Wood has a relatively high strength with a small volumetric weight, easy workability, elasticity, low thermal conductivity and frost resistance. Under favorable operating conditions, wood is stored for a very long time.
Thanks to these advantages, along with a relatively low cost, wood has found a very wide application in construction (log and panel walls, partitions, ceilings, roofs, floors, etc.).
However, how construction material wood has some disadvantages. Among them should be indicated:
· structural heterogeneity(anisotropy), which determines the difference in strength and thermal conductivity along and across the fibers, which creates significant difficulties when using wood in construction;
· hygroscopicity, i.e., the ability to absorb and evaporate moisture when the humidity and temperature of the surrounding air change. With increasing humidity, the wood swells (its volume increases), with a decrease in humidity it dries out (its volume decreases). Since, due to the anisotropy, these changes in the dimensions of the wood in different directions are not the same, they cause internal stresses, leading to the formation of cracks and warping;
· decay i.e. the ability to be destroyed by the action of microorganisms, observed in wood that is in adverse conditions;
· combustibility because of which wooden structures are flammable unless special measures are taken to protect them from fire.
Builders must be well aware of both positive and negative building properties wood, in order to be able to mitigate negative properties, and use positive ones to the maximum extent,
The structure of wood can be studied with the naked eye yali at some magnification.
A structure that is visible to the naked eye or at low magnification (through a magnifying glass) is called a macrostructure, and visible only at high magnification (through a microscope) is called a microstructure.
macrostructure
It is most convenient to get acquainted with the macrostructure by three sections of a tree trunk (Fig. 1). A cut by a plane passing along the chord of the cross section at some distance from the axis of the trunk (Fig. 1, a) is called tangential; a plane perpendicular to the axis of the trunk (Fig. 1,b), - transverse or end; a plane passing through the axis of the trunk (Fig. 1, c) - radial.
Rice. 1. Tree cuts
Rice. 2. The structure of the tree according to the end section
When considering the end section of the trunk, it is possible to distinguish the parts shown in Fig. 2. The bark, consisting of the outer layer 1 - crust - and the inner 2 - bast, protects the tree from mechanical damage. In a growing tree, the bast layer serves to carry nutrients down from the crown of the tree; it stores these substances. Under the bast there is a thin layer of cambium 3, consisting of living cells. In the cambium layer, bast cells are deposited towards the bast, and wood cells are deposited towards the center of the tree. Number of wood cells deposited more quantity bast cells, as a result of which the wood grows faster than the bark.
The thick layer of wood behind the cambium consists of a series of thin concentric layers. On the cross section On the trunk of a tree of some species, it is possible to distinguish the outer part of the wood - sapwood 4 - and the inner part - the core 5. The sapwood consists of younger ones, the core - of completely dead cells.
In trees of some species (pine, oak, cedar), the color of the core is darker than the color of sapwood; in others (spruce, fir, beech), the central part of the wood, which has all the properties of the core, does not differ in color from the peripheral and is called ripe wood. There are species (birch, maple, alder), the so-called sapwood, in which the core is absent.
All tree species can be divided into heartwood, having a core and sapwood, sapwood, devoid of a core, having only sapwood, and ripe woody, having ripe wood and sapwood.
Rice. 3. Pine wood cuts
The core 6 is located along the entire trunk in its central part. It consists of cells with thin walls, weakly interconnected. The core and the shoots of wood formed in the first year of existence form a core tube with a diameter of 1 to 10 mm, depending on the species and age of the tree. This part of the trunk is usually the weakest, crumbles easily and rots more easily than others.
On the transverse (end) section of a tree trunk, you can see a large number of concentric layers. Each such layer corresponds to one year of the tree's life, which is why it is called the annual layer, or annual ring.
In spring, thin-walled cells of early wood of the annual ring are formed, in summer - strong thick-walled cells of late wood. On fig. 3 shows radial, end and tangential sections of pine wood; they clearly show the difference in the tissues of early and late wood.
Depending on the growth conditions, the annual layers are of different widths, even in trees of the same species. The width of the annual layers does not affect the properties of wood as much as the percentage of mechanically most valuable late wood in it.
in wood hardwood moisture moves through the vessels / tubs) located along the trunk. On the transverse section of the trunk, they look like rounded holes.
In the wood of some hardwoods (oak, ash, elm), large and small vessels are located; large ones are located in the early part of the annual layer, small ones are collected in groups or distributed evenly over the area of the late part (Fig. 4). Such breeds are called k-plmtevascular.
Rice. 4. Section of the annular vascular rock
In the wood of other hardwood species (birch, aspen, linden), there are no large vessels; there is no sharp difference between the early and late parts of the annual layer. These breeds are called disseminated vascular (Fig. 5).
Rice. 5. Cross-section of the seed-vascular breed
Trees conifers do not have vessels, but consist mainly of closed elongated cells (tracheids). In most conifers, between tracheids (mainly in the late part of the annual layer) there are so-called resin ducts - intercellular spaces filled with resin (see Fig. 3).
In addition to annual rings, on a cross section of a tree, narrow stripes can be seen with the naked eye, directed along the radii and called core rays. In crafts, many tree species are easiest to distinguish precisely by the shape and arrangement of the core rays and the characteristic pattern formed by their section.
microstructure
When examining the microstructure of wood under a microscope, one can see that it consists of a very large number of living and dead cells of various shapes and sizes.
Each living cell has a shell and inside it the protoplasm, cell sap and nucleus. Protoplasm is a plant protein composed of carbon, hydrogen, oxygen, nitrogen and sulfur.
Nucleus on chemical composition very close to protoplasm and differs from it only in the content of phosphorus. Nuclei meet various forms, for the most part oval.
shell cells mainly form a substance called cellulose, or fiber. As the cell grows, a very important change in the shell occurs - lignification, which is caused by the appearance of lignin cell walls in the substance. Wood cells are diverse in shape and purpose. According to their purpose, there are conductive, mechanical and storage cells.
Conductive cells serve mainly to transfer nutrients from roots to branches and leaves. These are the vessels mentioned above and some tracheids.
mechanical cages elongated, have thick walls and narrow internal cavities. They are tightly interconnected and in hardwoods are evenly distributed over the annual layer, which gives the wood greater strength.
In hardwood, the functions of mechanical (supporting) cells are performed by libriform, which makes up the bulk of the trunk, in coniferous wood - tracheids of late wood.
storage cells are found mainly in the medullary rays. They serve to store nutrients and substances and transfer them to living cells in a horizontal direction.
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Parts of a growing tree. woody plants used to get wood materials, are divided by species into two groups - coniferous and deciduous. Coniferous trees are the most widespread in our country; they occupy about 75% of forest areas. Distinctive feature coniferous trees - resinous, needle-shaped and scaly form of leaves (needles) that do not fall (except for larch) for the winter. Deciduous trees have lamellar leaves of various shapes that fall in winter. Hardwoods are divided into two subgroups depending on the hardness of wood: hard hardwoods (oak, beech, ash, etc.), soft hardwoods (linden, aspen, alder, etc.).
In a growing tree, three main parts are distinguished - crown, trunk, roots (Fig ... Each part has a specific purpose in the life of a tree and various industrial applications. The crown is a collection of branches extending from the trunk. In leaves and needles under the influence of sunlight photosynthesis takes place:
From moisture, minerals and carbon dioxide Fig. Parts
organic matter is produced.
The green part of the tree absorbs carbon dioxide from the atmosphere and releases oxygen and moisture into the atmosphere. The roots of a tree absorb water from the soil with dissolved mineral nutrients, store a supply of nutrients, and support the tree in an upright position. The trunk of a tree serves to transfer moisture and nutrients from the roots to the crown, and from the crown to the trunk of organic substances produced by the leaves, as well as to store a supply of nutrients.
Main sections of the trunk. Macroscopic structure of wood. The wood has a layered-fibrous structure, which can be seen on three main sections of the trunk (Fig. a); transverse - in a plane perpendicular to the longitudinal axis of the trunk; radial - in a plane passing through the axis of the barrel; tangential - in a plane not passing through the axis, but parallel to it.
On the transverse section of the trunk, all its elements can be distinguished (Fig.). The core on the transverse section is visible in the form of a spot with a diameter of 2-5 mm. This is a layer of wood that has grown in the first year of life. Round or oval rings are visible around the core - annual rings, i.e. areas of wood that annually grew on the core. Separate stripes diverge from the core along the radii - this is core rays, which in a growing tree perform the function of transferring nutrients from the outer part of the trunk deep into and storing them. Outside, the trunk is covered with bark.
In the bark zone of an adult tree, three layers can be distinguished: the cambial layer adjacent to the wood, the bast layer, and the outer layer.
Rice. Main trunk cuts
cork, or cork. The cortical layer protects the trunk from mechanical and other damage and external influences (temperature, moisture). A stream of organic nutrients produced by the leaves goes down along the bast layer. The cambial layer (cambium) is a thin layer of living cells. In it, the formation of new cells occurs, as a result of which new growth rings are formed annually.
On the cross section of the trunk, you can often find different colors of wood: the central part of the trunk is darker than the peripheral one. If there are two such zones, the inner, darker part is called the core, the outer one is called sapwood. The sapwood serves to conduct moisture and solutes from the roots to the crown and deposit nutrients.
There are knots in the wood of the trunk, which can be seen on all three main cuts. Knots are the bases of the branches of a tree. On a transverse section of a hardwood trunk, one can detect openings of cut vessels. Vessels have the form of tubes of various lengths, they conduct water and salts dissolved in it from the roots to the crown of the tree. Depending on the location of the vessels, hardwoods can be divided into annular vascular (annular pore), in which a ring of large vessels is formed in the early zone, and scattered vascular (scattered pore), in which the vessels are relatively evenly distributed along the annual layer.
In ring-vascular wood species (oak, ash, chestnut, elm, elm, elm, velvet tree, pistachio), annual layers are very clearly visible. In scattered vascular with large vessels ( walnut, persimmons) and small (birch, aspen, alder, beech, maple, plane tree, poplar, willow, mountain ash and pear) there is no sharp difference between the early and late wood zones, so the boundaries between the annual layers are poorly expressed. In some coniferous woods (pine, spruce, larch, cedar), the naked eye can see resin passages - thin channels filled with resin.
Microscopic structure of wood. Wood is made up of cells of various shapes, different sizes performing various functions in plant life. The bulk of the wood has elongated cells located
along the axis of the trunk. In conifers, they are called tracheids, in deciduous - libriform.
There are two types of cells: thin-walled with a small difference between length and width - parenchymal and thick-walled, in which the length is greater than the width - prosenchymal. The tissue from parenchymal cells is softer and looser than the tissue from prosenchymal cells. Parenchymal cells contain a supply of nutrients, prosenchymal cells form a woody tissue that carries the main mechanical load.
In conifers (Fig. a), tracheids occupy 89-95% of the total volume of wood. These are dead cells that have only a shell. Only the last annual layer contains live tracheids, which die off by autumn. Tracheids within one annual layer vary in cross section. In the early zone, which forms in spring, the tracheids are large and more elongated in the radial direction. More cavities inside them serve for a more abundant supply of moisture. By the end of the vegetative period, they decrease and become elongated in cross section in the tangential direction. Tracheids are not isolated from each other. In the walls of two adjoining tracheids there are holes covered with a membrane - pores. Through the pores, moisture and nutrients can be transferred to the neighboring cell.
Between the tracheids are vertical resin canals. They form and store a supply of resin. Horizontal resin ducts run in the medullary rays and intersect with vertical ones. Resin passages make up 0.1-1.1% of the trunk volume. Resin increases the resistance of wood to decay.
Hardwood wood, unlike coniferous wood, has a more complex structure (Fig. b). The main mass of wood is formed by fibers of libriform and vessels running along the axis of the trunk. Vessels are the main water-carrying element of hardwoods. They are long thin-walled tubes formed from short cells connected at the ends. There are holes in the end partitions of the cells. Vessels in wood range from 10% (birch) to 56% (linden) of its total volume. Libriform is the main tissue of the trunk, which perceives mechanical loads. Fibers librifor-
Rice. Schemes of the microscopic structure of wood: a - pines: - annual layer; 2 - multi-row beam with a horizontal resin passage; 3 - it's time; 4 - core beam; 5 - early tracheids; 6 - beam tracheids; 7 - vertical resin passage; 8 - late tracheids; b - oak: - annual layer; 2 - wood parenchyma; 3 - narrow core beam; 4 - vessels; 5 - libriform; 6 - small vessels of the late zone; 7 - wide core beam; 8 - large vessel of the early zone
STRUCTURE AND SECTIONS OF A TREE TRUNK
A growing tree consists of a crown, trunk and roots. During the life of a tree, each of these parts performs its specific functions and has a different industrial application. In pine, the trunk volume is 65-77%, roots - 15-25, branches - 8-10%; in a birch, the trunk occupies 78-90%, the roots - 5-12, the branches - 5-10%.
The crown consists of branches and leaves (or needles). From carbon dioxide absorbed from the air and water obtained from the soil, complex organic substances are formed in the leaves, which are necessary for the life of the tree. The industrial use of the crown is small. Vitamin flour is obtained from the leaves (needles) - a valuable product for animal husbandry and poultry farming, medications, from branches - technological chips for the production of containerboard and fibreboard.
The trunk is the part of the tree from the roots to the top that carries the branches. The trunk of a growing tree conducts water with dissolved minerals upwards (ascending current), and with organic substances - down the bark to the roots (descending current); stores spare nutrients; serves to accommodate and maintain the crown. It gives the bulk of the wood (from 50 to 90% of the volume of the whole tree) and is of major industrial importance. The upper thin part of the trunk is called the top, the lower thick part is called the butt.
Roots conduct water and minerals dissolved in it up the trunk, store nutrient reserves, and hold the tree upright. The roots are used as a second-rate fuel. Stumps and large roots of pine, some time after felling trees, serve as raw materials for obtaining rosin and turpentine.
Main cuts of a tree trunk
A transverse section is a cut that runs perpendicular to the axis of the trunk and the direction of the fibers and forms an end plane. A radial cut is a longitudinal cut along the axis of the trunk through its core. A tangential cut is a longitudinal cut passing at some distance from the core. The wood on these cuts has different kind and texture.
On the cross section of the trunk, the core, bark and wood with its annual layers are visible.
The core is a narrow central part of the trunk and branches of woody plants, representing a loose tissue. On the end section, it looks like a dark (or other) color spot with a diameter of 2-5 mm. On a radial section, the core is visible in the form of a straight or sinuous dark narrow strip.
The bark covers the tree in a continuous ring and consists of the outer layer - the crust and the inner layer - the bast, which conducts water with organic substances produced in the leaves down the trunk. The bark protects the tree from mechanical damage, sudden changes in temperature, insects and other harmful environmental influences.
The type and color of the bark depends on the age and type of tree. In young trees, the bark is smooth, cracks appear in the bark with age. The bark can be smooth (fir), scaly (pine), fibrous (juniper), warty (euonymus). The color of the bark has many shades.
Depending on the species, age of the tree and growing conditions, our forest species have bark from 6 to 25% of the trunk volume, for example: spruce - 10%, oak - 18%, birch - 15%. bark of many tree species has great practical application. It is used for tanning leather, making floats, corks, heat-insulating and building boards. Bast, matting, ropes, etc. are made from the bast of the bark. chemical substances used in medicine. Birch bark serves as a raw material for tar. Between the bark and the wood there is a very thin, juicy layer not visible to the naked eye - the cambium, consisting of living cells. Cells of wood and bark are formed from cambial cells,
moreover, cells are deposited towards the wood more often (5-6 times) than towards the bark.
Wood in a growing tree occupies most of the trunk and is of major industrial importance. Wood is a collection of conductive mechanical and storage tissues located in the trunks, branches and roots of woody plants between the bark and the core.
Sapwood, heartwood, mature wood
Wood of forest species is usually painted in a light color. At the same time, in some species, the entire mass of wood is painted in one color (alder, birch, hornbeam), in others the central part has a darker color (oak, larch, pine). The dark-colored central part of the trunk is called the core, and the light peripheral part, located between the cambium and the core or ripe wood, is called sapwood. The core of the wood is physiologically inactive, the sapwood is the active part in the growing tree.
In the case when the central part of the trunk has a lower water content, that is, it is drier, it is called ripe wood, and the rocks are called ripe wood. Rocks with a core are called sound. The rest of the rocks, which do not have a difference between the central and peripheral parts of the trunk, either in color or in water content, are called sapwood (non-core).
Of the tree species, the core is: coniferous - pine, larch, cedar; deciduous - oak, ash, elm, poplar. Mature woody species are spruce and fir from conifers, beech and aspen from deciduous species. Sapwood includes hardwoods: birch, maple, hornbeam, boxwood.
However, in some non-core species (birch, beech, aspen, spruce, maple), a darkening of the central part of the trunk is observed. In this case, the dark central zone is called a false core, i.e., irregular nucleation takes place.
Young trees of all species do not have a core and consist of sapwood. Only with the passage of time is the core formed due to the transition of sapwood into sound wood. The core is formed due to the death of living cells of wood, blockage of waterways, deposition of tannins, dyes, resin, calcium carbonate. As a result, the color of the wood, its mass and performance change. mechanical properties. The width of the sapwood varies depending on the breed, growing conditions. In some species, the core is formed in the third year (yew, black locust), in others - in the 30-35th year (pine). Therefore, the sapwood of a yew is narrow, while that of a pine is wide.
The transition from sapwood to the heartwood can be abrupt (larch, yew) or smooth (walnut, cedar). In a growing tree, the sapwood serves to conduct water with minerals from the roots to the leaves, and the core performs a mechanical function. Sapwood wood easily passes water, is less resistant to decay, therefore, the use of sapwood is limited in the manufacture of containers for liquid.
Annual layers, early and late wood.
The cross section shows concentric layers (circles) located around the core. These formations represent the annual growth of timber. They are called annual layers. On the radial section, the annual layers look like longitudinal stripes, on the tangential section - cone-shaped winding lines. Annual layers grow annually from the center to the periphery, and the outer layer is the youngest. The age of the tree can be determined by the number of annual layers on the end section on the butt.
The width of the annual layers depends on the breed, growth conditions, position in the trunk. In some species (fast-growing) the annual layers are wide (poplar, willow), in others they are narrow (boxwood, yew). The narrowest annual layers are located in the lower part of the trunk; up the trunk, the width of the layers increases, since the tree grows both in thickness and in height, which brings the shape of the trunk closer to the cylinder.
In the same breed, the width of the annual layers may be different. Under unfavorable growth conditions (drought, frost, lack of nutrients, waterlogged soils), narrow annual layers are formed.
Sometimes, on two opposite sides of the trunk, the annual layers have an unequal width. For example, trees growing on the edge of the forest, on the side,
facing the light, the annual layers have a large width. As a result, the core of such trees is shifted to the side and the trunk has an eccentric structure.
Some breeds have irregular shape annual layers. So, on the cross section of the hornbeam, yew, juniper, the waviness of the annual layers is observed.
Each annual layer consists of two parts - early and late wood: early wood (internal) facing the core, light and soft; late wood (outer) facing the bark, dark and hard. The difference between early and late wood is clear in conifers and some hardwoods. Early wood is formed in early summer and serves to carry water up the trunk; late wood is deposited towards the end of summer and has a mainly mechanical function. Its density and mechanical properties depend on the amount of late wood.
Core beams of wood
On the cross section of some rocks, light, often shiny, lines directed from the core to the bark are clearly visible - core rays. All breeds have them, but only a few are visible. In width, the core rays can be very narrow, but still visible (in boxwood, birch, aspen, pear and all conifers), narrow (5-100 microns), difficult to distinguish (in maple, elm, elm, linden), wide (100-1000 microns), clearly visible on the transverse and other sections (in oak, beech). Along with the wide ones, false wide ones are also distinguished - bunches of closely lying narrow rays (in hornbeam, alder, hazel).
On a radial section, the core rays are visible in the form of light shiny stripes or ribbons located across the fibers. They can be lighter or darker than the surrounding wood. On a tangential section, the core rays are visible in the form of dark strokes with pointed ends or in the form of lenticular stripes along the fibers. The beam width ranges from 0.015 to 0.6 mm. In felled wood, core rays create beautiful drawing(on a radial section), which is important when choosing wood as decorative material. In a growing tree, the medullary rays serve to carry juices in a horizontal direction and to store reserve nutrients.
The number of core rays depends on the species: hardwoods have about 2-3 times more core rays than conifers.
Vessels of wood
On the transverse (end) section of hardwood, holes are visible, representing sections of vessels - tubes, channels different sizes designed for holding juices. By size, the vessels are divided into large, clearly visible, and small, not visible to the naked eye. Large vessels are most often located in early wood in annual layers and form a continuous ring of vessels on a transverse section. Hardwoods with a continuous ring of vessels are called ring-vascular. In ring-vascular species, in late wood, small vessels are collected in groups, clearly visible due to their light color. If small and large vessels are evenly distributed over the entire width of the annual layer, then such hardwoods are called scattered vascular.
In annular hardwoods, the annual rings are clearly visible due to the sharp difference between earlywood and latewood. In deciduous diffusely vascular species, such a difference between early and late wood is not observed, and therefore annual rings are poorly visible.
On radial and tangential sections, the vessels look like longitudinal grooves. The volume of vessels, depending on the breed, ranges from 7 to 43%.
Resin passages of wood
A characteristic feature of the structure of coniferous wood is resin passages, which are thin narrow channels filled with resin. There are vertical and horizontal resin ducts. On the transverse section, vertical resin ducts are visible as light dots located in the late wood of the annual layer; on longitudinal sections, resin ducts are visible as dark strokes directed along the axis of the trunk. The number and size of resin passages depend on the type of wood. In pine wood, resin passages are large and numerous, in larch wood - small and few.
Resin ducts occupy a small volume of trunk wood (0.2-0.7%) and therefore do not have a significant effect on the properties of wood. They are important when tapping, when resin (resin) is obtained from growing trees.
Each fruit plant consists of an upper (aerial) and a lower (root or underground part). The boundary horizon, the line separating these two spheres by the root neck. They are guided by the root neck when planting tree seedlings, control the planting depth. The upper part of the tree consists of: the main trunk, large large and small branches bearing leaves, buds, flowers and many fruits.
The structure of a fruit tree.
A - above-ground part:
1 - trunk;
2 - root neck;
3 - stem;
4 - central conductor;
5 - continuation branch;
7 - branches of the second order;
8 - branches of the third order;
9 - overgrowing branches;
B - root system:
1 - tap root;
2 - skeletal roots;
3 - semi-skeletal roots;
4 - horizontal roots;
5 - vertical roots;
Tree trunk- the main central part of the fruit plant from the beginning of the root collar to the very top.
Shtamb- the lower region of the trunk tree, without branches and offshoots.
Center Tree Explorer- part of the trunk, on which there are branches exclusively of the first order; these are large branches, branches of the second order grow from them, then the third, etc. Large, large branches of trees related to the branches of the first order are the skeletal components of the skeletal base of the tree, the main branches, the branches that we consider the second order to be semi-skeletal, small branches - growing.
Crown includes a trunk, main skeletal, additional semi-skeletal and many overgrown branches. The latter are growth and fruitful.
Growth (vegetative) branches- annual formations various types, called shoots, (spring, fat, thickening, replacement, competitors).
spring shoots- leafy stems formed in the current vegetative period and constituting the annual growth of the branch. Buds are laid in the axils of the leaves. Shoots that grow from the apical bud are called continuation shoots.
Fat shoots (tops)- originate in dormant buds, on branches of perennial wood of a tree, in case of breaking branches or during heavy pruning.
replacement shoots- develop from mixed types of buds in trees belonging to seed species.
Thickening shoots- are on the trunk.
Competitors- grow from buds adjacent to the continuation shoot, are located at a distance close to it, differ in sharp angles of discharge.
coppice shoots- formed on the adventitious buds of the roots.
Fruitful (generative) branches - different ages education. Pome tree species have fruit twigs in the structure of the plant, which are the obligatory components of the branch system of the tree, spear and ringworm; they are (simple and complex) - elements of the tree.
fruit twigs- one-year branches without branching, 15 cm or more in size, at the end of which there is a generative bud.
spear- small annual branches without branching, 3-12 cm in size, often ending in a generation bud or a thorn.
Ringworms are simple- small fruit branches without branches 0.5-3 cm in size.
Ringworms are complex- fruit ramifications on spears and simple annelids, have several fruit twigs. In stone fruits, fruit-bearing formations are bouquet and mixed branches, as well as spurs. On bouquet flowers, generative buds are located in the form of a bouquet, there is a vegetative bud in the center.
Mixed tree branches- annual increments, consisting of generative and vegetative lateral buds.
Spurs- these are branches up to 10 cm, on which generative buds are located. There are a lot of them on apricots, plums, thorns.
tree leaves- main part fruit plants from how they absorb solar energy depends on the productivity of the tree and the quality of the fruit.
kidneys- the beginnings of future vegetative and generative formations that are in the embryonic state.
At the fruit trees different types kidneys: vegetative (growth), generative (flowering) and mixed (vegetative-generative). According to the place of formation, axillary and adnexal buds are distinguished, according to their location - apical and lateral, according to the time of awakening - normal, germinating in the spring next year, early ripening - in the year of their formation, dormant - not germinated and capable of germination for a long time.
flowers fruit plants are bisexual with stamens and pistils (seed-bearing, stone-bearing); same-sex - with a pistil or only with stamens (nut-bearing). If pistillate and staminate flowers are located separately on one plant, then they are called monoecious (walnut), but if on different ones - dioecious (sea buckthorn).
bisexual flowers on the fruit trees pollinated with the help of insects, heterosexual (nut) - by wind and partially by insects. The fruits of fruit and berry plants are divided into apples, drupes, berries and nuts.
Apple- pulp formed from a two-layer pericarp.
drupes- a fruit, in which the edible part contains the juicy walls of the grown ovary.
Berry- juicy pericarp. A nut is a fruit with a hard dry shell and an edible seed.
The underground part of the tree structure.
A - above-ground part:
1 - trunk;
2 - root neck;
3 - stem;
4 - central conductor;
5 - continuation branch;
6 - skeletal branches of the first order;
7 - branches of the second order;
8 - branches of the third order;
9 - overgrowing branches;
B - root system:
1 - tap root;
2 - skeletal roots;
3 - semi-skeletal roots;
4 - horizontal roots;
5 - vertical roots;
6 - overgrowing roots (lobes)
underground part of the tree is the root system with all its branches. It consists of the main root (tap), skeletal types of roots, semi-skeletal and overgrowing roots.
overgrowing roots- branch strongly and end in small roots up to 3 mm thick and up to several centimeters long, they are called root lobes.
Roots penetrating in the depth of the soil (up to 6-8 m), called vertical; part of the thick roots growing horizontally and with some deviations - horizontal. The functions of performance, the morphological and anatomical structure of the roots divide them into separate classes of roots: conductive, growth roots, transitional, absorbing.
Roots growth (axial) white color, short, growing rapidly, have lateral roots, perform the functions of absorbing moisture and nutrients from the soil.
absorbing roots(sucking, active) growing roots white color, fragile, transparent, 0.1-4 mm in size and 0.3-3 mm thick, quickly die off and are renewed. These are the roots - the most numerous group of the root system. Their main job is absorption and suction from the soil required amount water, as well as biological mineral substances, their processing into active organic compounds.
transitional roots- these are in the past growth or absorbing roots, they have changed color to gray-light or brown.
Conductive roots- continuation of growth and transitional roots. Their main task is to hold trees in the soil, distill water and release nutrients to the upper (aerial region of the tree) from the roots and inverse function absorption of the products of the photosynthesis process. They serve as a reservoir of nutrients. They synthesize a number of compounds.
fruit plant is a complex plant organism. The aboveground and underground parts in the life of a plant perform various special functions and are inextricably interconnected with each other. If you make a cross cut of the trunk, then you can distinguish the following parts: in the center - the core, around it - wood, and along the edges - bark.
tree core- central inner part stem structures with loose tissue.
wood roots, trunk, trunk and the entire crown is the main support of the plant. In the wood (peripheral part) there is a vascular-conducting system, through which water, together with nutrients, move from the roots to the leaves, then they are grouped with carbon dioxide in the air under the influence of the sun and are processed into plastic substances (products of photosynthesis).
Bark covers all parts of the tree and protects above-ground part plants from fluctuations in temperature, high evaporation, damage by pests and diseases. Under the bark there is a thin layer of skin, behind which the bast tissues are placed.
Lub consists of the main tissue, bast fibers and sieve tubes, through which the products of photosynthesis move from the leaves down to the roots and to all parts of the plant.
Between the bast and the wood is a thin layer, difficult to see with the naked eye, called the cambium. During the growing season, it forms new cells of wood and bast. Cambium must be distinguished between vaccinations and re-vaccinations when correct connection The cambium of the grafted stock and scion contributes to the successful survival of the grafted components.
A growing tree consists of three main parts: roots, trunk and crown.
Tree roots absorb water from the soil along with mineral nutrients dissolved in it. Thick roots branch into thinner ones and capillaries, which often extend beyond the crown in the soil (Fig. 1).
The structure of the tree and the scheme of its nutrition
The trunk carries water and mineral nutrients from the roots to the branches and leaves. This movement is called the upward flow of sap flow.
The crown consists of branches and leaves or needles. Part of the water from the root system evaporates through the leaves. The rest of the water, with mineral nutrients dissolved in it, under the influence of sunlight and heat, forms organic nutrients necessary for the growth of the tree. Leaves absorb carbon dioxide from the air, which breaks down into carbon and oxygen. Oxygen is released into the air, which is why deciduous trees in cities are called the "lungs of the city". Organic nutrients formed in the leaves, along the inner part of the bark, called the bast, come down and spread throughout the tree. This is the so-called downward flow of sap flow.
The trunk is the main and most valuable part of the tree, giving 60...90% business wood. The thin part of the trunk is called the top, the thick part is called the butt. The structure of a tree trunk, visible to the naked eye, is called a macrostructure. It is clearly visible on three main sections of the trunk.
There is an end cut perpendicular to the longitudinal axis of the trunk (Fig. 2), a radial cut perpendicular to the end cut and passing through the core of the trunk; tangential section passing tangentially to the annual layers at some distance from the core.
Main trunk cuts
The structure and properties of wood are not the same in different cuts. On the transverse section of the trunk, the bark, its cork and bast layers, and the cambium are distinguished; visible wood, its sapwood and core, where the annual layers, core rays and core are different (Fig. 3).
Cross section of the trunk and its components
The core is located in the center of the tree trunk along its entire length. It has a loose structure, is fragile and is subject to rapid decay. In conifers, the diameter of the core is 3-4 cm, while in hardwoods it is slightly larger. Each year, wood growth occurs by one annual ring formed by the cambium under the bark.
With the growth of the tree, the wood of the core is destroyed, so its diameter gradually increases towards the crown. In some species, such as pine, larch, oak, ash and cedar, the part of the wood located closer to the core has a darker color and low humidity. This most valuable part of the wood is called the core, and the rest, located towards the bark, is called sapwood. There are species that do not have a core, they have the same color of wood throughout the section.
The wood of the core is distinguished by strength, density and hardness, as well as greater resistance to decay than sapwood, which consists of young cells, which are characterized by a lower density of wood. Sap flow - the movement of water with nutrients dissolved in it - occurs along the sapwood. The thickness of the sapwood depends on the type of tree, its age and growing conditions. The growth of the core with the death of the sapwood cells turns into the wood of the core.
In birch, beech, maple, aspen and alder, the center of the trunk has a dark color, indicating the initial stage of decay. This part of the trunk is called the false core.
Between the sapwood and the bark is a thin layer of living cells - the cambium. During the growing season, the division of cambial cells forms new wood and bark cells. At the same time, the tree grows both in thickness and in length. The bark consists of an outer cork layer and an inner bast layer.
The outer layer protects the tree from atmospheric influences and mechanical damage, while the inner layer transfers organic nutrients developed in the crown leaves down the trunk.
Most conifers in the cross section of the trunk have different annual layers in the form of concentric circles. Annually, with normal growth, one annual layer is formed. Its thickness (in the direction of the radius) is different for different tree species. The early wood of the annual core layer differs from the late wood, which is closer to the bark. This is explained by the growth of the early wood of the annual layer in spring and early summer. At this time, there is little moisture in the soil and the cells of early wood are loose and light, providing sap flow. The late wood of the annual layer grows in late summer and autumn.
In hardwoods, the cells of late wood (annual layer) consist of supporting tissues, and in conifers, they consist of thick-walled tracheids, darker in color and distinguished by density and strength.
The width of the annual layers depends on the age of the tree, on the species and growth conditions. In young trees, the annual layers are usually wider, except for the willow, which has only narrow annual layers. In the pine growing in the north, the annual layers are narrower than in the pine growing in the southern latitudes. The properties of wood are characterized by the width of the annual layers. Conifers with narrow annual layers are more durable and resinous.
Pine with narrow annual layers of red-brown color is more valuable than with wide annual layers. Coniferous wood, on the end section of which in the radial direction of 1 cm there are at least three and no more than 25 annual layers, is considered the best. In hardwood species, on the contrary, the wider the annual layers, the denser, harder and more durable wood. This is typical for oak, chestnut, elm, ash, elm. These breeds have spring period regardless of climatic, soil and other conditions, 2 ... 3 rows of large conductive tissue (tracheids) are formed, and then - the late wood of the annual layer, consisting of mechanically strong tissues.
In birch, beech, hornbeam, maple, linden, alder, aspen, the wood does not have pronounced annual layers and the width of the annual layer does not affect the quality of the wood.
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