Bark, also known as periderm, is the outermost layer of stems and roots of woody plants such as trees. A stem is one of two main structural axes of a Vascular plant. ROOT is an object-oriented program and library developed by CERN. 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 It overlays the wood and consists of three layers, the cork, the phloem and the vascular cambium. Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs Cork cambium is a tissue found in many vascular plants as part of the Periderm. In Vascular plants phloem is the living tissue that carries organic Nutrients (known as photosynthate particularly Sucrose, a sugar to The vascular cambium is a Lateral meristem in the Vascular tissue of plants Products used by people that are derived from bark include: spices and other flavorings, tannin, resin, latex, medicines, poisons, various hallucinatory chemicals and cork. A spice is a dried Seed, Fruit, Root, Bark or vegetative substance used in Nutritionally insignificant quantities as a Food additive LaTeX (ˈleɪtɛ Bark has been used to make cloths, canoes, ropes and used as a surface for paintings and map making;[1] A number of plants are also grown for their attractive or interesting bark colorations and surface textures. [2][3]
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Botanic description
- Cork - an external, secondary tissue impermeable to water and gases.
- Cork cambium - A layer of cells, normally one or two cell layers thick that is in a persistent meristematic state that produces cork. 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 A meristem is a tissue in all Plants consisting of undifferentiated cells ( meristematic cells) and found in zones of the plant where growth can take place
- Phelloderm - (not always present) A layer of cells formed in some plants from the inner cells of the cork cambium (Cork is produced from the outer layer).
- Cortex - The primary tissue of stems and roots. A stem is one of two main structural axes of a Vascular plant. In stems the cortex is between the epidermis layer and the phloem, in roots the inner layer is not phloem but the pericycle. The pericycle is a cylinder of parenchyma cells that lies just inside the Endodermis and is the outer most part of the Stele (biology of plants
- Phloem - nutrient conducting tissue composed of sieve tube or sieve cells mixed with parenchyma and fibers. A nutrient is food or chemicals that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment Parenchyma is a term used to describe a bulk of a substance It is used in different ways in Animals and in Plants.
In old stems the epidermal layer, cortex, and primary phloem become separated from the inner tissues by thicker formations of cork. Due to the thickening cork layer these cells die because they do not receive water and nutrients. This dead layer is the rough corky bark that forms around tree trunks and other stems. In smaller stems and on typically non woody plants, sometimes a secondary covering forms called the periderm, which is made up of cork cambian, cork and phelloderm. 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 It replaces the dermal layer and acts as a covering much like the corky bark, it too is made up of mostly dead tissue. The skin on the potato is a periderm.
Definitions of the term can vary. In another usage, bark consists of the dead and protective tissue found on the outside of a woody stem, and does not include the vascular tissue.
The vascular cambium is the only part of a woody stem where cell division occurs. This is an article about vascular tissue in plants For transport in animals see Circulatory system. Cell division is a process by which a cell, called the parent cell divides into two or more cells called daughter cells. It contains undifferentiated cells that divide rapidly to produce secondary xylem to the inside and secondary phloem to the outside. In Vascular plants xylem is one of the two types of transport tissue Phloem being the other In Vascular plants phloem is the living tissue that carries organic Nutrients (known as photosynthate particularly Sucrose, a sugar to
Along with the xylem, the phloem is one of the two tissues inside a plant that are involved with fluid transport. In Vascular plants xylem is one of the two types of transport tissue Phloem being the other The phloem transports organic molecules (particularly sugars) to wherever they are needed. Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose.
Uses
Cork, sometimes confused with bark in colloquial speech, is the outermost layer of a woody stem, derived from the cork cambium. Cork cambium is a tissue found in many vascular plants as part of the Periderm. It serves as protection against damage, parasites and diseases, as well as dehydration and extreme temperatures. Parasitism is a type of symbiotic relationship between Organisms of different Species. A disease is an abnormal condition of an organism that impairs bodily functions and can be deadly Cork can contain antiseptics like tannins. Antiseptics (from Greek αντί - anti, '"against" + σηπτικός - septikos, "putrefactive" are antimicrobial Tannins are Astringent, bitter plant Polyphenols that either bind and Precipitate or shrink Proteins The astringency from the tannins is what Some cork is substantially thicker, providing further insulation and giving the bark a characteristic structure, in some cases thick enough to be harvestable as cork product without killing the tree. Cork material is a Prime-subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree Quercus Bark has been used a covering in the making of canoes, the most famous example of this is the birch canoes of North America. [4]
The bark of some trees is edible.
Among the commercial products made from bark are cork, cinnamon, quinine[5] (from the bark of Cinchona)[6] and aspirin (from the bark of willow trees). Cork material is a Prime-subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree Quercus Cinnamon ( Cinnamomum verum, synonym C zeylanicum) is a small Evergreen Tree 10–15 metres (32 Quinine (ˈkwaɪnaɪn kwɪˈniːn ˈkwiːniːn is a natural white Crystalline Alkaloid having Antipyretic (fever-reducing antimalarial, Cinchona is a Genus of about 25 Species in the family Rubiaceae, native to tropical South America. Aspirin, or acetylsalicylic acid (ASA (əˌsɛtɨlsælɨˌsɪlɨk ˈæsɨd is a Salicylate drug, often used as an Analgesic to relieve Willows, sallows and osiers form the Genus Salix, around 400 species of Deciduous Trees and Shrubs found primarily The bark of some trees notably oak (Quercus robur) is a source of tannic acid, which is used in tanning. Tanning is the process of converting Putrescible skin into non-putrescible Leather, usually with Tannin, an Acidic Chemical compound Bark chips generated as a by-product of lumber production, are often used in bark mulch in western North America. A by-product is a secondary or incidental product deriving from a Manufacturing process a Chemical reaction or a biochemical pathway and is not the primary product Lumber or timber is Wood in any of its stages from felling through readiness for use as structural Material for Construction, or In Agriculture and Gardening, '''mulch''' is a protective cover placed over the Soil, primarily to modify the effects of the local Climate. Bark is important to the horticultural industry since in shredded form it is used for plants that do not thrive in ordinary soil, such as epiphytes. An epiphyte is an organism that grows upon or attaches to a living plant
Wood Adhesives from Bark-Derived Phenols: Wood Bark has lignin content and when it is pyrolyzed (subjected to high temperatures in the absence of oxygen), it yields a liquid bio-oil product rich in natural phenol derivatives. Lignin or lignen is a complex Chemical compound most commonly derived from Wood and an integral part of the secondary Cell walls of Plants Pyrolysis is the Chemical decomposition of organic materials by heating in the absence of Oxygen or any other reagents except possibly Steam The phenol derivatives are isolated and recovered for application as a replacement for fossil-based phenols in phenol-formaldehyde (PF) resins used in Oriented Strand Board (OSB) and plywood. In Organic chemistry, phenols, sometimes called phenolics, are a class of Chemical compounds consisting of a Hydroxyl group (- Oriented strand board, or OSB, or waferboard or Sterling board (UK is an Engineered wood product formed by layering strands (flakes of
Bark removal
Cut logs used for the production of lumber or even log cabins generally have the bark removed, either just before cutting or for curing. Lumber or timber is Wood in any of its stages from felling through readiness for use as structural Material for Construction, or Such logs and even trunks and branches found in their natural state of decay in forests, where the bark has fallen off, are said to be decorticated.
A number of living organisms live in or on bark, including insects,[7] fungi and other plants like mosses , algae and other vascular plants. Many of these organisms are pathogens or parasites but some also have symbiotic relationships.
Bark repair
The degree to which trees are able to repair gross physical damage to their bark is very variable. Some are able to produce a callus growth which heals over the wound rapidly, but leaves a clear scar, whilst others such as oaks do not produce an extensive callus repair.
Gallery
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See also
References
- ^ Taylor, Luke. Bark painting is an Australian Aboriginal art-form which is done on the interior strip of a tree bark. A bark beetle is one of approximately 220 Genera with 6000 Species of Beetles in the Subfamily Scolytinae. In Botany, trunk (or bole) refers to the main structural member of a Tree that supports the Branches and is supported by and directly attached 1996. Seeing the inside bark painting in western Arnhem Land. Oxford studies in social and cultural anthropology. Oxford: Clarendon Press.
- ^ Sandved, Kjell Bloch, Ghillean T. Prance, and Anne E. Prance. 1993. Bark the formation, characteristics, and uses of bark around the world. Portland, Or: Timber Press.
- ^ Vaucher, Hugues, and James E. Eckenwalder. 2003. Tree bark a color guide. Portland: Timber
- ^ Adney, Tappan, and Howard Irving Chapelle. 1964. The bark canoes and skin boats of North America. Washington: Smithsonian Institution.
- ^ Duran-Reynals, Marie Louise de Ayala. 1946. The fever bark tree; the pageant of quinine. Garden City, N. Y. : Doubleday.
- ^ Markham, Clements R. 1880. Peruvian bark. A popular account of the introduction of chinchona cultivation into British India. London: J. Murray.
- ^ Lieutier, François. 2004. Bark and wood boring insects in living trees in Europe a synthesis. Dordrecht: Kluwer Academic Publishers.
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