Hey, Imma let you finish but, Wood From Wikipedia, the free encyclopedia "Wooden" and "Heartwood" redirect here. For other uses, see Wooden (disambiguation) and Heartwood (disambiguation). For small forests, see woodland. For wood as a commodity, see lumber. For other uses, see Wood (disambiguation). Page semi-protected Wood surface, showing several features Wood is a hard, fibrous structural tissue found in the stems and roots of trees and other woody plants. It has been used for thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees,[1] or it is defined more broadly to include the same type of tissue elsewhere such as in tree roots or in other plants such as shrubs.[citation needed] In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also mediates the transfer of water and nutrients to the leaves and other growing tissues. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or wood chips or fiber. The earth contains about one trillion tonnes of wood, which grows at a rate of 10 billion tonnes per year. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as a source of renewable energy. In 1991, approximately 3.5 billion cubic meters of wood were harvested. Dominant uses were for furniture and building construction.[2] Contents [hide] 1 History 2 Physical properties 2.1 Growth rings 2.2 Knots 2.3 Heartwood and sapwood 2.4 Color 2.5 Water content 2.6 Structure 2.6.1 Earlywood and latewood in softwood 2.6.2 Earlywood and latewood in ring-porous woods 2.6.3 Earlywood and latewood in diffuse-porous woods 2.7 Monocot wood 3 Hard and soft woods 4 Chemistry of wood 4.1 Extractives 5 Uses 5.1 Fuel 5.2 Construction 5.3 Furniture and utensils 5.3.1 Engineered wood 5.3.2 Next generation wood products 5.4 In the arts 5.5 Sports and recreational equipment 5.6 Medicine 6 See also 7 References 8 Footnotes History A 2011 discovery in the Canadian province of New Brunswick uncovered the earliest known plants to have grown wood, approximately 395 to 400 million years ago.[3] People have used wood for millennia for many purposes, primarily as a fuel or as a construction material for making houses, tools, weapons, furniture, packaging, artworks, and paper. Wood can be dated by carbon dating and in some species by dendrochronology to make inferences about when a wooden object was created. The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at that time.[4] Physical properties Growth rings Wood, in the strict sense, is yielded by trees, which increase in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. Where there are clear seasons, growth can occur in a discrete annual or seasonal pattern, leading to growth rings; these can usually be most clearly seen on the end of a log, but are also visible on the other surfaces. If these seasons are annual these growth rings are referred to as annual rings. Where there is no seasonal difference growth rings are likely to be indistinct or absent. If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season is then known as the latewood or summerwood.[5] However, there are major differences, depending on the kind of wood (see below). Knots A knot on a tree at the Garden of the Gods public park in Colorado Springs, Colorado (October 2006) A knot is a particular type of imperfection in a piece of wood; it will affect the technical properties of the wood, usually for the worse, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood.