sympodial orchids also form lateral inflorescences, developing from buds located at the base of the shoot (Pafinia comb). The part of the shoot pressed against the substrate is called the rhizome. It is located, as a rule, horizontally and does not have true leaves, only scaly. A reduced, almost indistinguishable rhizome occurs in many Masdevallia, Dendrobiums and Oncidiums; well distinguishable and thickened - in cattleyas and lelias, elongated - in bulbophyllums and cologins, reaching 10 or more centimeters. The vertical part of the shoot is often thickened, forming the so-called tuberidium, or pseudobulb. Pseudobulbs can be of various shapes - from almost spherical to cylindrical, cone-shaped, club-shaped and elongated, resembling reed stalks. Pseudobulbs are storage organs.

sympodial plants- the term most often used in the description of plants of tropical and subtropical flora, as well as in popular science literature on indoor and greenhouse floriculture.

Evolution of branch types

Shoot modifications (metamorphosis)

The shoot is the most variable in appearance organ of the plant. This is due not only to the general multifunctionality of vegetative organs that arose in the process of evolution, but also to the changes that occur in the process of plant ontogenesis, due to adaptation to a variety of environmental conditions, and in cultivated plants - under the influence of man.

The main type of shoot of a green plant is an above-ground (aerial) assimilating shoot, bearing green leaves of the middle formation on the axis. However, assimilating shoots are not the same. Often, along with the main function of photosynthesis, these shoots also have others: the deposition of reserves and the supporting function (mostly in perennial stems), vegetative reproduction (creeping shoots, lashes).

Modification of underground shoots

Shoots living underground, under the influence of a complex of conditions that are sharply different from the terrestrial environment, almost completely lost the functions of photosynthesis and acquired other equally important vital functions, such as organs for enduring an unfavorable period, storing nutrients, vegetative renewal and plant reproduction. Modified underground shoots include: rhizome, caudex, underground stolon and tuber, bulb, corm.

caudex- a perennial organ of shoot origin of perennial grasses and semi-shrubs with a well-developed taproot that persists throughout the life of the plant. Together with the root, it serves as a place of deposition of reserve substances and bears many renewal buds, some of which may be dormant. There are many caudex plants among the umbrella plants (femur, ferula), legumes (alfalfa, lupins), composites (dandelion, wormwood, rough cornflower).

underground stolon- an annual elongated thin underground shoot with underdeveloped scaly leaves. At the thickened ends of the stolons, plants can accumulate reserve substances, forming tubers or bulbs (potatoes, stolons, adoxas).

stem tuber- a modified shoot with a pronounced storage function of the stem, the presence of scaly leaves that quickly peel off, and buds that form in the axils of the leaves and are called eyes (potato, Jerusalem artichoke).

Bulb- underground (rarely above-ground) highly shortened specialized shoot, in which reserve substances are deposited in scales of leafy nature, and the stem is transformed into the bottom. The bulb is a typical organ of vegetative renewal and reproduction. Bulbs are characteristic of monocotyledonous plants from the Lily family (lily, tulip, onion), Amaryllis (amaryllis, daffodil, hyacinth), etc. As an exception, they are also found in dicotyledonous plants - in some species of sorrel and butterwort.

Corm- a modified underground shortened shoot with a thick stem storing assimilants, adventitious roots growing from the underside of the corm, and preserved dried leaf bases (membraneous scales), which together form a protective cover. Corms have saffron, gladiolus, colchicum.

Modifications of above-ground shoots

An unusual way of life and / or adaptation to the special conditions of the existence of plants lead to various modifications of the shoots. At the same time, shoots can serve not only to store nutrients, reproduce and reproduce plants, but also perform other functions. There are frequent cases when not the entire shoot is modified, but only its leaves, and some of their metamorphoses are outwardly and functionally similar to shoot metamorphoses (thorns, antennae).

thorn- strongly lignified leafless shortened shoot with a sharp tip. Spines of shoot origin perform mainly a protective function. At the wild apple tree, wild pear, laxative buckthorn ( Rhamnus cathartica) shortened shoots turn into spines, having limited growth and ending in a point. In honey locust ( Gleditschia triacanthos) powerful branched spines are formed on the trunks of dormant buds. Many species of hawthorn have spines that form from axillary leaf buds, which topographically corresponds to lateral shoots.

Claudius- a modified lateral shoot with the ability to grow long, with green flat long stems that act as a leaf. As an organ of photosynthesis, the cladodium has a well-developed chlorophyll-bearing tissue located under the epidermis. Plants with cladodias include Mühlenbeckia flatiflora ( Muhlenbekia platyclada), Decembrist cactus ( Zygocactus truncates), southern carmichelia ( Carmichaelia australis), collection ( Colletia cruciata) and prickly pear ( Opuntia).

Phyllocladius- a modified leaf-like flattened lateral shoot with limited growth and performing the functions of a leaf. Phyllocladia develop from lateral buds, so they are always found in the axil of a small membranous or scaly leaf. Performing the function of photosynthesis, the shoots of phylloclades also outwardly acquire a resemblance to a leaf, which manifests itself in limited growth and complete loss of the metameric structure. The phenomenon of phylloclady is characteristic of such plants as the needle,

The escape, like the root, is the main organ of the plant. Vegetative shoots typically perform the function of aerial nutrition, but have a number of other functions and are capable of various metamorphoses. spore-bearing shoots (including the flower) are specialized as organs reproductive providing reproduction.

The shoot is formed by the apical meristem as a whole and, therefore, is a single organ of the same rank as the root. However, compared with the root, the shoot has a more complex structure. The vegetative shoot consists of an axial part - stem, which is cylindrical in shape, and leaves- flat lateral organs sitting on the stem. In addition, an obligatory part of the escape are kidneys– rudiments of new shoots, which ensure the growth of the shoot and its branching, i.e. formation of the escape system. The main function of the shoot - photosynthesis - is carried out by leaves; stems are predominantly load-bearing organs that perform mechanical and conductive functions.

The main feature that distinguishes the shoot from the root is its foliage. The part of the stem from which the leaf (leaves) extends is called knot. Stem segments between adjacent nodes internodes. Nodes and internodes are repeated along the axis of the shoot. So the escape has metameric structure, metamer(repeating element) of the shoot are the node with the leaf and the axillary bud and the underlying internode ( rice. 4.16).

Rice. 4.16. Escape structure.

The first shoot of a plant main escape, or escape of the first order. It is formed from an embryonic shoot ending kidney, which forms all subsequent metameres of the main shoot. By position, this kidney is apical; while it persists, this shoot is capable of further growth in length with the formation of new metameres. In addition to the apical, on the shoot are formed lateral kidneys. In seed plants, they are located in the axils of the leaves and are called axillary. From the lateral axillary buds develop lateral shoots, and branching occurs, due to which the total photosynthetic surface of the plant increases. Formed escape system, represented by the main shoot (shoot of the first order) and side shoots (shoots of the second order), and when branching is repeated, by side shoots of the third, fourth and subsequent orders. A shoot of any order has its own apical bud and is capable of growing in length.

Bud- this is a rudimentary, not yet unfolded shoot. Inside the kidney is the meristematic tip of the shoot - its apex(rice. 4.17). The apex is an actively working growth center that ensures the formation of all organs and primary tissues of the shoot. The source of constant self-renewal of the apex is the initial cells of the apical meristem, concentrated at the tip of the apex. The vegetative shoot apex, in contrast to the always smooth root apex, regularly forms protrusions on the surface, which are the beginnings of leaves. Only the very tip of the apex, which is called growth cone escape. Its shape varies greatly in different plants and does not always look like a cone; the apical part of the apex can be low, hemispherical, flat, or even concave.

From vegetative buds develop vegetative shoots consisting of a stem, leaves and buds. Such a kidney consists of a meristematic rudimentary axis ending growth cone, and rudimentary leaves of different ages. Due to uneven growth, the lower leaf primordia are bent inward and cover the upper, younger, leaf primordia and the growth cone. The nodes in the kidney are close together, since the internodes have not yet had time to stretch out. In the axils of leaf rudiments in the kidney, the rudiments of axillary buds of the following order can already be laid ( rice. 4.17). AT vegetative-generative a number of vegetative metameres are laid in the buds, and the growth cone is turned into a rudimentary flower or inflorescence. Generative, or floral the buds contain only the rudiment of an inflorescence or a single flower, in the latter case the bud is called bud.

Rice. 4.17. The apical bud of the Elodea shoot: A - longitudinal section; B - growth cone ( appearance and longitudinal section); C – cells of the apical meristem; D - parenchymal cell of the formed leaf; 1 - growth cone; 2 - leaf rudiment; 3 - the rudiment of the axillary kidney.

The outer leaves of the bud often change into kidney scales, which perform a protective function and protect the meristematic parts of the kidney from drying out and sudden changes in temperature. Such kidneys are called closed(wintering buds of trees and shrubs and some perennial herbs). open kidneys do not have kidney scales.

In addition to the usual, exogenous in inception, axillary buds, plants often form adnexal, or adventive kidneys. They arise not in the meristematic tip of the shoot, but on the adult, already differentiated part of the organ, endogenously, from internal tissues. Adnexal buds can form on stems (then they are usually located in internodes), leaves and roots. Adnexal buds are of great biological importance: they provide active vegetative renewal and reproduction of those perennials who have them. In particular, with the help of adnexal kidneys, they renew and multiply root offspring plants (raspberry, aspen, thistle, dandelion). Root offspring- these are shoots that have developed from adventitious buds on the roots. Adnexal buds on the leaves are formed relatively rarely. If such buds immediately give small shoots with adventitious roots that fall off the mother leaf and grow into new individuals, they are called brood(bryophyllum).

In the seasonal climate of the temperate zone, the deployment of shoots from the buds in most plants is periodic. Trees and shrubs, as well as many perennials herbaceous plants buds unfold into shoots once a year - in spring or early summer, after which new wintering buds form with the beginnings of next year's shoots. Shoots that grow from buds in one growing season are called annual shoots, or annual increments. In trees, they are well distinguished due to the formation renal rings- scars that remain on the stem after the fall of the kidney scales. In the summer of our deciduous trees, the annual shoots of only the current year are covered with leaves; there are no leaves on the annual shoots of previous years. In evergreen trees, leaves can be preserved on the corresponding annual increments of 3-5 past years. In a seasonally unseasoned climate, several shoots may form in one year, separated by small dormant periods. Such shoots formed in one growth cycle are called elementary shoots.

Buds that fall into a dormant state for a while, and then give new elementary and annual shoots, are called wintering or resting. According to their function, they can be called kidney regular renewal. Such buds are an obligatory feature of any perennial plant, woody or herbaceous, they ensure the perennial existence of an individual. By origin, renewal kidneys can be both exogenous (apical or axillary) and endogenous (adnexal).

If the lateral buds do not have a dormant period and develop simultaneously with the growth of the maternal shoot, they are called kidney enrichment. Deploying ones enrichment shoots greatly increase (enrich) the total photosynthetic surface of the plant, as well as total number formed inflorescences and, consequently, seed productivity. Enrichment shoots are typical for most annual grasses and for a number of perennial herbaceous plants with elongated flowering shoots.

A special category is dormant buds, very characteristic of deciduous trees, shrubs, shrubs and a number of perennial grasses. By origin, they, like the buds of regular renewal, can be axillary and adnexal, but, unlike them, do not turn into shoots for many years. The stimulus for the awakening of dormant buds is usually either damage to the main trunk or branch (stump growth after cutting down a number of trees), or natural aging of the maternal shoot system associated with the attenuation of the vital activity of normal renewal buds (change of stems in shrubs). In some plants, leafless flowering shoots form from dormant buds on the trunk. This phenomenon is called caulifloria and is characteristic of many rainforest trees, such as the chocolate tree. In honey locust, bunches of large branched spines grow from sleeping buds on the trunk - modified shoots ( rice. 4.18).

Rice. 4.18. Shoots from dormant buds: 1 - caulifloria near the chocolate tree; 2 - spines in honey locust from branched dormant buds.

Direction of shoot growth. Shoots growing vertically, perpendicular to the surface of the earth, are called orthotropic. Horizontally growing shoots are called plagiotropic. The direction of growth may change during shoot development.

Depending on the position in space, morphological types of shoots are distinguished ( rice. 4.19). The main shoot in most cases retains orthotropic growth and remains upright. Lateral shoots can grow in different directions, often forming a different angle with the parent shoot. In the process of growth, the shoot can change direction from plagiotropic to orthotropic, then it is called rising, or ascending. Shoots with plagiotropic growth that persists throughout life are called creeping. If they form adventitious roots at the nodes, they are called creeping.

Orthotropic growth is connected in a certain way with the degree of development of mechanical tissues. In the absence of well-developed mechanical tissues in elongated shoots, orthotropic growth is impossible. But often plants that do not have a sufficiently developed internal skeleton still grow upward. This is achieved in various ways. Weak shoots of such plants - creeper twist around some kind of solid support ( curly shoots), climb with the help of various kinds of spines, hooks, roots - trailers ( climbing shoots), cling with the help of antennae of various origins ( clinging shoots).

Rice. 4.19. Types of shoots by position in space: A - upright; B - clinging; B - curly; G - creeping; D - creeping.

Leaf arrangement. leaf arrangement, or phyllotaxis- the order of placement of leaves on the axis of the shoot. There are several main types of leaf arrangement ( rice. 4.20).

Spiral, or another leaf arrangement is observed when there is one leaf at each node, and the bases of successive leaves can be connected by a conditional spiral line. double row leaf arrangement can be considered as special case spiral. At the same time, at each node there is one sheet, covering the entire or almost the entire circumference of the axis with a wide base. Whorled leaf arrangement occurs when several leaves are laid on one node. Opposite leaf arrangement - a special case of whorled, when two leaves are formed on one node, exactly opposite each other; most often such a leaf arrangement occurs cross opposite, i.e. neighboring pairs of leaves are in mutually perpendicular planes ( rice. 4.20).

Rice. 4.20. Types of leaf arrangement: 1 - spiral in oak; 2 - scheme of spiral leaf arrangement; 3 - two-row in gasteria ( a- side view of the plant b– top view, scheme); 4 - whorled in oleander; 5 - opposite in lilac.

The order of initiation of leaf rudiments on the shoot apex is a hereditary trait of each species, sometimes characteristic of a genus and even an entire family of plants. The leaf arrangement of the adult shoot is determined primarily by genetic factors. However, in the process of deployment of a shoot from a bud and its further growth, the arrangement of leaves can be influenced by external factors mainly lighting conditions and gravity. Therefore, the final picture of the leaf arrangement can differ greatly from the initial one and usually acquires a pronounced adaptive character. The leaves are arranged so that their plates are in the most favorable lighting conditions in each case. This is most pronounced in the form sheet mosaic observed on plagiotropic and rosette shoots of plants. In this case, the plates of all leaves are arranged horizontally, the leaves do not obscure each other, but form a single plane where there are no gaps; smaller leaves fill the gaps between the larger ones.

Shoot branching types. Branching is the formation of a system of axes. It provides an increase in the total area of ​​​​contact of the plant body with air, water or soil. Branching arose in the process of evolution even before the appearance of organs. In the simplest case, the top of the main axis forks and gives rise to two axes of the next order. This is apical, or dichotomous branching. Many multicellular algae have apical branching, as well as some primitive plants, such as club mosses ( rice. 4.21).

Other groups of plants are characterized by a more specialized side branch type. In this case, the lateral branches are laid below the top of the main axis, without affecting its ability to further increase. With this method, the potential for branching and formation of organ systems is much more extensive and biologically beneficial.

Rice. 4.21. Shoot branching types: A - dichotomous (club moss); B - monopodial (juniper); B - sympodial type of monochasia (bird cherry); D - sympodial according to the type of dichasia (maple).

There are two types of lateral branching: monopodial and sympodial(rice. 4.21). With a monopodial branching system, each axis is a monopodium, i.e. the result of the work of one apical meristem. Monopodial branching is characteristic of most gymnosperms and many herbaceous angiosperms. Most angiosperms, however, branch in a sympodial pattern. With sympodial branching, the apical bud of the shoot dies off at a certain stage or stops active growth, but an increased development of one or more lateral buds begins. Shoots are formed from them, replacing the shoot that has stopped growing. The resulting axis is a sympodium - a composite axis consisting of axes of several successive orders. The ability of plants to sympodial branching is of great biological importance. In case of damage to the apical bud, the growth of the axis will continue with lateral shoots.

Depending on the number of replacement axes, sympodial branching is distinguished by type monochasia, dichasia and pleiochasia. Branching according to the type of dichasia, or false dichotomous branching is typical for shoots with opposite leaf arrangement (lilac, viburnum).

In some groups of plants, the growth of the main skeletal axes occurs due to one or a few apical buds, lateral skeletal branches are not formed at all or are formed in a very small number. Tree-like plants of this type are found mainly in tropical areas (palm trees, dracaena, yucca, agave, cycads). The crown of these plants is formed not by branches, but by large leaves brought together in a rosette at the top of the trunk. The ability to rapidly grow and capture space, as well as to recover from damage in such plants is often absent or weakly expressed. Among the trees temperate climate such unbranched forms are almost never found.

The other extreme is plants that branch too profusely. They are represented by the life form cushion plants (rice. 4.22). The growth in the length of the shoots of these plants is extremely limited, but on the other hand, many lateral branches are formed annually, diverging in all directions. The surface of the shoot system of the plant looks as if trimmed; some pillows are so dense that they look like stones.

Rice. 4.22. Plants - pillows: 1, 2 - schemes of the structure of pillow plants; 3 - Azorella from Kerguelen Island.

Representatives of a life form branch very strongly Tumbleweed characteristic of steppe plants. A spherically branched, very loose system of shoots is a huge inflorescence, which, after fruit ripening, breaks off at the base of the stem and rolls over the steppe with the wind, scattering the seeds.

Specialization and metamorphoses of shoots. Many plants within the shoot system have a certain specialization. Orthotropic and plagiotropic, elongated and shortened shoots perform different functions.

elongated called shoots with normally developed internodes. In woody plants, they are called growth and are located along the periphery of the crown, determining its shape. Their main function is to capture space, increase the volume of photosynthetic organs. shortened shoots have close nodes and very short internodes ( rice. 4.23). They form inside the crown and absorb scattered light penetrating there. Often shortened shoots of trees are flowering and perform the function of reproduction.

Rice. 4.23. Shortened (A) and elongated (B) sycamore shoots: 1 - internode; 2 - annual increments.

Herbaceous plants usually have shortened rosette shoots perform the function of perennial skeletal and photosynthetic, and elongated ones are formed in the axils of rosette leaves and are flower-bearing (plantain, cuff, violets). If axillary peduncles are leafless, they are called arrows. The fact that flowering shoots are short in woody plants and elongated in herbaceous plants is biologically well explained. For successful pollination, grass inflorescences must be raised above the herbage, and in trees, even shortened shoots in the crown are in favorable conditions for pollination.

An example of the specialization of shoots is the perennial axial organs of woody plants - trunks and branches crowns. In deciduous trees, annual shoots lose their assimilation function after the first growing season, in evergreen trees - after a few years. Some of the shoots die off completely after the loss of leaves, but the majority remain as skeletal axes, performing supporting, conducting, and storage functions for decades. The leafless skeletal axes are known as boughs and trunks(by the trees) stems(for shrubs).

In the course of adaptation to specific environmental conditions or in connection with a sharp change in functions, shoots can change (metamorphize). Shoots developing underground are especially often metamorphosed. Such shoots lose the function of photosynthesis; they are common in perennial plants, where they act as organs for experiencing an unfavorable period of the year, stock and renewal.

The most common underground shoot metamorphosis is rhizome (rice. 4.24). It is customary to call a rhizome a long-lived underground shoot that performs the functions of deposition of reserve nutrients, renewal, and sometimes vegetative reproduction. The rhizome is formed in perennial plants, which, as a rule, do not have a main root in the adult state. According to its position in space, it can be horizontal, oblique or vertical. The rhizome usually does not bear green leaves, but, being a shoot, retains a metameric structure. The nodes are distinguished either by leaf scars and the remains of dry leaves, or by living scaly leaves, and axillary buds are also located in the nodes. According to these features, the rhizome is easy to distinguish from the root. As a rule, adventitious roots are formed on the rhizome; lateral branches of the rhizome and above-ground shoots grow from the buds.

The rhizome is formed either initially as an underground organ (kupena, raven eye, lily of the valley, blueberry), or first as an above-ground assimilating shoot, which then sinks into the soil with the help of retracting roots (strawberry, lungwort, cuff). Rhizomes can grow and branch monopodially (cuff, crow's eye) or sympodially (kupena, lungwort). Depending on the length of the internodes and the intensity of growth, there are long and short rhizomes and, accordingly, long-rhizome and short-rhizome plants.

When branching rhizomes, it is formed curtain elevated shoots connected by sections of the rhizome system. If the connecting parts are destroyed, the shoots are isolated, and vegetative reproduction occurs. The totality of new individuals formed vegetatively is called clone. Rhizomes are characteristic mainly of herbaceous perennials, but are also found in shrubs (euonymus) and shrubs (lingonberries, blueberries).

close to roots underground stolons- short-lived thin underground shoots bearing underdeveloped scaly leaves. Stolons serve for vegetative reproduction, settlement and territory capture. Spare nutrients are not deposited in them.

In some plants (potato, earth pear), by the end of summer, stolons form from the apical buds of stolons. tubers (Fig. 4.24). The tuber has a spherical or oval shape, the stem is strongly thickened, reserve nutrients are deposited in it, the leaves are reduced, and buds form in their axils. The stolons die off and collapse, the tubers overwinter, and the next year they give rise to new above-ground shoots.

Tubers do not always develop on stolons. In some perennial plants, the base of the main shoot grows tuberous and thickens (cyclamen, kohlrabi cabbage) ( rice. 4.24). The functions of the tuber are a supply of nutrients, experiencing an unfavorable period of the year, vegetative renewal and reproduction.

In perennial grasses and dwarf shrubs with a well-developed tap root that persists throughout life, a kind of organ of shoot origin is formed, called caudex. Together with the root, it serves as a place for the deposition of reserve substances and carries many renewal buds, some of which may be dormant. The caudex is usually subterranean and is formed from short shoot bases that sink into the soil. Caudex differs from short rhizomes in the way it dies off. Rhizomes, growing at the top, gradually die off and collapse at the older end; the main root is not preserved. The caudex grows in width, from the lower end it gradually turns into a long-lived thickening root. The death and destruction of the caudex and the root goes from the center to the periphery. A cavity is formed in the center, and then it can be divided longitudinally into separate sections - particles. The process of dividing an individual of a taproot plant with a caudex into parts is called particulation. There are many caudex plants among legumes (lupins, alfalfa), umbrella plants (femur, ferula), and Compositae (dandelion, wormwood).

Bulb- this is usually an underground shoot with a very short flattened stem - bottom and scaly fleshy succulent leaves that store water and soluble nutrients, mainly sugars. Aerial shoots grow from the apical and axillary buds of the bulbs, adventitious roots form on the bottom ( rice. 4.24). Thus, the bulb is a typical organ of vegetative renewal and reproduction. Bulbs are most characteristic of plants from the families of lilies (lilies, tulips), onions (onions) and amaryllis (daffodils, hyacinths).

The structure of the bulb is very diverse. In some cases, bulbs storing scales are only modified leaves that do not have green plates (lily saranka); in others, these are underground sheaths of green assimilating leaves, which thicken and remain in the bulb after the plates die (onion). Bulb axis growth can be monopodial (snowdrop) or sympodial (hyacinth). The outer scales of the bulb consume the supply of nutrients, dry out and play a protective role. The number of onion scales varies from one (garlic) to several hundred (lilies).

As an organ of renewal and reserve, the bulb is adapted mainly to climates of the Mediterranean type - with fairly mild, wet winters and very hot, dry summers. It serves not so much for a safe overwintering, but for experiencing a harsh summer drought. The storage of water in the tissues of onion scales occurs due to the formation of mucus, which can retain a large amount of water.

Corm outwardly resembles an onion, but its scaly leaves are not storage; they are dry and membranous, and reserve substances are deposited in the thickened stem part (saffron, gladiolus).

Rice. 4.24. Underground escape metamorphoses: 1, 2, 3, 4 - sequence of development and structure of the potato tuber; 5 - cyclamen tuber; 6 - kohlrabi tuber; 7 - bulbs of a tiger lily; 8 - onion bulb; 9 - lily bulb; 10 - section of a long rhizome of couch grass.

Not only underground, but also above-ground shoots of plants can be modified ( rice. 4.25). Quite common elevated stolons. These are plagiotropic short-lived shoots, the function of which is vegetative reproduction, resettlement and territory capture. If stolons carry green leaves and participate in the process of photosynthesis, they are called lashes(bone, tenacious creeping). In strawberries, stolons are devoid of developed green leaves, their stems are thin and fragile, with very long internodes. Such more highly specialized for function vegetative propagation stolons are called mustache.

Juicy, fleshy, adapted for the accumulation of water can be not only bulbs, but also above-ground shoots, usually in plants living in conditions of lack of moisture. Water storage organs can be leaves or stems, sometimes even buds. Such succulent plants are called succulents. Leaf succulents store water in leaf tissues (aloe, agave, jughead, rhodiola, or golden root). Stem succulents are characteristic of the American cactus family and African euphorbiaceae. The succulent stem performs a water-reserving and assimilating function; leaves are reduced or turned into spines ( rice. 4.25, 1). In most cacti, the stems are columnar or spherical, leaves are not formed on them at all, but the nodes are clearly visible by the location of the axillary shoots - areola having the appearance of warts or elongated outgrowths with spines or tufts of hairs. The transformation of leaves into spines reduces the evaporative surface of the plant and protects it from being eaten by animals. An example of the metamorphosis of a kidney into a succulent organ is head of cabbage serves as a cultivated cabbage.

Rice. 4.25. Elevated shoot metamorphoses: 1 - stem succulent (cactus); 2 - tendrils of grapes; 3 - leafless photosynthetic shoot of gorse; 4 - phyllocladium of butcher's broom; 5 - thorn of honey locust.

spines cacti are leafy. Leaf spines are often found in non-succulent plants (barberry) ( rice. 4.26, 1). In many plants, spines are not of leaf, but of stem origin. At wild apple tree, wild pear, laxative joster, shortened shoots are metamorphosed into spines, having limited growth and ending in a point. They acquire the appearance of a hard lignified thorn after the leaves fall. At the hawthorn ( rice. 4.26, 3) the spines that form in the axils of the leaves are completely leafless from the very beginning. In honey locust ( rice. 4.25.5) powerful branched spines are formed on trunks from dormant buds. The formation of spines of any origin, as a rule, is the result of a lack of moisture. When many thorny plants are grown in an artificial humid atmosphere, they lose their spines and instead grow normal leaves (camel thorn) or leafy shoots (English gorse).

Rice. 4.26. Spines of various origins: 1 - barberry leaf spines; 2 - spines of white acacia, modification of stipules; 3 - spines of hawthorn shoot origin; 4 - thorns - rosehip emergents.

The shoots of a number of plants bear spikes. Thorns differ from spines in smaller sizes, these are outgrowths - emergents - of the integumentary tissue and tissues of the stem bark (rose hips, gooseberries) ( rice. 4.26, 4).

Adaptation to a lack of moisture is very often expressed in the early loss, metamorphosis or reduction of leaves that lose the main function of photosynthesis. This is compensated by the fact that the stem takes on the role of the assimilating organ. Sometimes such an assimilating stem of a leafless shoot remains externally unchanged (Spanish gorse, camel thorn) ( rice. 4.25, 3). The next step in this change of functions is the formation of such organs as phyllocladia and cladodia. These are flattened leaf-like stems or whole shoots. On the shoots of the needle ( rice. 4.25, 4), in the axils of scaly leaves, flat leaf-shaped phylloclades develop, which, like a leaf, have limited growth. Scale-like leaves and inflorescences form on phylloclades, which never happens on normal leaves, which means that the phyllocladium corresponds to the whole axillary escape. Small, needle-like phylloclades are formed in asparagus in the axils of the scaly leaves of the main skeletal shoot. Cladodia are flattened stems that, unlike phyllocladia, retain the ability for long-term growth.

Some plants are characterized by the modification of leaves or their parts, and sometimes entire shoots in antennae, which twist around the support, helping the thin and weak stem to keep vertical position. In many legumes, the upper part of the pinnate leaf (peas, peas, rank) turns into antennae. In other cases, stipules (sarsaparilla) turn into antennae. Very characteristic tendrils of leafy origin are formed in gourds, and all the transitions from normal to fully metamorphosed leaves can be seen. Antennae of shoot origin can be observed in grapes ( rice. 4.25, 2), passionflower and a number of other plants.

The shoot of a plant is one of the main vegetative organs. It consists of three parts: root, stem and leaf. All currently existing higher plants they are homologous to each other and perform different functions.

Shoot phylogeny

In the context historical development organisms, called phylogenesis, escape is regarded as an adaptation to a terrestrial lifestyle. It arose as a result of the transformation of rhinophytes of telomes (leafless cylindrical organs) in primitive vascular plants. The emergence of the shoot is the largest aromorphosis in the history of development flora. This progressive change led to an increase in photosynthetic surface area, associated transpiration, and, as a result, promoted the development of true roots.

Ontogenesis

At individual development organism (ontogenesis), the shoot of a plant is formed from the buds of the embryo, or adnexal or axillary buds. They are, in fact, the beginnings. When the seed germinates from the germinal bud, the first shoot of the plant develops, also called the main or first order. Lateral branches develop from it.

Types of shoots depending on the function performed

• Vegetative shoots are unmodified. They consist of a stem, buds and leaves. The main function is air supply and ensuring the process of synthesis of inorganic and organic substances.
• Generative shoots are modified. In them, the process of photosynthesis is not carried out, as a rule. However, sporangia are formed on them, the main task of which is to ensure the process of plant reproduction.
• Vegetative-generative, that is, a partially modified shoot. It has leaves, stem, buds and flowers or inflorescences at the same time. Accordingly, it combines the two functions mentioned above at once.

Often the shoot on which the formation of flowers occurs is called the flower-bearing or abbreviated "peduncle".

Escape: building

Without exception, all shoots carry leaves that are not always visible to the eye (for example, scaly on rhizomes). Woody plants are characterized by their absence on perennial plots. Old leaves, after the formation of a special separating tissue, fall off at the end of each season - this is a feature of deciduous species. In the spring, the growth process begins anew.

The place where a leaf is attached to a stem is called a node. In many plants, it is thicker than in other areas. The part of the shoot located between the nodes is the internode. Their alternation expresses the metameric structure of the branches. The repeating structural unit in this case is a node with a leaf and an internode - a phytomer.

Often, the length of the internode can differ significantly on the shoots of the same plant. Quite often one can meet in nature fluctuations in one direction or another. So, strongly shortened internodes lead to the emergence of rosette shoots and bulbs, and excessively elongated, to the development of stolons or peduncles.

Growth Features

Summarizing the above, we can say that the stem with leaves and buds, formed from the meristem, is an unmodified vegetative shoot. In temperate latitudes, their growth and development is periodic. As a rule, in most shrubs, trees and perennial grasses, it occurs once a year (in spring or summer). Such shoots that grow in one year are called annual shoots. In perennial plants, an apical bud is formed at their end; in fact, it is the beginning of a future shoot, which is a continuation of the main axis.

In cases where the growing season consists of several stages of growth, which are separated from each other by a weakly pronounced dormant period, the growing shoots are called elementary. This is especially true for oak. The tree forms shoots in spring and mid-summer. In the tropics there is no clear division into seasons. As a result, many citrus fruits tea bush etc. can form from 3 to 7 elementary shoots per year.

branching shoots

The process of formation of lateral branches by a shoot, their relative position on a stem, rhizome or perennial branch is called branching. In this way, the plant increases the above-ground mass and surface area, and hence the power of photosynthesis. The order in which the main shoot and buds are located serves as a criterion for classifying branching. It can be dichotomous, monopodial and sympodial. These species are characteristic of higher plants; in lower plants, branching leads to the formation of a thallus (thallus).

The main shoot or axis of the first order develops from the apical bud, its lateral stems are the axes of the second order. They keep branching out. In this case, axes of the third, fourth, etc. order are formed. Let's dwell on each type of branching in more detail.

Dichotomous branching

This type of branching is the most primitive. It is characteristic of algae, such as fucus, club mosses, some gymnosperms, mosses and ferns. With dichotomous branching, the growth cone is divided in two, as a result, two side branches are formed. They, in turn, grow in a similar way further. At the same time, the shoot, the structure of which was discussed above, forms a bizarre "tree" (pictured).

Dichotomous branching can be isotomous, when the newly formed branches are of the same length, or anisotomous, when they are unequal.

Monopodial branching

More progressive in evolutionary terms is monopodial branching. Plants with this type of shoot structure retain the apical bud throughout their lives. The increase in height occurs due to the main axis. Lateral branching shoots can depart from it. However, they are never above the main. Monopodial branching can most often be found in representatives of the group of gymnosperms, some angiosperms (palms, orchids, etc.) plants. A classic example is common in room culture phalaenopsis is pleasant, having only one vegetative shoot.

Sympodial branching

Sympodial branching is the most advanced and complex type compared to the previous ones. It is characteristic of angiosperms. Escape the building that gets under given type, differs in that its kidney (apical), ending its development, dies off or stops its growth. New stems begin to develop at its base. Moreover, such side shoots outgrow the main one, take on its direction and appearance. Sympodial branching has, in particular, birch, linden, hazel, and most flowering plants.

The most variable in appearance organ of plants is the shoot. Its structure remains the same, but it can take on a variety of forms. This property is mainly associated with the multifunctionality of all vegetative organs that arose in the course of evolution, and the changes that occur in ontogeny, which are due to the adaptation of the plant to various external conditions.

Shoot metamorphoses have a very wide range: from small deviations from the typical structure to completely changed forms. Both underground and above-ground parts can be modified.

Metamorphoses of above-ground shoots

The modifications that occur with the shoot, listed below, are the consequences of the adaptation of the plant to special conditions of existence or an unusual way of life. These formations can serve not only for reproduction and reproduction, the accumulation of nutrients, but also perform other functions.

• Whiskers and elevated stolons. These modifications of the stem are intended for vegetative reproduction of the plant, i.e., the settlement of its daughter individuals. Such shoots can carry leaves and carry out photosynthesis in parallel. Typical example- whiskers of wild strawberries, stolons of indoor chlorophytum.
• Antennae.

• As a rule, they have climbing plants. The antennae are a flagellate shoot (branched or solitary), devoid of leaves. They are highly specialized formations that perform a supporting function in species that cannot independently maintain a vertical position. Antennae have, for example, such climbing plants as peas, morning glory, as well as representatives of the Pumpkin family (cucumber, watermelon, pumpkin, melon).
• Thorns are strongly shortened lignified leafless shoots with a sharp top. They are a protective adaptation of plants.
• Rosette escapes. They have very short internodes, as a result of which the leaves are arranged in a rosette. For example, like plantain, dandelion, daisy.
• Phyllocadium is a lateral shoot with limited growth, flattened and performing the function of a leaf. Characteristic for representatives of the genus asparagus, phyllanthus.
• Claudius. In order to understand what it is, just look at the parts of the stem room Decembrist, prickly pear cactus. This is modified escape characterized by long-term growth. It has flattened stems that act as leaves, while the latter are practically reduced.

Metamorphoses of underground shoots

Shoots located underground are very different from those above ground. They almost completely lost the function of photosynthesis, but acquired others, no less important. For example, the supply of nutrients, reproduction, resumption of vegetative growth. Modifications of the underground shoot are: caudex, rhizome, stolon, bulb and corm.

• Caudex - a modified section of the stem, located between the cotyledon leaves and the tap root. It has the appearance of a thickening, persists throughout the life of the plant and serves as a storage place for reserve nutrients, and also carries numerous renewal buds, including dormant ones. For example, lupins, adenium, alfalfa.
• Rhizome - a modified underground shoot, characteristic of perennial grasses, shrubs and semi-shrubs. Outwardly, it is very similar to the root. The main difference lies in the location and growth in a horizontal plane, the presence of scale-like leaves and the absence of a root cap.
• An underground stolon is an annual thin elongated shoot located underground, at the end of which tubers and bulbs (potatoes, adoxas) can develop.
• The bulb is a specialized, greatly shortened shoot, most often underground. It is a typical organ of vegetative renewal and reproduction.
• The corm is also a shortened modified underground shoot. However, in addition to the function of vegetative reproduction, it stores assimilates in itself. For example, gladioli, dahlias, cyclamen, callas, etc.