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Root Pressure
Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the daytime. When transpiration is high, xylem sap is usually under tension, rather than under pressure, due to transpirational pull. At night in some plants, root pressure causes guttation or exudation of drops of xylem sap from the tips or edges of leaves. Root pressure is studied by removing the shoot of a plant near the soil level. Xylem sap will exude from the cut stem for hours or days due to root pressure. If a pressure gauge is attached to the cut stem, the root pressure can be measured. Root pressure is caused by active distribution of mineral nutrient ions into the root xylem. Without transpiration to carry the ions up the stem, they accumulate in the root xylem and lower the water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary And Secondary Cotton Roots
Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ''Primary'' (album) by Rubicon (2002) * "Primary" (song) by The Cure * "Primary", song by Spoon from the album '' Telephono'' Other uses in arts, entertainment, and media * Primaries or primary beams, in E. E. Smith's science-fiction series '' Lensman'' * ''Primary'' (film), American political documentary (1960) Computing * PRIMARY, an X Window selection * Primary data storage, computer technology used to retain digital data * Primary server, main server on the server farm Education * Primary education, the first stage of compulsory education * Primary FRCA, academic examination for anaesthetists in the U.K. * Primary school, school providing primary education Mathematics * ''p''-group of prime power order * Primary decom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cortex (botany)
In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. The outer cortical cells often acquire irregularly thickened cell walls, and are called collenchyma cells. Plants Stems and branches In the three dimensional structure of herbaceous stems, the epidermis, cortex and vascular cambium form concentric cylinders around the inner cylindrical core of pith. Some of the outer cortical cells may contain chloroplasts, giving them a green color. They can therefore produce simple carbohydrates through photosynthesis. In woody plants, the cortex is located between the periderm (bark) and the vascular tissue ( phloem, in particular). It is responsible for the transportation of materials into the central cylinder of the root through diffusion and ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maple
''Acer'' is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http://www.mobot.org/MOBOT/research/APweb/. There are approximately 132 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, '' Acer laurinum'', extends to the Southern Hemisphere.Gibbs, D. & Chen, Y. (2009The Red List of Maples Botanic Gardens Conservation International (BGCI) The type species of the genus is the sycamore maple ''Acer pseudoplatanus'', one of the most common maple species in Europe.van Gelderen, C. J. & van Gelderen, D. M. (1999). '' Maples for Gardens: A Color Encyclopedia'' Most maples usually have easily identifiable palmate leaves (with a few exceptions, such as '' Acer carpinifolium'', '' Acer laurinum'', and '' Acer negundo'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugar Maple
''Acer saccharum'', the sugar maple, is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is native to the hardwood forests of eastern Canada and the eastern United States. Sugar maple is best known for being the primary source of maple syrup and for its brightly colored fall foliage. It may also be called "rock maple," "sugar tree," "sweet maple," or, particularly in reference to the wood, "hard maple," " birds-eye maple," or "curly maple," the last two being specially figured lumber. Description ''Acer saccharum'' is a deciduous tree normally reaching heights of , and exceptionally up to . A 10-year-old tree is typically about tall. As with most trees, forest-grown sugar maples form a much taller trunk and narrower canopy than open-growth ones. The leaves are deciduous, up to long and wide, palmate, with five lobes and borne in opposite pairs. The basal lobes are relatively small, while the upper lobes are larger and deeply notched. In con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pascal (unit)
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m2). It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar, and the kilopascal (1 kPa = 1000 Pa), which is equal to one centibar. The unit of measurement called '' standard atmosphere (atm)'' is defined as . Meteorological observations typically report atmospheric pressure in hectopascals per the recommendation of the World Meteorological Organization, thus a standard atmosphere (atm) or typical sea-level air pressure is about 1013 hPa. Reports in the United States typically use inches of mercury or millibars (hectopascals). In Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmodesmata
Plasmodesmata (singular: plasmodesma) are microscopic channels which traverse the cell walls of plant cells and some algal cells, enabling transport and communication between them. Plasmodesmata evolved independently in several lineages, and species that have these structures include members of the Charophyceae, Charales, Coleochaetales and Phaeophyceae (which are all algae), as well as all embryophytes, better known as land plants. Unlike animal cells, almost every plant cell is surrounded by a polysaccharide cell wall. Neighbouring plant cells are therefore separated by a pair of cell walls and the intervening middle lamella, forming an extracellular domain known as the apoplast. Although cell walls are permeable to small soluble proteins and other solutes, plasmodesmata enable direct, regulated, symplastic transport of substances between cells. There are two forms of plasmodesmata: primary plasmodesmata, which are formed during cell division, and secondary plasmodesma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Transport
In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport, which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area of low concentration, with energy. Active transport is essential for various physiological processes, such as nutrient uptake, hormone secretion, and nig impulse transmission. For example, the sodium-potassium pump uses ATP to pump sodium ions out of the cell and potassium ions into the cell, maintaining a concentration gradient essential for cellular function. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoplast Pathway
The ''apoplast '' is the extracellular space outside of plant cell membranes, especially the fluid-filled cell walls of adjacent cells where water and dissolved material can flow and diffuse freely. Fluid and material flows occurring in any extracellular space are called ''apoplastic'' flow or apoplastic transport. The apoplastic pathway is one route by which water and solutes are transported and distributed to different places through tissues and organs, contrasting with the symplastic pathway. To prevent uncontrolled leakage to unwanted places, in certain areas there are barriers to the apoplastic flow: in roots the Casparian strip has this function Outside the plant epidermis of aerial plant parts is a protective waxy film called plant cuticle that protects against drying out, but also waterproofs the plant against external water. The apoplast is important for all the plant's interaction with its environment: The main carbon source (carbon dioxide) needs to be solubilize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suberin
Suberin is a lipophilic, complex polyester biopolymer found in plants. It is composed of long-chain fatty acids (called suberin acids) and glycerol. Suberin is interconnected with cutin and lignin and forms a protective barrier in the epidermal and peridermal cell walls of higher plants. Suberin and lignin are considered covalently linked to lipids and carbohydrates, respectively. Lignin is again covalently linked to suberin, and to a lesser extent to cutin, thus construdting a complex macromolecular matrix. Suberin is a major constituent of cork, and is named after the cork oak, '' Quercus suber''. Its main function is as a barrier to movement of water and solutes. Anatomy and physiology Suberin is highly hydrophobic and a somewhat 'rubbery' material. In roots, suberin is deposited in the radial and transverse/tangential cell walls of the endodermal cells. This structure, known as the Casparian strip or Casparian band, functions to prevent water and nutrients taken up by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Casparian Strip
The Casparian strip is a band-like thickening in the center of the root endodermis (radial and tangential walls of endodermal cells) of vascular plants (Pteridophytes and Spermatophytes). The composition of the region is mainly suberin, lignin and some structural proteins, which are capable of reducing the diffusive apoplastic flow of water and solutes into the stele, its width varies between species. In the root, the Casparian strip is embedded within the cell wall of endodermal cells in the non-growing region of the root behind the root tip.Taiz, L., Zeiger, Eduardo, Møller, Ian Max, & Murphy, Angus. (2015). Plant physiology and development (Sixth ed.). Here, the Casparian strip serves as a boundary layer separating the apoplast of the cortex from the apoplast of the vascular tissue thereby blocking diffusion of material between the two. This separation forces water and solutes to pass through the plasma membrane via a symplastic route in order to cross the endodermis layer. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pericycle
The pericycle is a cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants. Although it is composed of non-vascular parenchyma cells, it is still considered part of the vascular cylinder because it arises from the procambium as do the vascular tissues it surrounds. In eudicots, it also has the capacity to produce lateral roots. Branch roots arise from this primary meristem tissue. In plants undergoing secondary growth, the pericycle contributes to the vascular cambium often diverging into a cork cambium. In angiosperms certain molecules within the endodermis and the surrounding vasculature are sent to the pericycle which promotes the growth of the root meristems. Location The pericycle is located between the endodermis and phloem in plant roots. In dicot stems, it is situated around the ring of vascular bundles in the stele. Function In dicot roots, the pericycle strengthens the roots and provide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endodermis
The endodermis is the innermost layer of cortex in land plants. It is a cylinder of compact living cells, the radial walls of which are impregnated with hydrophobic substances ( Casparian strip) to restrict apoplastic flow of water to the inside. The endodermis is the boundary between the cortex and the stele. In many seedless plants, such as ferns, the endodermis is a distinct layer of cells immediately outside the vascular cylinder (stele) in roots and shoots. In most seed plants, especially woody types, the endodermis is present in roots but not in stems. The endodermis helps regulate the movement of water, ions and hormones into and out of the vascular system. It may also store starch, be involved in perception of gravity and protect the plant against toxins moving into the vascular system. Structure The endodermis is developmentally the innermost portion of the cortex. It may consist of a single layer of barrel-shaped cells without any intercellular spaces or sometimes s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
