Wood is hard, fibrous, lignified structural tissue produced as secondary xylem in the stems of woody plants, notably trees but also shrubs. Hardness refers to various properties of Matter in the Solid phase that give it high resistance to various kinds of shape change when Force In Vascular plants xylem is one of the two types of transport tissue Phloem being the other A woody plant is any vascular Plant that has a perennial stem that is above ground and covered by a layer of thickened Bark. A tree is a perennial Woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or A shrub or Bush is a horticultural rather than strictly botanical category of Woody plant, distinguished from a Tree It conducts water to the leaves and other growing tissues and acts as a support function, enabling plants to reach large sizes. Wood may also refer to other plant materials and tissues with comparable properties.

Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. Heterogeneous is an adjective used to describe an object or system consisting of multiple items having a large number of structural variations Hygroscopy is the ability of a substance to attract Water Molecules from the surrounding environment through either absorption or Adsorption The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called Anisotropy (pronounced with stress on the third syllable ˌænaɪˈsɒtrəpi is the property of being directionally dependent as opposed to Isotropy, which means homogeneity It is composed of fibers of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%). Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 A hemicellulose can be any of several Heteropolymers (matrix polysaccharides present in almost all plant cell walls along with Cellulose. Lignin or lignen is a complex Chemical compound most commonly derived from Wood and an integral part of the secondary Cell walls of Plants ^[1]

Sections of tree trunk

A tree trunk as found at the Veluwe, The Netherlands

Artists can use wood to create delicate sculptures. The Veluwe is a forest-rich ridge of hills in the province of Gelderland in the Netherlands. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands The definition of an artist is wide-ranging and covers a broad spectrum of Activities to do with creating Art, practicing the Arts and/or demonstrating

Wood can be cut into straight planks and made into a hardwood floor (parquetry). The term hardwood is used to describe Wood from broad-leaved angiosperm Trees mostly Deciduous, but not necessarily in the case of tropical A floor is the walking surface of a room or vehicle Floors vary from simple dirt in a cave to many-layered surfaces using modern technology

Wood has been used for millennia for many purposes. One of its primary uses is as fuel. Fuel is any material that is burned or altered in order to obtain energy It is also used as for making artworks, furniture, tools and weapons, and as a construction material. Furniture is the Mass noun for the movable objects which may support the human body (seating furniture and beds, provide storage or hold objects on horizontal A broader definition of a tool is an entity used to interface between two or more domains that facilitates more effective action of one domain upon the other A weapon is a Tool used either in Hunting, or attack or defence in Combat for the purpose of subduing enemy personnel or to destroy enemy weapons In the fields of Architecture and Civil engineering, construction is a process that consists of the Building or assembling of Infrastructure

Wood has been an important construction material since humans began building shelters, houses and boats. House generally refers to a Shelter or Building that is a Dwelling or place for Habitation by Human beings. A boat is a Watercraft of modest size designed to float or plane on water and provide transport over it Nearly all boats were made out of wood till the late 1800s, and wood remains in common use today in boat construction. Year -of the Julian calendar. The Gregorian calendar was 11 days ahead of the Julian calendar until Friday, but 12 days ahead since Saturday. New domestic housing in many parts of the world today is commonly made from timber-framed construction. In buildings made of other materials, wood will still be found as a supporting material, especially in roof construction, in interior doors and their frames, and as exterior cladding. Vietnam roofjpg|thumb|The roofs of Vietnam.]] A roof is the covering on the uppermost part of a Building. Wood to be used for construction work is commonly known as lumber in North America. Lumber or timber is Wood in any of its stages from felling through readiness for use as structural Material for Construction, or Elsewhere, lumber usually refers to felled trees, and the word for sawn planks ready for use is timber.

Wood unsuitable for construction in its native form may be broken down mechanically (into fibres or chips) or chemically (into cellulose) and used as a raw material for other building materials such as chipboard, engineered wood, hardboard, medium-density fiberboard (MDF), oriented strand board (OSB). Particle board, or particleboard, (called "chipboard" in some countries is an Engineered wood product manufactured from Wood particles such Engineered wood, also called composite wood, "man made wood" or "manufactured wood" includes a range of derivative Wood products which are Hardboard, also called high-density fiberboard, is a type of Fiberboard, which is an Engineered wood product Medium-density fiberboard ( MDF or MDFB) is an Engineered wood product formed by breaking down Softwood into Wood fibers often in Oriented strand board, or OSB, or waferboard or Sterling board (UK is an Engineered wood product formed by layering strands (flakes of Such wood derivatives are widely used: wood fibers are an important component of most paper, and cellulose is used as a component of some synthetic materials. Paper is thin material mainly used for writing upon printing upon or packaging Wood derivatives can also be used for kinds of flooring, for example laminate flooring. Laminate flooring is type of Flooring made of a Laminate material

Wood is also used for cutlery, such as chopsticks, toothpicks, and other utensils, like the wooden spoon. A toothpick is a small stick of Wood, Plastic, Bamboo, Metal or other substance used to remove detritus from the Teeth, usually after

Formation

A tree increases in diameter by the formation, between the old wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the Bark, also known as periderm is the outermost layer of stems and Roots of Woody plants such as Trees It overlays the Wood and consists Where there are clear seasons, this can happen in a discrete pattern, leading to what is known as growth rings, as can be seen on the end of a log. Dendrochronology (from Greek grc δένδρον dendron, "tree" grc χρόνος khronos, "time" and grc -λογία If these seasons are annual these growth rings are annual rings. Where there is no seasonal difference growth rings are likely to be indistinct or absent.

Within a growth ring it may be possible to see two parts. The part nearest the center of the tree is more open textured and almost invariably lighter in colour than that near the outer portion of the ring. Texture refers to the properties held and sensations caused by the external surface of objects received through the sense of touch. The inner portion is formed early in the season, when growth is comparatively rapid; it is known as early wood or spring wood. The outer portion is the late wood or summer wood, being produced in the summer. ^[2] In white pines there is not much contrast in the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. There are three main subgenera of '''''Pinus''''', the subgenus Strobus ( White pines or soft pines the subgenus Ducampopinus ( In hard pines, on the other hand, the late wood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored early wood. There are three main subgenera of '''''Pinus''''', the subgenus Strobus ( White pines or soft pines the subgenus Ducampopinus ( In ring-porous woods each season's growth is always well defined, because the large pores of the spring abut on the denser tissue of the fall before. In the diffuse-porous woods, the demarcation between rings is not always so clear and in some cases is almost (if not entirely) invisible to the unaided eye.

Knots

A knot on a tree at the Garden of the Gods public park in Colorado Springs, Colorado (October 2006). For the Garden of the Gods in Southern Illinois, see Shawnee National Forest. The City of Colorado Springs is a Home Rule Municipality that is the County seat and most populous city of El Paso County, Colorado, The State of Colorado ( or chiefly by nonresidents) is a state located in the Rocky Mountain region of the United States of America.

A knot is a particular type of imperfection in a piece of timber, which reduces its strength, but which may be exploited for artistic effect. In a longitudinally-sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the roughly parallel fibres (grain) of the rest of the "flows" (parts and rejoins). Wood grain describes the alignment texture and appearance of the Wood fibres

A knot is actually a portion of a side branch (or a dormant bud) included in the wood of the stem or larger branch. A branch ( American English ˈbræntʃ British English ˈbrɑːntʃ or tree branch (sometimes referred to in Botany as a ramus The included portion is irregularly conical in shape (hence the roughly circular cross-section) with the tip at the point in stem diameter at which the plant's cambium was located when the branch formed as a bud. Within a knot, the fibre direction (grain) is up to 90 degrees different from the fibres of the stem, thus producing local cross grain.

During the development of a tree, the lower limbs often die, but may persist for a time, sometimes years. Subsequent layers of growth of the attaching stem are no longer intimately joined with the dead limb, but are grown around it. Hence, dead branches produce knots which are not attached, and likely to drop out after the tree has been sawn into boards.

In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.

Knots materially affect cracking (known in the industry as checking) and warping, ease in working, and cleavability of timber. They are defects which weaken timber and lower its value for structural purposes where strength is an important consideration. The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and/or tension than where under load along the grain and/or compression. In Physics String Tension is the magnitude of the pulling force exerted by a string cable chain or similar object on another object Physical compression is the result of the subjection of a material to Compressive stress, resulting in reduction of Volume. The extent to which knots affect the strength of a beam depends upon their position, size, number, direction of fiber, and condition. Fiber or fibre is a class of Materials that are continuous filaments or are in discrete elongated pieces similar to lengths of thread. A knot on the upper side is compressed, while one on the lower side is subjected to tension. If there is a season check in the knot, as is often the case, it will offer little resistance to this tensile stress. Small knots, however, may be located along the neutral plane of a beam and increase the strength by preventing longitudinal shearing. A shear stress, denoted \tau\ ( Tau) is defined as a stress which is applied Parallel or tangential to a face of a material Knots in a board or plank are least injurious when they extend through it at right angles to its broadest surface. Knots which occur near the ends of a beam do not weaken it. Sound knots which occur in the central portion one-fourth the height of the beam from either edge are not serious defects.

Knots do not necessarily influence the stiffness of structural timber. Only defects of the most serious character affect the elastic limit of beams. Stiffness and elastic strength are more dependent upon the quality of the wood fiber than upon defects in the beam. The effect of knots is to reduce the difference between the fiber stress at elastic limit and the modulus of rupture of beams. In Solid mechanics, Young's modulus (E is a measure of the Stiffness of an isotropic elastic material The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to the grain.

For purposes for which appearance is more important than strength, such as wall panelling, knots are considered a benefit, as they add visual texture to the wood, giving it a more interesting appearance.

The traditional style of playing the Basque xylophon txalaparta involves hitting the right knots to obtain different tones. The txalaparta (IPA or) is a specialized Basque music device of Wood or stone, similar to Romanian Toacă.

Heartwood and sapwood

A section of a Yew branch showing 27 annual growth rings, pale sapwood and dark heartwood, and pith (centre dark spot). Taxus is a Genus of yews small coniferous Trees or Shrubs in the yew family Taxaceae. Pith is a light substance that is found in Vascular plants It consists of soft spongy Parenchyma cells and is located in the center of the stem. The dark radial lines are small knots.

Heartwood is wood that has died and become resistant to decay as a result of genetically programmed processes. It appears in a cross-section as a discolored circle, following annual rings in shape. Heartwood is usually much darker than living wood, and forms with age. Many woody plants do not form heartwood, but other processes, such as decay, can discolor wood in similar ways, leading to confusion. Some uncertainty still exists as to whether heartwood is truly dead, as it can still chemically react to decay organisms, but only once (Shigo 1986, 54).

Sapwood is living wood in the growing tree. All wood in a tree is first formed as sapwood. Its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the food prepared in the leaves. ROOT is an object-oriented program and library developed by CERN. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees grown in the open may become of considerable size, 30 cm or more in diameter, before any heartwood begins to form, for example, in second-growth hickory, or open-grown pines. Trees in the genus Carya (from Ancient Greek κάρυον " Nut " are commonly known as Hickory. This article is about the tree For other uses of the term "pine" see Pine (disambiguation.

The term heartwood derives solely from its position and not from any vital importance to the tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such trees as chestnut, black locust, mulberry, osage-orange, and sassafras, while in maple, ash, hickory, hackberry, beech, and pine, thick sapwood is the rule. Chestnut ( Castanea) (including some chinkapin or Chinquapin) is a Genus of eight or nine Species of Deciduous Black Locust ( Robinia pseudoacacia) is a Tree in the subfamily Faboideae of the pea family Fabaceae. The species is dioeceous, with male and female Flowers on different plants Sassafras is a genus of three Sassafras trees grow from 15–35 m (50–120 feet tall and 70–150 cm (2 Acer ( maple) is a Genus of Trees or Shrubs They are variously classified in a family of their own the Aceraceae, or An ash can be any of four different tree genera from four very distinct families; most commonly in a combined form (e For the German Renaissance scholar see Conrad Celtes. For the town see Celtis Missouri. For the babyfood see Beech-Nut. Beech ( Fagus) is a genus of ten Species of Deciduous Trees in the

There is no definite relation between the annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is thicker in the upper portion of the trunk of a tree than near the base, because the age and the diameter of the upper sections are less.

When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will however remain as knots. No matter how smooth and clear a log is on the outside, it is more or less knotty near the middle. Consequently the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that sapwood, because of its position in the tree, may have certain advantages over heartwood.

It is remarkable that the inner heartwood of old trees remains as sound as it usually does, since in many cases it is hundreds of years, and in a few instances thousands of years, old. Every broken limb or root, or deep wound from fire, insects, or falling timber, may afford an entrance for decay, which, once started, may penetrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of weakness. Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position.

If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon the competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks, maintain the same width of ring for hundreds of years. The term oak can be used as part of the common name of any of about 400 species of Trees and Shrubs in the Genus Quercus (from Latin Upon the whole, however, as a tree gets larger in diameter the width of the growth rings decreases.

There may be decided differences in the grain of heartwood and sapwood cut from a large tree, particularly one that is mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even-textured than that produced earlier, but in other species, the reverse applies. In a large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness, strength, and toughness to equally sound heartwood from the same log. Hardness refers to various properties of Matter in the Solid phase that give it high resistance to various kinds of shape change when Force In Materials science, the strength of a material refers to the material's ability to resist an applied force

Different woods

There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it. For every tree species there is a range of density for the wood it yields. There is a rough correlation between density of a wood and its strength (mechanical properties). For example, while mahogany is a medium-dense hardwood which is excellent for fine furniture crafting, balsa is light, making it useful for model building. The name mahogany is used when referring to numerous varieties of dark-colored wood originally the wood of the species Swietenia mahagoni, known as West See also Scale model A physical model is a smaller or larger physical copy of an object The densest wood may be black ironwood. Olea laurifolia ( Black Ironwood) is a Species of Flowering plant belonging to the Olive family Oleaceae

Wood is commonly classified as either softwood or hardwood. Softwood is a generic term used in Woodworking and the Lumber industries for Wood from Conifers (needle-bearing trees from the order Pinales The wood from conifers (e. g. pine) is called softwood, and the wood from broad-leaved trees (e. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group g. oak) is called hardwood. These names are a bit misleading, as hardwoods are not necessarily hard, and softwoods are not necessarily soft. The well-known balsa (a hardwood) is actually softer than any commercial softwood. Conversely, some softwoods (e. g. yew) are harder than most hardwoods. Taxus baccata is a conifer native to western central and southern Europe, northwest Africa, northern Iran and southwest

Wood products such as plywood are typically classified as engineered wood and not considered raw wood. Plywood is a type of Engineered board made from thin sheets of Wood, called plies or veneers

Color

In species which show a distinct difference between heartwood and sapwood the natural colour of heartwood is usually darker than that of the sapwood, and very frequently the contrast is conspicuous. This is produced by deposits in the heartwood of various materials resulting from the process of growth, increased possibly by oxidation and other chemical changes, which usually have little or no appreciable effect on the mechanical properties of the wood. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Some experiments on very resinous Longleaf Pine specimens, however, indicate an increase in strength. The 'Longleaf Pine' ( Pinus palustris) is a Pine native to the southeast United States, found along the coastal plain from eastern Texas to southeast This is due to the resin which increases the strength when dry. Resin, not to be confused with Rosin, is a Hydrocarbon Secretion of many Plants particularly coniferous trees. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites; however they are very flammable. The termites are a group of Social Insects usually classified at the taxonomic rank of order Isoptera (but see also taxonomy Stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in strength thereby. Spruce refers to Trees of the genus Picea, a genus of about 35 species of Coniferous Evergreen trees in the Family Pinaceae

The wood of Coast Redwood is distinctively red in colour

Since the late wood of a growth ring is usually darker in colour than the early wood, this fact may be used in judging the density, and therefore the hardness and strength of the material. Sequoia sempervirens is the sole living Species of the Genus Sequoia in the cypress family Cupressaceae (formerly This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood not infrequently appear on a finished surface as darker than the denser late wood, though on cross sections of heartwood the reverse is commonly true. Except in the manner just stated the colour of wood is no indication of strength.

Abnormal discolouration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. Tsuga (from ツガ ja 栂 the name for Tsuga sieboldii) is a genus of conifers in the family Pinaceae. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discolouration is merely an indication of an injury, and in all probability does not of itself affect the properties of the wood. Certain rot-producing fungi impart to wood characteristic colours which thus become symptomatic of weakness; however an attractive effect known as spalting produced by this process is often considered a desirable characteristic. A wood-decay fungus is a variety of Fungus which has the ability to digest Wood, causing it to Rot. Spalting is any form of wood coloration caused by Fungi. Although primarily found in dead trees it can also occur under stressed tree conditions or even in living trees Ordinary sap-staining is due to fungous growth, but does not necessarily produce a weakening effect.

Structure

In coniferous or softwood species the wood cells are mostly of one kind, tracheids, and as a result the material is much more uniform in structure than that of most hardwoods. Tracheids are elongated cells in the Xylem of Vascular plants serving in the transport of water and mineral salts There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example. In Vascular plants phloem is the living tissue that carries organic Nutrients (known as photosynthate particularly Sucrose, a sugar to

Magnified cross-section of a diffuse-porous hardwood wood (Black Walnut), showing the vessels, rays (white lines) and annual rings

The structure of the hardwoods is more complex. Juglans nigra, commonly known as black walnut or American walnut, is a tree Species native to eastern North America. ^[3] They are more or less filled with vessels: in some cases (oak, chestnut, ash) quite large and distinct, in others (buckeye, poplar, willow) too small to be seen plainly without a small hand lens. For the South African Thoroughbred racehorse see Horse Chestnut (horse. Populus is a genus of between 25–35 species of Flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. Willows, sallows and osiers form the Genus Salix, around 400 species of Deciduous Trees and Shrubs found primarily In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous. In ring-porous species, such as ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak, the larger vessels or pores (as cross sections of vessels are called) are localized in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. For the historical incident involving a ship of this name see Catalpa rescue. Elms are Deciduous and Semi-deciduous Trees comprising the genus Ulmus, family Ulmaceae, found The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibres. These fibres are the elements which give strength and toughness to wood, while the vessels are a source of weakness.

In diffuse-porous woods the pores are scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are basswood, birch, buckeye, maple, poplar, and willow. Tilia is a Genus of about 30 species of Trees native throughout most of the temperate Northern Hemisphere, in Asia (where the greatest Birch is the name of any Tree of the genus Betula ( Bé-tu-la) in the family Betulaceae, closely related to the Some species, such as walnut and cherry, are on the border between the two classes, forming an intermediate group. Walnuts (genus Juglans) are Plants in the family Juglandaceae. This article is about the Cherry berry also classified as fruit for the ornamental tree See Cherry Blossom.

Black locust end grain, showing the ring-porous structure. Black Locust ( Robinia pseudoacacia) is a Tree in the subfamily Faboideae of the pea family Fabaceae.

If a heavy piece of pine is compared with a light specimen it will be seen at once that the heavier one contains a larger proportion of late wood than the other, and is therefore considerably darker. The late wood of all species is denser than that formed early in the season, hence the greater the proportion of late wood the greater the density and strength. When examined under a microscope the cells of the late wood are seen to be very thick-walled and with very small cavities, while those formed first in the season have thin walls and large cavities. The strength is in the walls, not the cavities. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of early and late wood. The width of ring is not nearly so important as the proportion of the late wood in the ring.

It is not only the proportion of late wood, but also its quality, that counts. In specimens that show a very large proportion of late wood it may be noticeably more porous and weigh considerably less than the late wood in pieces that contain but little. One can judge comparative density, and therefore to some extent weight and strength, by visual inspection.

The twisty branch of a Lilac tree

No satisfactory explanation can as yet be given for the real causes underlying the formation of early and late wood. The unrelated but somewhat similar-looking Chinaberry ( Melia azedarach) is sometimes called "lilac" too Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of the wood formed, though it is not possible to formulate a rule governing it. In general, however, it may be said that where strength or ease of working is essential, woods of moderate to slow growth should be chosen. But in choosing a particular specimen it is not the width of ring, but the proportion and character of the late wood which should govern.

In the case of the ring-porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations.

In ring-porous woods of good growth it is usually the middle portion of the ring in which the thick-walled, strength-giving fibers are most abundant. As the breadth of ring diminishes, this middle portion is reduced so that very slow growth produces comparatively light, porous wood composed of thin-walled vessels and wood parenchyma. In good oak these large vessels of the early wood occupy from 6 to 10 per cent of the volume of the log, while in inferior material they may make up 25 per cent or more. The late wood of good oak, except for radial grayish patches of small pores, is dark colored and firm, and consists of thick-walled fibers which form one-half or more of the wood. Remote Authentication Dial In User Service ( RADIUS) is a networking protocol that provides centralized access authorization and accounting management for people or computers In inferior oak, such fiber areas are much reduced both in quantity and quality. Such variation is very largely the result of rate of growth.

Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in the forest, and in the manufacture of articles where strength is an important consideration such "second-growth" hardwood material is preferred. A forest is an area with a high density of Trees There are many definitions of a forest based on various criteria This is particularly the case in the choice of hickory for handles and spokes. A spoke is one of some number of rods radiating from the center of a Wheel (the hub where the Axle connects connecting the hub with the round traction surface Here not only strength, but toughness and resilience are important. The results of a series of tests on hickory by the U. S. Forest Service show that:

"The work or shock-resisting ability is greatest in wide-ringed wood that has from 5 to 14 rings per inch (rings 1. Inches redirects here To see the Les Savy Fav album see Inches. 8-5 mm thick), is fairly constant from 14 to 38 rings per inch (rings 0. 7-1. 8 mm thick), and decreases rapidly from 38 to 47 rings per inch (rings 0. 5-0. 7 mm thick). The strength at maximum load is not so great with the most rapid-growing wood; it is maximum with from 14 to 20 rings per inch (rings 1. 3-1. 8 mm thick), and again becomes less as the wood becomes more closely ringed. The natural deduction is that wood of first-class mechanical value shows from 5 to 20 rings per inch (rings 1. 3-5 mm thick) and that slower growth yields poorer stock. Thus the inspector or buyer of hickory should discriminate against timber that has more than 20 rings per inch (rings less than 1. 3 mm thick). Exceptions exist, however, in the case of normal growth upon dry situations, in which the slow-growing material may be strong and tough. "^[4]

The effect of rate of growth on the qualities of chestnut wood is summarized by the same authority as follows:

"When the rings are wide, the transition from spring wood to summer wood is gradual, while in the narrow rings the spring wood passes into summer wood abruptly. The width of the spring wood changes but little with the width of the annual ring, so that the narrowing or broadening of the annual ring is always at the expense of the summer wood. The narrow vessels of the summer wood make it richer in wood substance than the spring wood composed of wide vessels. Therefore, rapid-growing specimens with wide rings have more wood substance than slow-growing trees with narrow rings. Since the more the wood substance the greater the weight, and the greater the weight the stronger the wood, chestnuts with wide rings must have stronger wood than chestnuts with narrow rings. This agrees with the accepted view that sprouts (which always have wide rings) yield better and stronger wood than seedling chestnuts, which grow more slowly in diameter. "^[4]

In diffuse-porous woods, as has been stated, the vessels or pores are scattered throughout the ring instead of collected in the early wood. The effect of rate of growth is, therefore, not the same as in the ring-porous woods, approaching more nearly the conditions in the conifers. In general it may be stated that such woods of medium growth afford stronger material than when very rapidly or very slowly grown. In many uses of wood, strength is not the main consideration. If ease of working is prized, wood should be chosen with regard to its uniformity of texture and straightness of grain, which will in most cases occur when there is little contrast between the late wood of one season's growth and the early wood of the next.

Monocot wood

Structural tissue resembling ordinary 'dicot' wood is produced by a number of monocot plants, and these are also usually called wood. Monocotyledons or monocots are one of two major groups of Flowering plants (angiosperms that are traditionally recognised the other being Dicotyledons Of these, the wood of the grass bamboo has considerable economic importance, larger culms being used in the manufacture of engineered flooring, panels and veneer. Bamboo is a group of Woody perennial Evergreen Plants in the True grass family Poaceae, subfamily In Woodworking, veneer refers to thin slices of wood usually thinner than 3 mm (1/8 inch that are typically Glued onto core panels (typically Wood Other plant groups that produce woody tissue are palms, and members of the Liliales, such as Dracaena and Cordyline. Arecaceae or Palmae (also known by the name Palmaceae, which is taxonomically invalid or commonly palm tree) the palm family is a family of Flowering Liliales is an order of Monocotyledonous Flowering plants This order of necessity includes the family Liliaceae, but both the family and the order have Dracaena (romanized form of the Ancient Greek δράκαινα - drakaina "female dragon" is a genus of about 40 species of Cordyline is a Genus of about 15 species of woody Monocotyledonous Flowering plants classified in Asparagaceae or alternatively With all these woods, the structure and composition of the structural tissue is quite different from ordinary wood.

Water content

Water occurs in living wood in three conditions, namely: (1) in the cell walls, (2) in the protoplasmic contents of the cells, and (3) as free water in the cell cavities and spaces. Water is a common Chemical substance that is essential for the survival of all known forms of Life. A cell wall is a tough flexible and sometimes fairly rigid layer surrounding a cell, located external to the Cell membrane, which provides the cell with structural Protoplasm is the living contents of a cell that are surrounded by a Plasma membrane. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried retains from 8-16% of water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry.

The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect of common observation is in the softening action of water on paper or cloth. A textile is a flexible material comprised of a network of natural or artificial Fibres often referred to as thread or Yarn. Within certain limits the greater the water content the greater its softening effect.

Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as that which a green block of the same size will support. Spruce refers to Trees of the genus Picea, a genus of about 35 species of Coniferous Evergreen trees in the Family Pinaceae

The greatest increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected. The yield strength or yield point of a Material is defined in Engineering and Materials science as the stress at which a material An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substance's tendency to be deformed elastically (i

Wood as fuel

Main article: Wood fuel

Wood is burned as a fuel mostly in rural areas of the world. Hard wood is preferred over softwood because it creates less smoke and burns longer. Adding a woodstove or fireplace to a home adds ambiance and warmth. ^[5]

See also

The churches of Kizhi, Russia are among a handful of World Heritage Sites built entirely of wood, without metal joints. Kizhi (Ки́жи Кижи́ Kiži is an Island on Lake Onega in the Republic of Karelia ( Medvezhyegorsky District) Russia with Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending A UNESCO World Heritage Site is a site (such as a Forest, Mountain, Lake, Desert, Monument, Building, complex

• Driftwood
• Dunnage
• Engineered wood
• Forest
• Forestry
• List of woods
• Lumber
• Plywood
• Tinder
• Tree
• Wood as a medium
• Wood drying
• Wood-plastic composite
• Wood warping
• Woodblock graffiti
• Woodworm
• Xylotheque

References

• Hoadley, R. Bruce. (2000) Understanding Wood: A Craftsman’s Guide to Wood Technology. Taunton Press. ISBN 1-56158-358-8
• Shigo, Alex. (1986) A New Tree Biology Dictionary. Shigo and Trees, Associates. ISBN 0-943563-12-7