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ROOT

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{{otheruses}} Image:ROOTS1web.jpg thumb|right|250px|Primary and secondary roots in a cotton plant In vascular plants, the '''root''' is that organ of a plant body that typically lies below the surface of the soil (compare with plant stem stem). However, this is not always the case, since a root can also be aerial_root '''aerial''' (that is, growing above the ground) or '''aerating''' (that is, growing up above the ground or especially above water). On the other hand, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is better to define ''root'' as a part of a plant body that bears no leaves, and therefore also lacks Node (botany) nodes. There are also important internal structural differences between stems and roots. The two major functions of roots are 1) absorption of water and inorganic nutrients and 2) anchoring the plant body to the ground.

Root structure
Image:Roots.JPG Hydroponics thumb|Roots of a [[Hydroponics|hydroponically grown plant.html" title="Meaning of hydroponically.html" title="Meaning of thumb|Roots of a [[Hydroponics|hydroponically">thumb|Roots of a [[Hydroponics|hydroponically grown plant">hydroponically.html" title="Meaning of thumb|Roots of a [[Hydroponics|hydroponically">thumb|Roots of a [[Hydroponics|hydroponically grown plant At the tip of every growing root is a conical covering of tissue called the '''root cap'''. It usually is not visible to the naked eye. It consists of undifferentiated soft tissue (parenchyma) with unthickened walls covering the '''Meristem apical meristem'''. The root cap provides mechanical protection to the meristem cells as the root advances through the soil, its cells worn away but quickly replaced by new cells generated by cell division within the meristem. The root cap is also involved in the production of '''mucigel''', a sticky mucilage that coats the new formed cells. These cells contain '''statoliths''', starch grains that move in response to gravity and thus control root orientation. The outside surface of a root is the epidermis (botany) epidermis. Recently produced ''epidermal'' cells absorb water from the surrounding environment and produce outgrowths called '''trichome#root hairs root hairs''' that greatly increase the cell's absorptive surface. Root-hairs are very delicate and generally short-lived, remaining functional for only a few days. However, as the root grows, new epidermal cells emerge and these form new root hairs, replacing those that die. The process by which water is absorbed into the epidermal cells from the soil is known as '''''osmosis'''''. For this reason, water that is salinity saline is more difficult for most plant species to absorb. Image:Root(cross section).jpg dicotyledon.html" title="Meaning of thumb thumb|left|325px|Cross section of the root of a [[dicotyledon.html" title="Meaning of left|325px|Cross section of the root of a [[dicotyledon">thumb|left|325px|Cross section of the root of a [[dicotyledon">left|325px|Cross section of the root of a [[dicotyledon">thumb|left|325px|Cross section of the root of a [[dicotyledon Beneath the epidermis is the '''cortex''', which comprises the bulk of the root. Its main function is storage of starch. Intercellular spaces in the cortex aerate cells for cellular respiration respiration. An '''endodermis''' is a thin layer of small cells forming the innermost part of the cortex and surrounding the vascular tissues deeper in the root. The tightly packed cells of the endodermis contain a substance known as suberin and create an impermeable barrier of sorts. Water can only flow in one direction through the endodermis: in towards the center of the root, rather than outward from the Stele (biology) stele to the cortex. The vascular cylinder, or stele, consists of the cells inside the endodermis. The outer part, known as the '''pericycle''', surrounds the actual vascular tissue. In monocotyledonous plants, the xylem and phloem cells are arranged in a circle around a pith or center, whereas in dicotyledons, the xylem cells form a central "hub" with lobes, and phloem cells fill in the spaces between the lobes.

Root growth
Image:Root-system.web.jpg prairie.html" title="Meaning of thumb thumb|right|350px|Root systems of [[prairie plants.html" title="Meaning of right|350px|Root systems of [[prairie">thumb|right|350px|Root systems of [[prairie plants">right|350px|Root systems of [[prairie">thumb|right|350px|Root systems of [[prairie plants Early root growth is a function of the '''apical meristem''' located near the tip of the root. The meristem cells more or less continuously divide, producing more meristem, root cap cells (these sacrificed to protect the meristem), and undifferentiated root cells. The latter will become the primary tissues of the root, first undergoing elongation, a process that pushes the root tip forward in the growing medium. Gradually these cells differentiate and mature into specialized cells of the root tissues. Roots will generally grow in any direction where the correct environment of Earth's atmosphere air, nutrients and water exists to meet the plant's needs. Roots will not grow in dry soil. Over time, given the right conditions, roots can crack foundations, snap water lines, and lift sidewalks. At germination, roots grow downward due to gravitropism, the growth mechanism of plants that also causes the shoot to grow upward. In some plants (such as ivy), the "root" actually clings to walls and structures; this is known as thigmotropism, or response to touch. Most plants experience growth only along the apical meristems; this is known as '''primary growth''', which encompasses all vertical growth. On the other hand, '''secondary growth''' encompasses all lateral growth, a major component of woody plant tissues. Secondary growth occurs at the lateral meristems, namely the vascular cambium and cork cambium. The former forms secondary xylem and secondary phloem, while the latter forms the periderm, found only in woody plants. In woody plants, the vascular cambium, originating between the xylem and the phloem, forms a cylinder (geometry) cylinder of tissue along the Plant stem stem and root. The cambium layer forms new cells on both the inside and outside of the cambium cylinder, with those on the inside forming secondary xylem cells, and those on the outside forming secondary phloem cells. As secondary xylem accumulates, the "girth" (lateral dimensions) of the stem and root increases. As a result, tissues beyond the secondary phloem (including the epidermis and cortex, in many cases) tend to be pushed outward and are eventually "sloughed off" (shed). At this point, the cork cambium (noting that this process only occurs in woody plants) begins to form the periderm, consisting of protective cork (material) cork cells containing suberin. In roots, the cork cambium originates in the pericycle, a component of the vascular cylinder. Image:Air roots in the Amazon.jpg Amazon Rainforest.html" title="Meaning of 250px 250px|thumb|Stilt roots in the [[Amazon Rainforest support a tree in very soft, wet soil conditions.html" title="Meaning of thumb|Stilt roots in the [[Amazon Rainforest">250px|thumb|Stilt roots in the [[Amazon Rainforest support a tree in very soft, wet soil conditions">thumb|Stilt roots in the [[Amazon Rainforest">250px|thumb|Stilt roots in the [[Amazon Rainforest support a tree in very soft, wet soil conditions The vascular cambium produces new layers of secondary xylem annually. This dead tissue is responsible for most water transport through the vascular tissue (systems and roots).

Types of roots
A true root system consists of a '''primary root''' and '''secondary roots''' (or lateral roots). The primary root originates in the radicle of the seedling. During its growth it rebranches to form the lateral roots. Generally, two categories are recognized: *the taproot: the primary root is prominent and has a single, dominant axis; there are fibrous secondary roots running outward. Usually allows for deeper roots capable of reaching low water tables. Most common in dicots * the primary root is not dominant: the whole root system is fibrous and branches in all directions. Most common in monocots. '''Adventitous roots''' arise from the stem and not from another root. They usually occur in monocots and pteridophytes, but also in a few dicots, such as strawberry (''Fragaria vesca'') and white clover (''Trifolium repens'').

Specialized roots
Image:Mangroves.jpg mangrove.html" title="Meaning of thumb thumb|250px|right|Aerating roots of a [[mangrove.html" title="Meaning of 250px|right|Aerating roots of a [[mangrove">thumb|250px|right|Aerating roots of a [[mangrove">250px|right|Aerating roots of a [[mangrove">thumb|250px|right|Aerating roots of a [[mangrove The roots, or parts of roots, of many plant species have become specialized to serve adaptive purposes besides the two primary functions described in the introduction. * '''Aerating roots''' (or '''pneumatophores'''): roots rising above the ground, especially above water such as in some mangrove genera (Avicennia, Sonneratia) * '''Aerial roots''': roots entirely above the ground, such as in ivy (''Hedera helix'') or in epiphyte epiphytic orchids. They function as prop roots or anchor roots. * '''Contractile roots''': they pull bulbs or corms of monocots deeper in the soil through expanding radially and contracting longitudinally. They show a wrinkled surface. * '''Haustorial roots''': roots of parasitic plants that can absorb water and nutrients from another plant, such as in mistletoe (Viscum album) and Rafflesia. * '''Proteoid roots''' or cluster roots: dense clusters of rootlets of limited growth that develop under low phosphate or low iron conditions in Proteaceae and some plants from the following families Betulaceae, Casuarinaceae, Eleagnaceae, Moraceae, Fabaceae and Myricaceae. * '''Stilt roots''': these are adventitious support roots, common among mangroves. They grow down from lateral branches, branching in the soil. * '''Storage roots''': these roots are modified for storage of nutrients, such as carrots and beets * '''Tubiferous roots''': A portion of a root forms into a roundish knob called a (tuber) for food.

Rooting depths
The distribution of vascular plant roots within the soil depends on plant life form, and the spatial and temporal availability of water and nutrients in the soil. The deepest roots are generally found in deserts and temperate coniferous forests; the shallowest in tundra, boreal forest and temperate grasslands. The deepest observed living root, at least 60 m below the ground surface, was observed during the excavation of an open-pit mine in Arizona, USA.

See also
* Rhizophilous - organisms which thrive in a proximity or in a symbiotic relationship with plant roots. * Mycorrhiza - root symbiosis in which individual hyphae extending from the mycelium of a fungus colonize the roots of a host plant. * fibrous root system * stolon

References
* Brundrett, M. C. 2002. Coevolution of roots and mycorrhizas of land plants. ''New phytologist'' '''154'''(2): 275-304. (Available online: [http://dx.doi.org/10.1046/j.1469-8137.2002.00397.x DOI] | [http://www.blackwell-synergy.com/links/doi/10.1046/j.1469-8137.2002.00397.x/abs/ Abstract] | [http://www.blackwell-synergy.com/links/doi/10.1046/j.1469-8137.2002.00397.x/full/ Full text (HTML)] | [http://www.newphytologist.org/Brundrett.pdf Full text (PDF)]) * Chen, R., E. Rosen, P. H. Masson. 1999. Gravitropism in Higher Plants. ''Plant Physiology'' '''120''' (2): 343-350. (Available online: [http://www.plantphysiol.org/cgi/content/full/120/2/343 Full text (HTML)] | [http://www.plantphysiol.org/cgi/reprint/120/2/343.pdf Full text (PDF)]) - article about how the roots sense gravity. * Clark, Lynn. 2004. ''[http://www.eeob.iastate.edu/classes/bot404/docs/404root104.pdf Primary Root Structure and Development]'' - lecture notes * Raven, J. A., D. Edwards. 2001. Roots: evolutionary origins and biogeochemical significance. ''Journal of Experimental Botany'' '''52 (Suppl 1)''': 381-401. (Available online: [http://jxb.oupjournals.org/cgi/content/abstract/52/suppl_1/381 Abstract] | [http://jxb.oupjournals.org/cgi/content/full/52/suppl_1/381 Full text (HTML)] | [http://jxb.oupjournals.org/cgi/reprint/52/suppl_1/381.pdf Full text (PDF)]) * Schenk, H.J., and R.B. Jackson. 2002. The global biogeography of roots. ''Ecological Monographs'' '''72''' (3): 311-328. * Phillips, W.S. 1963. Depth of roots in soil. ''Ecology'' '''44''' (2): 424.

External links

- Introduction to Botany - University of Arkansas Category:Plant physiology Category:Plant anatomy Category:Plant morphology bg:Корен (ботаника) cs:Kořen de:Wurzel (Pflanze) es:Raíz (botánica) eo:Radiko fr:Racine (botanique) it:Radice (botanica) he:שורש (בוטניקה) lt:Šaknis mk:Корен ms:Akar nl:Wortel (plant) ja:根 pl:Korzeń pt:Raiz simple:Root sk:Koreň (botanika) sv:Rot tr:Kök zh:根 sr:корен :''For other uses of "root", see root (disambiguation).'' '''ROOT''' is a powerful Object oriented programming object oriented data analysis Software package package developed by CERN to replace earlier packages (which include Physics Analysis Workstation PAW, CERNLIB). It was initiated by René Brun and Fons Rademakers in 1994. ROOT is written in C++, and published under the LGPL. It provides platform independent access to a computer's graphics subsystem and Operating System using Abstraction (computer science) abstract layers. Part of the abstract platform are a graphical user interface, container classes, Reflection (computer science) reflection, a C++ Scripting language script and command line Interpreter (computing) interpreter (CINT), and object serialization and persistence. Image:2D_ROI.jpg thumb|320px|right|Example ROOT plot showing regions of interest in a 2D distribution The packages provided by ROOT include those for * ''histogramming'' and ''Graph of a function graphing'' to visualize and analyze Distribution (mathematics) distributions and functions, * ''curve fitting'' (regression analysis) and minimization of functional (mathematics) functionals, * ''statistics tools'' used for data analysis, * ''matrix (mathematics) matrix algebra'', * ''four-vector computations'', as used in high energy physics, * standard ''Function (mathematics) mathematical functions'', * ''multivariate data analysis'', e.g. using Neural Networks, * ''image manipulation'', used e.g. to analyze astronomical pictures, * access to ''distributed data'' (in the context of the Grid computing Grid), * ''distributed computing'', to parallelize Data analysis data analyses, * ''persistence and serialization of objects'', which can cope with changes in class definitions of persistent data, * ''access to databases'', * 3D computer graphics 3D Visualization (graphic) visualizations (geometry) * creating files in various ''graphics formats'', like PostScript, JPEG, SVG, * interfacing Python programming language Python and Ruby programming language Ruby code in both directions, * interfacing Monte Carlo method Monte Carlo event generators. A key feature of ROOT is a data container called ''tree'', with its substructures ''branches'' and ''leaves''. A tree can be seen as a sliding window to the raw data, as stored in a file. Data from the next entry in the file can be retrieved by advancing the index in the tree. This avoids memory allocation issues associated with object creation, and allows the tree to act as a lightweight container while handling buffering invisibly. ROOT's focus on performance is caused by the amount of data that the Large Hadron Collider's experiments will collect, estimated to several petabytes per year. Physicists are expected to analyze this data using ROOT. ROOT is currently mainly used in data analysis and data acquisition in high energy physics experiments - most of their plots and results are obtained using ROOT.

See also
* CERN * Physics Analysis Workstation PAW * IGOR Pro * Scientific computing

External link

- The ROOT System Home Page Category:Experimental particle physics Category:Numerical software Category:Statistical software Category:Data management it:ROOT (programma) tr:ROOT

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