All plant organs are divided into vegetative and generative (Fig. 1):
Rice. 1. Plant organs
Vegetative organs- organs that carry out vegetative processes: growth, nutrition, respiration, plant metabolism.
plant generative organs organs involved in reproduction.
The escape- the aerial part of the plant.
Root- the underground part of the plant.
The shoot consists of a stem bearing buds, leaves and generative organs.
Since the buds and flowers are essentially shortened shoots, the entire aerial part of the plant is considered as a shoot system.
shoot structure
The shoot has unlimited apical (apical) growth.
At the end of the run is apical kidney. It ensures the growth of the shoot in length. The basis of the apical kidney is the educational tissue - the apical, or apical meristem. It formsgrowth cone. The cells of this tissue, dividing, give rise to all the primary tissues of the young shoot: integumentary, conductive, mechanical, parenchymal. The rudimentary leaves laid in this place initially bend upward and cover the growth cone, protecting it from adverse influences. Subsequently, with the growth of the shoot, the growth cone moves forward, while the leaves remain and turn into ordinary leaves of the plant, directed, as a rule, to the sides (Fig. 2).
Rice. 2. Increasing cone
Lateral kidneys located in nodes stem (Fig. 3). Leaves develop from them.
internode- distance between nodes.
Rice. 3. The structure of the escape
Initially, in the area under the apical bud, the internodes are small, but as the stem grows, they stretch, reaching a value characteristic of this plant species under these conditions. The length of the internodes depends, for example, on the illumination: in good light they are shorter, and in shading they are longer.
Leaf axil- the angle between the petiole of the leaf and the stem.
The kidney is a shortened rudimentary shoot. It consists of a short section of the stem with an apical meristem at the end and scales, into which the first leaves of this shoot have turned. They close the kidney from the outside and protect it from adverse effects. The number of such buds is equal to the number of leaves. In the future, side shoots may develop from them. Since the leaf lives for a limited time, after it dies, it remains on the stemleaf scar, above which there is an axillary bud or lateral shoot (Fig. 4).
axillary kidney- a bud in the axil on the stem.
In the axils of the leaves, one bud is usually formed. However, in some plants, such as raspberries, honeysuckle, walnuts, there are several buds located one above the other in the leaf axil (Fig. 5).
Rice. 4. Kidneys Fig. 5. Axillary honeysuckle buds
Adnexal kidneys- buds arising from internal tissues on stems, leaves, roots (Fig. 6). In structure, these kidneys are no different from the usual apical and axillary. They provide intensive growth and vegetative reproduction (reproduction by root offspring).
dormant buds- buds that develop only under certain conditions into a leafy or flower-bearing shoot (Fig. 7, 8). When the main trunk slows down its growth or is cut down, dormant buds begin to grow, and leafy shoots grow from them. And even without external damage, old trees can “rejuvenate” due to them.
Rice. 6. Adnexal kidneys 7. Dormant buds 8. Sleeping kidney (diagram)
According to the functions performed, the kidneys are divided into vegetative (rudimentary vegetative shoot) and generative (rudimentary generative shoot) (Fig. 9).
Rice. 9. Internal structure of the kidneys
leaf arrangement
The number of leaves per node varies and is usually characteristic of each plant species. It determines the type of leaf arrangement.
There are three types of leaf arrangement (Fig. 10):
Rice. 10. Leaf arrangement
The next, or spiral, leaf arrangement:the leaves at the nodes are located one at a time, but depart alternately in different directions, and if you connect the attachment points of such leaves with a line, you get a spiral (Fig. 11).
Rice. 11. Spiral leaf arrangement
Examples of plants with a spiral leaf arrangement: apple, oak, birch, wild rose. This type of arrangement is the most common.
Opposite leaf arrangement: two leaves extend from one node, directed in opposite directions. The leaves at the next node are most often rotated by 90°, although there are plants in which all pairs of leaves are in the same plane. Examples of plants with opposite leaf arrangement: lilac, ash, mint, phlox, willow-herb, euonymus.
Whorled leaf arrangement: one node leaves three or more leaves. In some plants, the number of leaves in the whorl is constant, in others it may vary.
Examples: horsetail, raven eye, elodea, bedstraw, oleander.
shoot branching
branching- this is the formation of lateral shoots from axillary buds. A highly branched system of shoots is obtained when side shoots grow on one (“mother”) shoot, and on them, the next side ones, and so on. In this way, as much air supply medium as possible is captured. The branched crown of the tree creates a huge leaf surface.
Depending on the location and origin of the side shoots, several types of branching are distinguished (Fig. 12).
Rice. 12. Types of shoot branching
Dichotomous branching- the most ancient type of branching, which has been preserved in primitive forms. Branching occurs due to the doubling of the point of growth. In this case, two shoots are formed, which in turn can branch in the same way.
Examples: algae, lichens, bryophytes, outgrowths of some horsetails and ferns.
Branching occurs in seed plants due to the development of shoots from axillary buds.
Monopodial branching: the main shoot (first-order shoot) continues to grow, forming the main trunk, and second-order shoots depart from it, from those, in turn, third-order shoots, etc. Such shoots are ordered, and the crowns are slender. But if the apical bud is damaged, this type of branching is not restored, and the tree loses its typical appearance ( habit).
Example: coniferous trees - pine, spruce, cypress, etc.
Sympodial branching- the most recent type of branching in time of occurrence. The shoot of the first order deviates from the main axis and turns into a side branch or dies. It is replaced by a lateral shoot developing from the axillary bud. In turn, it also deviates to the side, and the place of the main axis of the plant is occupied by a third-order shoot. With this type of branching, any bud can continue the growth of the shoot if it is damaged. With prolonged growth and a significant increase in the thickness of the shoot, the boundaries between shoots of different orders become invisible, and we see a single tree trunk.
Example: most deciduous trees - apple, aspen, linden, etc.
In the case of opposite arrangement of leaves in the node, there are two axillary buds. With sympodial branching and with the simultaneous and identical development of both side shoots, a branching is formed, called false dichotomous.
Example: lilac, maple, mock orange.
tillering- this is branching, in which large side shoots grow from the lowest buds located near the surface of the earth or even underground. As a result of tillering, a bush is formed.
Very dense perennial bushes are called turfs.
escape form
Escapes are:
erect- shoots with a stem growing vertically upwards (poplar, oats, sunflower);
rising- shoots, first growing in a horizontal and then vertical direction (cinquefoil paniculata, marsh cinquefoil);
creeping- growing more or less horizontally (cranberries, goose cinquefoil);
creeping- shoots similar to creeping ones, but unlike them, rooting with the help of adventitious roots formed at the nodes (strawberries, creeping tenacity);
curly- shoots capable of twining around other plants or any supports (field bindweed, hops);
climbing- shoots with devices (antennae, suckers, hooks, etc.) for holding on supports or on other plants (peas, grapes, ivy).
The shoot of a plant is one of the main vegetative organs. It consists of three parts: root, stem and leaf. In all currently existing higher plants, they are homologous to each other and perform different functions.
Shoot phylogeny
In the context of the historical development of organisms, called phylogeny, 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 a shoot is the largest aromorphosis in the history of the development of the plant world. This progressive change led to an increase in photosynthetic surface area, associated transpiration, and, as a result, promoted the development of true roots.
Ontogenesis
With the individual development of the organism (ontogenesis), the shoot of the 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). A woody plant is characterized by their absence in 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. In this regard, many citrus fruits, a 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 the pleasing phalaenopsis, common in room culture, which has 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. The escape structure, which falls under this type, is distinguished by the fact that its bud (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. A typical example is the whiskers of wild strawberries, stolons of indoor chlorophytum.
- Antennae.
- As a rule, climbing plants have them. 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, climbing plants such 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 parts of the stem of the indoor Decembrist, prickly pear cactus. This is a modified shoot, characterized by long 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.
Shoot - one of the main organs of higher plants, consisting of a stem, leaves and buds. On the stem of the shoot are nodes and internodes. The node is the place where the leaves and buds are connected to the stem. The angle between the stem and the leaf is called the leaf axil. The kidney that is located there is called axillary. In addition to the axillary buds, there are also apical ones.
The stem is the axial part of the shoot of a plant, has nodes and internodes and is a support for leaves, buds and generative organs. The main function of the stem is leading. The movement of substances occurs along the leading elements: organic (from leaves to all organs) and mineral solutions (from roots to aboveground organs). Spare substances accumulate in the stem; green stems are photosynthetic; through stomata in the skin of the stem and lentils in the cork, the function of gas exchange is carried out. By growth and placement in space, the stems are divided into erect (sunflower), curly (field birch), creeping (white clover), tenacious (grapes). According to the presence of wood, the stems are divided into herbaceous (knotweed, plantain) and woody (birch, oak, currant).
Annual plants live throughout the year or only the favorable season. Biennial plants in the first year of life are exclusively vegetative organs and accumulate nutrients in their underground (carrots, beets, dahlias) or aboveground (cabbage) parts. The next year they form fruits and seeds. Perennial plants live three or more. Among them there are trees, bushes, semi-bushes and herbaceous plants. The stems can have various shapes on a cross section: a circle (linden, poplar), a tetrahedron (sage, mint), a trihedron (sedge), a polyhedron (valerian) or be flattened (opuntia cactus) and others.
Both aboveground and underground shoots can be modified, performing additional functions.
Rhizome - a modified underground shoot that looks like a root; differs from it in the presence of nodes and internodes, axillary buds and the absence of a root cap. The rhizome grows with an apex - the place where the apical bud is located. Every year, new above-ground shoots develop from the buds of the rhizome. The rhizome performs the functions of a reserve, reproduction and distribution of the plant, ensures survival in adverse environmental conditions (wheatgrass, thistle).
The bulb is a very shortened flat shoot-bottom with close succulent leaves. Adventitious roots extend from the bottom. The bulb of tulips, lilies, snowdrops, garlic, onions and other plants. The axillary buds change and turn into daughter bulbs. The bulb performs a reserve function, ensures the reproduction of plants and contributes to survival in an unfavorable period.
Stem tubers - thickening of one or more internodes of the stem. Such thickenings can be both underground (potatoes, Jerusalem artichoke) and aboveground (kohlrabi cabbage). They perform the functions of a supply of nutrients, reproduction, and the transfer of an unfavorable period.
Thorns - a modification of the above-ground shoot (thorn, wild pear, hawthorn). They protect the plant from eating, located in the axils of the leaves.
Stolons are elongated creeping shoots, often with scaly leaves. They live one year and give rise to new individuals (nettle) such shoots in everyday life are called "mustache". Shoots can be modified into tendrils (grapes, pumpkin, melon, cucumber) - curly shoots, wrap around various supports and support the stem in a certain position (support function).
It is an axis (stem) with leaves and buds located on it - the rudiments of new shoots that appear in a certain order on the axis. These rudiments of new shoots ensure the growth of the shoot and its branching, i.e., the formation of a shoot system.
Unlike the root, the shoot is dissected into internodes and nodes, with one or more leaves attached to each node. Internodes can be long, and then the shoots are called elongated; if the internodes are short, the shoots are called shortened. The angle between the stem and the leaf at the point of origin is called the leaf axil. The variety of shoot morphology is also determined by the location of the leaves, the way they are attached, the nature of branching, the type of growth and the biological characteristics of the shoot (its development in the air, underground, in).
In modern plant morphology, the shoot as a whole, as a derivative of a single part of the apical meristem, is taken as a single organ of the same rank as the root. The shoot as a single organ has metamerism, i.e., metameres are well expressed in it, repeating along its longitudinal axis. Each metamere consists of a node with a leaf or leaves extending from it, an axillary bud, and an underlying internode.
The first shoot develops from an embryonic shoot represented by a hypocotyl, cotyledons extending from the cotyledon node, and a bud (apical bud), from which all subsequent metameres of the first, or main, stem are formed.
As long as the apical bud is preserved, the shoot is capable of further growth in length with the formation of new metameres. From the buds located in the axils of the leaves, side shoots develop, each of which has an apical and axillary buds. .
The kidney is covered on the outside with dense leathery scales, under which in the center of the kidney there is a rudimentary stem and small rudimentary leaves. In the axils of these leaves are rudimentary buds, each of which is a shoot. Inside the kidney is the growth center, which ensures the formation of all organs and primary tissues of the shoot.
Buds can be vegetative and generative (floral). A stem with leaves and buds grows from a vegetative bud, an inflorescence or a single flower develops from a generative bud.
branching shoot
The side branches are built and grow in the same way as the main stem. Accordingly, the main stem is called the axis of the first order, the branches developing from its axillary buds are called the axis of the second order, etc.
The degree of branching, the direction of growth of branches and their size determine the appearance of plants, their habit. There are two types of branching: apical and lateral. Apical branching is characterized by the division of the growth cone into two parts, each of which gives rise to an escape. Such branching is called forked, or dichotomous. Dichotomous branching occurs in some bryophytes and lycopods.
Lateral branching develops from axillary buds and may be monopodial or sympodial.
Monopodial branching is characterized by the fact that the growth cone of the main shoot has been functioning for many years, building up the stem and increasing the length of the first-order axis. From the axillary buds, axes of the second order are formed. Monopodial branching is characteristic of gymnosperms (spruce, pine, larch), many woody angiosperms (oak, beech, maple, bird cherry) and many herbaceous rosette plants (plantain, dandelion, clover).
Sympodial branching is due to the death of the upper part of the shoot and the development of a vegetative shoot from the upper axillary bud, which usually continues the main axis (poplar, birch, willow, wild rosemary, lingonberry, cereals, sedges, etc.). Such shoots are called replacement shoots.
False forked branching resembles dichotomous, but is sympodial with opposite leaf arrangement (lilac, dogwood, horse chestnut, etc.).
In the direction of growth, shoots are erect, inclined, drooping, hanging, ascending, recumbent, or creeping, creeping, curly, climbing.
According to the structure and life span of shoots, plants are divided into herbaceous and woody.
According to life expectancy, herbaceous plants can be annuals, biennials and perennials. Annual plants live less than a year. Biennial plants in the first year of life form vegetative organs and accumulate reserve nutrients in the roots; in the second year they bloom and die off after fruiting (carrots, radishes, beets, etc.). Perennial herbaceous plants live for more than two years, they annually develop above-ground shoots from buds. These buds, called renewal buds, are in most cases underground on modified shoots - rhizomes, tubers, bulbs.
Woody plants are characterized by the presence of perennial above-ground, strongly lignified shoots that do not die off for the winter. They are represented by trees and shrubs. The trees have a well-developed main stem - a trunk that usually reaches a great height - and a crown, usually consisting of numerous smaller side branches. In shrubs, the main trunk is short-lived or poorly developed. From the axillary and adnexal buds located at its base, shoots develop that reach significant development (buckthorn, hazel, honeysuckle, etc.).
Shrubs have perennial stems, but their secondary thickening and growth in height are weakly expressed (lingonberries, blueberries, wild rosemary, cranberries, etc.).
In semi-shrubs, the bases of the shoots become woody and persist for several years. The upper parts of the shoots die off by winter. From the axillary buds located on the wintering areas of the shoots, new shoots grow in the spring of next year (some types of wormwood, cinquefoil).
Escape metamorphoses
Plant shoot metamorphoses include various forms of modifications of underground and aboveground shoots.
Underground shoots are formed in the soil, and the nature of their modifications is associated with the accumulation of reserve nutrients in order to survive unfavorable seasons for vegetation - winter, drought, etc. Reserve substances can be deposited in such underground shoots as tubers, bulbs, rhizomes.
Tubers are thickenings of an underground shoot. They usually form in the axils of developing underground colorless scaly leaves called stolons (like potatoes). The apical buds of the stolons thicken, while their axis grows and turns into a tuber, and only the edges remain from the scaly leaves. In the bosom of each eyebrow sit groups of kidneys - eyes. Stolons are easily destroyed, and tubers serve as organs of vegetative reproduction.
The bulb is an underground, strongly shortened shoot. The stem in the bulb occupies a small part and is called the bottom. Grassroots succulent leaves, called scales, are attached to the bottom. The outer scales of the bulb are often dry, leathery, and have a protective function. The upper leaves are in the apical bud of the bottom, which develops into aerial green leaves and into a flower-bearing arrow. Adventitious roots develop from the bottom of the bulb. Bulbs are typical for plants from the Liliaceae family (lilies, tulips, onions, etc.), amaryllis (amaryllis, daffodils, etc.). Most bulbous plants are ephemeroids, which have a very short growing season and live mainly in arid climates.
Rhizome - an underground shoot of a plant that looks like a root or parts of the root system. In the direction of growth, it can be horizontal, oblique or vertical. The rhizome performs the functions of deposition of reserve substances, renewal, sometimes vegetative propagation in perennial plants that do not have a main root in the adult state. The rhizome does not have green leaves, but at least in the young part it has a well-defined metameric structure. The nodes are distinguished by leaf scars, the remains of dry leaves or living scaly leaves and by the location of the axillary buds. According to these features, it differs from the root. Adventitious roots form on the rhizome, lateral branches and above-ground shoots grow from the buds.
The apical part of the rhizome, constantly growing, moves forward and transfers the renewal buds to new points, while the rhizome in the old part gradually dies off. Depending on the intensity of the growth of rhizomes and the predominance of short and long internodes, long-rhizome and short-rhizome plants are distinguished.
Rhizomes, like aboveground shoots, have sympodial or monopodial branching.
When branching the rhizome, daughter rhizomes are formed, which leads to the formation of above-ground shoots. If destruction occurs in separate parts of the rhizome, they are isolated and vegetative reproduction occurs. A set of new individuals formed from one vegetatively is called a clone.
Rhizome formation is characteristic of perennial herbaceous plants, but sometimes it occurs in shrubs (euonymus) and some shrubs (lingonberries, blueberries).
The metamorphoses of plant shoots also include above-ground modifications - these are above-ground stolons and mustaches. In some plants, young shoots begin to grow horizontally on the surface of the soil, like lashes. After some time, the apical bud of such a shoot bends up and gives a rosette. In this case, the whips are destroyed, and the daughter individuals exist independently, the function of these whips is to capture the area and resettle new individuals, that is, they perform the function of vegetative reproduction. Scourges are aboveground stolons that have green leaves and are involved in the process of photosynthesis. They are found in many plants (bone, Zelenchuk, tenacity, etc.). In some plants (strawberries, partly stone fruits), above-ground stolons do not have green leaves, their stems are thin with long internodes. They got the name mustache. Usually, after rooting of their apical bud, they are destroyed.
Other metamorphoses of aboveground shoots of plants include spines of leaf (cactus, barberry) and stem (wild apple, wild pear, barberry, etc.) origin. The formation of spines is associated with the adaptation of plants to a lack of moisture. In addition, in some plants of arid habitats, a flattening of the stem or shoot occurs, the so-called phyllocladia and cladodia (for example, needle needle) are formed. On the shoots of the needle, in the axils of scaly leaves, flat leaf-shaped phylloclades are formed, corresponding to the whole axillary shoot and having limited growth. Cladodia, unlike phyllocladia, are flattened stems that have the ability to grow for a long time. Plant shoots, and sometimes leaves, can turn into tendrils, which, in the process of long apical growth, are able to twist around a support.
During its life cycle, a fruit tree forms various types of shoots and
Types of fruit shoots
1. Spear.
2. Fruit bag. 3 Whorl
buds, and it is important to know their role in the development of the tree in order to be able to regulate their growth and influence the interdependent processes associated with their development.
As already mentioned, the basis for the formation of the skeletal structure of the crown is the central conductor, which is a continuation of the trunk, and skeletal branches or twigs. From skeletal branches develop fouling branches, which are small branches of tree shoots. New growing branches develop every year, and it is not uncommon for annual branches, especially long ones, to be erroneously called shoots. It is necessary to separate these two terms: the growth of the current year is considered to be a shoot, which in fact remains a shoot as long as it bears foliage. As soon as in autumn the already quite lignified shoot sheds foliage, it passes into the category of branches. Overgrown branches are divided into vegetative, or growth, and generative, or fruit.
Vegetative shoots provide an increase in the total mass and dimensions of the tree and differ in origin and functions performed by them in the crown. From the apical buds grow continuation shoots main or overgrowing branches, they are also called gains, as they annually increase the length and thereby replenish the volume of the tree crown.
If the terminal bud blooms in the year of its formation, a young shoot grows from it, called the summer growth. This growth is very delicate, susceptible to frost and therefore undesirable. One or two kidneys located below the apical,
give competing branches. They got their name because they compete for a leading position with legitimate continuation branches in terms of strength of growth and placement. Below are the lateral branches growing respectively from the lateral buds. If the lateral branches are directed inside the crown, then they have developed from internal buds and, therefore, are internal. Outwardly directed branches develop from the external buds and are named accordingly. outdoor branches. It is important to distinguish between them to determine the location and orientation of the branch near which the cut will be made when forming the crown or pruning.
Vegetative shoots
Vegetative shoots are shoots without generative organs, consisting of an axis, leaves and buds. They can be apical and lateral, shortened and elongated. Elongated vegetative shoots are often called growth shoots. In fruit growing, vegetative shoots include continuation shoots, competing, regenerative, top and root shoots.
Vegetative shoots differ from generative shoots in the duration of growth and length. In some fruit crops, such as apple, pear, plum, etc., these differences are clearly expressed, in others they are less noticeable. After the leaves fall, vegetative shoots, depending on the type of buds laid on them, turn into various vegetative and generative branches.
A special position among the vegetative branches is occupied by tops, or water shoots, which are also often called fatty shoots.
Thin, strong, vertically growing young shoots with large internodes are formed in dense crown of a tree that is deficient in light. As a rule, they appear on the perennial parts of large branches from a dormant bud that has not been touched for years. Factors stimulating the formation of tops can be aging of the tree, freezing or damage to the higher part of the branch. Due to poor lighting, tops become useless and can lay a flower bud only when the conditions for their development inside the crown improve, so it is recommended to remove these branches.
top shoots
Top shoots (tops, fatty or water shoots) develop from a dormant bud. They usually form on old parts of perennial branches or on the trunk of a tree during its natural aging. The process of formation of top shoots can be caused by the freezing of a tree, its mechanical damage as a result of improper pruning, hail, wind, etc. Spinning top shoots are characterized by intense, protracted, clearly defined vertical growth, elongated internodes, shadow type of leaves located inside the crown, as well as increased watering and friability of tissues.
Often, near the stem of a tree, branches appear from the ground that have grown from the roots. This so-called root growth, extremely undesirable for a tree, since it is forced to spend additional forces, moisture, nutrients on its completely unproductive parts. Root growth should be destroyed without waiting for its growth.
generative shoots are the constituent elements of the tree crown, on which the flower buds are laid, and are directly involved in the formation of the crop. These branches got their name due to the fact that only generative buds can be placed on them (even if they do not develop in any year), which determine the propensity of generative branches to bear fruit and their purpose for ensuring the harvest.
Generative shoots include:
fruit stick - thin, often downwardly curved annual branch more than 15 cm long with a flower bud at the top;
spear - straight, noticeably tapering towards the apex, a shortened lateral branch 5-15 cm long with a flower bud;
kolchatka - the shortest annual branch up to 2-3 cm long, very fragile with one well-formed leaf or flower bud;
fruits - shoots 2-3 years old, once bearing fruit;
spurs- short fruit formations from 0.5 to 10 cm long;
whorls - short fruit formations only up to 3 cm long with a group of buds at the top.
generative shoots
A generative, or flower-bearing, shoot is a shoot that bears individual flowers or inflorescences, and subsequently fruits. A generative shoot develops from a generative bud that has the beginnings of a flower or inflorescence. Generative shoots can differ greatly from vegetative ones, as, for example, in pome and stone fruits, or differ little, as, for example, in sea buckthorn, honeysuckle and actinidia. According to the ratio of the vegetative and flowering zones, they distinguish:
unspecialized generative shoots, which are characterized by a strong predominance of the vegetative zone and late flowering in the leafy state. This type of generative shoots is typical for actinidia, lemongrass, honeysuckle;
semi-specialized generative shoots, characterized by a clearly defined vegetative zone, apical arrangement of flowers or inflorescences, flowering in a leafy state, which occurs simultaneously with the appearance of leaves or immediately before it. This type of generative shoots is typical for quince, viburnum, apple, pear, mountain ash, chokeberry;
specialized generative shoots, characterized by a strongly reduced vegetative zone. Externally, they are a single shoot or inflorescence, bloom in a leafless state and very early, which often causes damage to the flowers by late spring night frosts.
This type of generative shoots is typical for cherry plums, plums, cherries, sweet cherries, peaches, apricots, and hazelnuts.
fruit bags are thickened formations on a fruit twig, spear or ringlet, which serve to form fruits. When a flower bud awakens, a swelling appears on the generative branch, resembling a bag in shape, which explains its name. From the fruit bag, additional generative shoots can develop in the form of annelids, spears, fruit twigs. Annually growing in length, the generative branches turn into fruits and fruits,
