title: Chemical reaction

text: From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, and Isaac Newton tried to establish theories of experimentally observed chemical transformations. The phlogiston theory was proposed in 1667 by Johann Joachim Becher. It postulated the existence of a fire-like element called "phlogiston", which was contained within combustible bodies and released during combustion. This proved to be false in 1785 by Antoine Lavoisier who found the correct explanation of the combustion as a reaction with oxygen from the air.


title: Chemical reaction

text: Joseph Louis Gay-Lussac recognized in 1808 that gases always react in a certain relationship with each other. Based on this idea and the atomic theory of John Dalton, Joseph Proust had developed the law of definite proportions, which later resulted in the concepts of stoichiometry and chemical equations.


title: Chemical reaction

text: Regarding the organic chemistry, it was long believed that compounds obtained from living organisms were too complex to be obtained synthetically. According to the concept of vitalism, organic matter was endowed with a "vital force" and distinguished from inorganic materials. This separation was ended however by the synthesis of urea from inorganic precursors by Friedrich Wöhler in 1828. Other chemists who brought major contributions to organic chemistry include Alexander William Williamson with his synthesis of ethers and Christopher Kelk Ingold, who, among many discoveries, established the mechanisms of substitution reactions.


title: Chemical reaction

text: Chemical equations are used to graphically illustrate chemical reactions. They consist of chemical or structural formulas of the reactants on the left and those of the products on the right. They are separated by an arrow (→) which indicates the direction and type of the reaction; the arrow is read as the word "yields". The tip of the arrow points in the direction in which the reaction proceeds. A double arrow () pointing in opposite directions is used for equilibrium reactions. Equations should be balanced according to the stoichiometry, the number of atoms of each species should be the same on both sides of the equation. This is achieved by scaling the number of involved molecules (A, B, C and D in a schematic example below) by the appropriate integers "a, b, c" and "d".


title: Chemical reaction

text: More elaborate reactions are represented by reaction schemes, which in addition to starting materials and products show important intermediates or transition states. Also, some relatively minor additions to the reaction can be indicated above the reaction arrow; examples of such additions are water, heat, illumination, a catalyst, etc. Similarly, some minor products can be placed below the arrow, often with a minus sign.


title: Chemical reaction

text: Retrosynthetic analysis can be applied to design a complex synthesis reaction. Here the analysis starts from the products, for example by splitting selected chemical bonds, to arrive at plausible initial reagents. A special arrow (⇒) is used in retro reactions.


title: Chemical reaction

text: The elementary reaction is the smallest division into which a chemical reaction can be decomposed, it has no intermediate products. Most experimentally observed reactions are built up from many elementary reactions that occur in parallel or sequentially. The actual sequence of the individual elementary reactions is known as reaction mechanism. An elementary reaction involves a few molecules, usually one or two, because of the low probability for several molecules to meet at a certain time.


title: Chemical reaction

text: The most important elementary reactions are unimolecular and bimolecular reactions. Only one molecule is involved in a unimolecular reaction; it is transformed by isomerization or a dissociation into one or more other molecules. Such reactions require the addition of energy in the form of heat or light. A typical example of a unimolecular reaction is the cis–trans isomerization, in which the cis-form of a compound converts to the trans-form or vice versa.


title: Chemical reaction

text: In a typical dissociation reaction, a bond in a molecule splits (ruptures) resulting in two molecular fragments. The splitting can be homolytic or heterolytic. In the first case, the bond is divided so that each product retains an electron and becomes a neutral radical. In the second case, both electrons of the chemical bond remain with one of the products, resulting in charged ions. Dissociation plays an important role in triggering chain reactions, such as hydrogen–oxygen or polymerization reactions.


title: Chemical reaction

text: For bimolecular reactions, two molecules collide and react with each other. Their merger is called chemical synthesis or an addition reaction.


title: Chemical reaction

text: Another possibility is that only a portion of one molecule is transferred to the other molecule. This type of reaction occurs, for example, in redox and acid-base reactions. In redox reactions, the transferred particle is an electron, whereas in acid-base reactions it is a proton. This type of reaction is also called metathesis.


title: Chemical reaction

text: Most chemical reactions are reversible; that is, they can and do run in both directions. The forward and reverse reactions are competing with each other and differ in reaction rates. These rates depend on the concentration and therefore change with the time of the reaction: the reverse rate gradually increases and becomes equal to the rate of the forward reaction, establishing the so-called chemical equilibrium. The time to reach equilibrium depends on parameters such as temperature, pressure, and the materials involved, and is determined by the minimum free energy. In equilibrium, the Gibbs free energy must be zero. The pressure dependence can be explained with the Le Chatelier's principle. For example, an increase in pressure due to decreasing volume causes the reaction to shift to the side with fewer moles of gas.


title: Chemical reaction

text: The reaction yield stabilizes at equilibrium but can be increased by removing the product from the reaction mixture or changed by increasing the temperature or pressure. A change in the concentrations of the reactants does not affect the equilibrium constant but does affect the equilibrium position.


title: Chemical reaction

text: Chemical reactions are determined by the laws of thermodynamics. Reactions can proceed by themselves if they are exergonic, that is if they release free energy. The associated free energy change of the reaction is composed of the changes of two different thermodynamic quantities, enthalpy and entropy:


title: Chemical reaction

text: Reactions can be exothermic, where Δ"H" is negative and energy is released. Typical examples of exothermic reactions are combustion, precipitation and crystallization, in which ordered solids are formed from disordered gaseous or liquid phases. In contrast, in endothermic reactions, heat is consumed from the environment. This can occur by increasing the entropy of the system, often through the formation of gaseous or dissolved reaction products, which have higher entropy. Since the entropy term in the free-energy change increases with temperature, many endothermic reactions preferably take place at high temperatures. On the contrary, many exothermic reactions such as crystallization occur preferably at lower temperatures. A change in temperature can sometimes reverse the sign of the enthalpy of a reaction, as for the carbon monoxide reduction of molybdenum dioxide:


title: Chemical reaction

text: This reaction to form carbon dioxide and molybdenum is endothermic at low temperatures, becoming less so with increasing temperature. Δ"H"° is zero at , and the reaction becomes exothermic above that temperature.


title: Chemical reaction

text: Changes in temperature can also reverse the direction tendency of a reaction. For example, the water gas shift reaction


title: Chemical reaction

text: is favored by low temperatures, but its reverse is favored by high temperatures. The shift in reaction direction tendency occurs at .


title: Chemical reaction

text: Reactions can also be characterized by their internal energy change, which takes into account changes in the entropy, volume and chemical potentials. The latter depends, among other things, on the activities of the involved substances.


title: Chemical reaction

text: The speed at which reactions take place is studied by reaction kinetics. The rate depends on various parameters, such as:


title: Chemical reaction

text: Several theories allow calculating the reaction rates at the molecular level. This field is referred to as reaction dynamics. The rate "v" of a first-order reaction, which could be the disintegration of a substance A, is given by:


title: Chemical reaction

text: Here "k" is the first-order rate constant, having dimension 1/time, [A]("t") is the concentration at a time "t" and [A] is the initial concentration. The rate of a first-order reaction depends only on the concentration and the properties of the involved substance, and the reaction itself can be described with a characteristic half-life. More than one time constant is needed when describing reactions of higher order. The temperature dependence of the rate constant usually follows the Arrhenius equation:


title: Chemical reaction

text: where "E" is the activation energy and "k" is the Boltzmann constant. One of the simplest models of reaction rate is the collision theory. More realistic models are tailored to a specific problem and include the transition state theory, the calculation of the potential energy surface, the Marcus theory and the Rice–Ramsperger–Kassel–Marcus (RRKM) theory.


title: Chemical reaction

text: In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form:


title: Chemical reaction

text: Two or more reactants yielding one product is another way to identify a synthesis reaction. One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide:


title: Chemical reaction

text: Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.


title: Chemical reaction

text: A decomposition reaction is when a more complex substance breaks down into its more simple parts. It is thus the opposite of a synthesis reaction and can be written as


title: Chemical reaction

text: One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:


title: Chemical reaction

text: In a single displacement reaction, a single uncombined element replaces another in a compound; in other words, one element trades places with another element in a compound These reactions come in the general form of:


title: Chemical reaction

text: One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:


title: Chemical reaction

text: In a double displacement reaction, the anions and cations of two compounds switch places and form two entirely different compounds. These reactions are in the general form:


title: Chemical reaction

text: For example, when barium chloride (BaCl) and magnesium sulfate (MgSO) react, the SO anion switches places with the 2Cl anion, giving the compounds BaSO and MgCl.


title: Chemical reaction

text: Another example of a double displacement reaction is the reaction of lead(II) nitrate with potassium iodide to form lead(II) iodide and potassium nitrate:


title: Chemical reaction

text: In a combustion reaction, an element or compound reacts with an oxidant, usually oxygen, often producing energy in the form of heat or light. Combustion reactions frequently involve a hydrocarbon. For instance, the combustion of 1 mole (114 g) of octane in oxygen


title: Chemical reaction

text: releases 5500 kJ. A combustion reaction can also result from carbon, magnesium or sulfur reacting with oxygen.


title: Chemical reaction

text: Redox reactions can be understood in terms of the transfer of electrons from one involved species (reducing agent) to another (oxidizing agent). In this process, the former species is "oxidized" and the latter is "reduced". Though sufficient for many purposes, these descriptions are not precisely correct. Oxidation is better defined as an increase in oxidation state of atoms and reduction as a decrease in oxidation state. In practice, the transfer of electrons will always change the oxidation state, but there are many reactions that are classed as "redox" even though no electron transfer occurs (such as those involving covalent bonds).


title: Chemical reaction

text: In the following redox reaction, hazardous sodium metal reacts with toxic chlorine gas to form the ionic compound sodium chloride, or common table salt:


title: Chemical reaction

text: In the reaction, sodium metal goes from an oxidation state of 0 (as it is a pure element) to +1: in other words, the sodium lost one electron and is said to have been oxidized. On the other hand, the chlorine gas goes from an oxidation of 0 (it is also a pure element) to −1: the chlorine gains one electron and is said to have been reduced. Because the chlorine is the one reduced, it is considered the electron acceptor, or in other words, induces oxidation in the sodium – thus the chlorine gas is considered the oxidizing agent. Conversely, the sodium is oxidized or is the electron donor, and thus induces a reduction in the other species and is considered the "reducing agent".


title: Chemical reaction

text: Which of the involved reactants would be a reducing or oxidizing agent can be predicted from the electronegativity of their elements. Elements with low electronegativities, such as most metals, easily donate electrons and oxidize – they are reducing agents. On the contrary, many oxides or ions with high oxidation numbers of their non-oxygen atoms, such as , , , , or , can gain one or two extra electrons and are strong oxidizing agents.


title: Chemical reaction

text: For some main-group elements the number of electrons donated or accepted in a redox reaction can be predicted from the electron configuration of the reactant element. Elements try to reach the low-energy noble gas configuration, and therefore alkali metals and halogens will donate and accept one electron, respectively. Noble gases themselves are chemically inactive.


title: Chemical reaction

text: The overall redox reaction can be balanced by combining the oxidation and reduction half-reactions multiplied by coefficients such that the number of electrons lost in the oxidation equals the number of electrons gained in the reduction.


title: Chemical reaction

text: An important class of redox reactions are the electrolytic electrochemical reactions, where electrons from the power supply at the negative electrode are used as the reducing agent and electron withdrawal at the positive electrode as the oxidizing agent. These reactions are particularly important for the production of chemical elements, such as chlorine or aluminium. The reverse process, in which electrons are released in redox reactions and chemical energy is converted to electrical energy, is possible and used in batteries.


title: Chemical reaction

text: In complexation reactions, several ligands react with a metal atom to form a coordination complex. This is achieved by providing lone pairs of the ligand into empty orbitals of the metal atom and forming dipolar bonds. The ligands are Lewis bases, they can be both ions and neutral molecules, such as carbon monoxide, ammonia or water. The number of ligands that react with a central metal atom can be found using the 18-electron rule, saying that the valence shells of a transition metal will collectively accommodate 18 electrons, whereas the symmetry of the resulting complex can be predicted with the crystal field theory and ligand field theory. Complexation reactions also include ligand exchange, in which one or more ligands are replaced by another, and redox processes which change the oxidation state of the central metal atom.


title: Chemical reaction

text: In the Brønsted–Lowry acid–base theory, an acid–base reaction involves a transfer of protons (H) from one species (the acid) to another (the base). When a proton is removed from an acid, the resulting species is termed that acid's conjugate base. When the proton is accepted by a base, the resulting species is termed that base's conjugate acid. In other words, acids act as proton donors and bases act as proton acceptors according to the following equation:


title: Chemical reaction

text: <chem display="block">\underset{acid}{HA} + \underset{base}{B} <=> \underset{conjugated\ base}{A^-} + \underset{conjugated\ acid}{HB+}</chem>


title: Chemical reaction

text: The reverse reaction is possible, and thus the acid/base and conjugated base/acid are always in equilibrium. The equilibrium is determined by the acid and base dissociation constants ("K" and "K") of the involved substances. A special case of the acid-base reaction is the neutralization where an acid and a base, taken at the exact same amounts, form a neutral salt.


title: Chemical reaction

text: Acid-base reactions can have different definitions depending on the acid-base concept employed. Some of the most common are:


title: Chemical reaction

text: Precipitation is the formation of a solid in a solution or inside another solid during a chemical reaction. It usually takes place when the concentration of dissolved ions exceeds the solubility limit and forms an insoluble salt. This process can be assisted by adding a precipitating agent or by the removal of the solvent. Rapid precipitation results in an amorphous or microcrystalline residue and a slow process can yield single crystals. The latter can also be obtained by recrystallization from microcrystalline salts.


title: Chemical reaction

text: Reactions can take place between two solids. However, because of the relatively small diffusion rates in solids, the corresponding chemical reactions are very slow in comparison to liquid and gas phase reactions. They are accelerated by increasing the reaction temperature and finely dividing the reactant to increase the contacting surface area.


title: Chemical reaction

text: The reaction can take place at the solid|gas interface, surfaces at very low pressure such as ultra-high vacuum. Via scanning tunneling microscopy, it is possible to observe reactions at the solid|gas interface in real space, if the time scale of the reaction is in the correct range. Reactions at the solid|gas interface are in some cases related to catalysis.


title: Chemical reaction

text: In photochemical reactions, atoms and molecules absorb energy (photons) of the illumination light and convert it into an excited state. They can then release this energy by breaking chemical bonds, thereby producing radicals. Photochemical reactions include hydrogen–oxygen reactions, radical polymerization, chain reactions and rearrangement reactions.


title: Chemical reaction

text: Many important processes involve photochemistry. The premier example is photosynthesis, in which most plants use solar energy to convert carbon dioxide and water into glucose, disposing of oxygen as a side-product. Humans rely on photochemistry for the formation of vitamin D, and vision is initiated by a photochemical reaction of rhodopsin. In fireflies, an enzyme in the abdomen catalyzes a reaction that results in bioluminescence. Many significant photochemical reactions, such as ozone formation, occur in the Earth atmosphere and constitute atmospheric chemistry.


title: Chemical reaction

text: In catalysis, the reaction does not proceed directly, but through a reaction with a third substance known as catalyst. Although the catalyst takes part in the reaction, forming weak bonds with reactants or intermediates, it is returned to its original state by the end of the reaction and so is not consumed. However, it can be inhibited, deactivated or destroyed by secondary processes. Catalysts can be used in a different phase (heterogeneous) or in the same phase (homogeneous) as the reactants. In heterogeneous catalysis, typical secondary processes include coking where the catalyst becomes covered by polymeric side products. Additionally, heterogeneous catalysts can dissolve into the solution in a solid-liquid system or evaporate in a solid–gas system. Catalysts can only speed up the reaction – chemicals that slow down the reaction are called inhibitors. Substances that increase the activity of catalysts are called promoters, and substances that deactivate catalysts are called catalytic poisons. With a catalyst, a reaction that is kinetically inhibited by high activation energy can take place in the circumvention of this activation energy.


title: Chemical reaction

text: Heterogeneous catalysts are usually solids, powdered in order to maximize their surface area. Of particular importance in heterogeneous catalysis are the platinum group metals and other transition metals, which are used in hydrogenations, catalytic reforming and in the synthesis of commodity chemicals such as nitric acid and ammonia. Acids are an example of a homogeneous catalyst, they increase the nucleophilicity of carbonyls, allowing a reaction that would not otherwise proceed with electrophiles. The advantage of homogeneous catalysts is the ease of mixing them with the reactants, but they may also be difficult to separate from the products. Therefore, heterogeneous catalysts are preferred in many industrial processes.


title: Chemical reaction

text: In organic chemistry, in addition to oxidation, reduction or acid-base reactions, a number of other reactions can take place which involves covalent bonds between carbon atoms or carbon and heteroatoms (such as oxygen, nitrogen, halogens, etc.). Many specific reactions in organic chemistry are name reactions designated after their discoverers.


title: Chemical reaction

text: In a substitution reaction, a functional group in a particular chemical compound is replaced by another group. These reactions can be distinguished by the type of substituting species into a nucleophilic, electrophilic or radical substitution.


title: Chemical reaction

text: In the first type, a nucleophile, an atom or molecule with an excess of electrons and thus a negative charge or partial charge, replaces another atom or part of the "substrate" molecule. The electron pair from the nucleophile attacks the substrate forming a new bond, while the leaving group departs with an electron pair. The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. Examples of nucleophiles are hydroxide ion, alkoxides, amines and halides. This type of reaction is found mainly in aliphatic hydrocarbons, and rarely in aromatic hydrocarbon. The latter have high electron density and enter nucleophilic aromatic substitution only with very strong electron withdrawing groups. Nucleophilic substitution can take place by two different mechanisms, S1 and S2. In their names, S stands for substitution, N for nucleophilic, and the number represents the kinetic order of the reaction, unimolecular or bimolecular.


title: Chemical reaction

text: The S1 reaction proceeds in two steps. First, the leaving group is eliminated creating a carbocation. This is followed by a rapid reaction with the nucleophile.


title: Chemical reaction

text: In the S2 mechanisms, the nucleophile forms a transition state with the attacked molecule, and only then the leaving group is cleaved. These two mechanisms differ in the stereochemistry of the products. S1 leads to the non-stereospecific addition and does not result in a chiral center, but rather in a set of geometric isomers ("cis/trans"). In contrast, a reversal (Walden inversion) of the previously existing stereochemistry is observed in the S2 mechanism.


title: Chemical reaction

text: Electrophilic substitution is the counterpart of the nucleophilic substitution in that the attacking atom or molecule, an electrophile, has low electron density and thus a positive charge. Typical electrophiles are the carbon atom of carbonyl groups, carbocations or sulfur or nitronium cations. This reaction takes place almost exclusively in aromatic hydrocarbons, where it is called electrophilic aromatic substitution. The electrophile attack results in the so-called σ-complex, a transition state in which the aromatic system is abolished. Then, the leaving group, usually a proton, is split off and the aromaticity is restored. An alternative to aromatic substitution is electrophilic aliphatic substitution. It is similar to the nucleophilic aliphatic substitution and also has two major types, S1 and S2


title: Chemical reaction

text: In the third type of substitution reaction, radical substitution, the attacking particle is a radical. This process usually takes the form of a chain reaction, for example in the reaction of alkanes with halogens. In the first step, light or heat disintegrates the halogen-containing molecules producing radicals. Then the reaction proceeds as an avalanche until two radicals meet and recombine.


title: Chemical reaction

text: The addition and its counterpart, the elimination, are reactions that change the number of substituents on the carbon atom, and form or cleave multiple bonds. Double and triple bonds can be produced by eliminating a suitable leaving group. Similar to the nucleophilic substitution, there are several possible reaction mechanisms that are named after the respective reaction order. In the E1 mechanism, the leaving group is ejected first, forming a carbocation. The next step, the formation of the double bond, takes place with the elimination of a proton (deprotonation). The leaving order is reversed in the E1cb mechanism, that is the proton is split off first. This mechanism requires the participation of a base. Because of the similar conditions, both reactions in the E1 or E1cb elimination always compete with the S1 substitution.


title: Chemical reaction

text: The E2 mechanism also requires a base, but there the attack of the base and the elimination of the leaving group proceed simultaneously and produce no ionic intermediate. In contrast to the E1 eliminations, different stereochemical configurations are possible for the reaction product in the E2 mechanism, because the attack of the base preferentially occurs in the anti-position with respect to the leaving group. Because of the similar conditions and reagents, the E2 elimination is always in competition with the S2-substitution.


title: Chemical reaction

text: The counterpart of elimination is an addition where double or triple bonds are converted into single bonds. Similar to substitution reactions, there are several types of additions distinguished by the type of the attacking particle. For example, in the electrophilic addition of hydrogen bromide, an electrophile (proton) attacks the double bond forming a carbocation, which then reacts with the nucleophile (bromine). The carbocation can be formed on either side of the double bond depending on the groups attached to its ends, and the preferred configuration can be predicted with the Markovnikov's rule. This rule states that "In the heterolytic addition of a polar molecule to an alkene or alkyne, the more electronegative (nucleophilic) atom (or part) of the polar molecule becomes attached to the carbon atom bearing the smaller number of hydrogen atoms."


title: Chemical reaction

text: If the addition of a functional group takes place at the less substituted carbon atom of the double bond, then the electrophilic substitution with acids is not possible. In this case, one has to use the hydroboration–oxidation reaction, wherein the first step, the boron atom acts as electrophile and adds to the less substituted carbon atom. In the second step, the nucleophilic hydroperoxide or halogen anion attacks the boron atom.


title: Chemical reaction

text: While the addition to the electron-rich alkenes and alkynes is mainly electrophilic, the nucleophilic addition plays an important role in the carbon-heteroatom multiple bonds, and especially its most important representative, the carbonyl group. This process is often associated with elimination so that after the reaction the carbonyl group is present again. It is, therefore, called an addition-elimination reaction and may occur in carboxylic acid derivatives such as chlorides, esters or anhydrides. This reaction is often catalyzed by acids or bases, where the acids increase the electrophilicity of the carbonyl group by binding to the oxygen atom, whereas the bases enhance the nucleophilicity of the attacking nucleophile.


title: Chemical reaction

text: Nucleophilic addition of a carbanion or another nucleophile to the double bond of an alpha, beta-unsaturated carbonyl compound can proceed via the Michael reaction, which belongs to the larger class of conjugate additions. This is one of the most useful methods for the mild formation of C–C bonds.


title: Chemical reaction

text: Some additions which can not be executed with nucleophiles and electrophiles can be succeeded with free radicals. As with the free-radical substitution, the radical addition proceeds as a chain reaction, and such reactions are the basis of the free-radical polymerization.


title: Chemical reaction

text: In a rearrangement reaction, the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. These include hydride shift reactions such as the Wagner-Meerwein rearrangement, where a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon. Most rearrangements are associated with the breaking and formation of new carbon-carbon bonds. Other examples are sigmatropic reaction such as the Cope rearrangement.


title: Chemical reaction

text: Cyclic rearrangements include cycloadditions and, more generally, pericyclic reactions, wherein two or more double bond-containing molecules form a cyclic molecule. An important example of cycloaddition reaction is the Diels–Alder reaction (the so-called [4+2] cycloaddition) between a conjugated diene and a substituted alkene to form a substituted cyclohexene system.


title: Chemical reaction

text: Whether a certain cycloaddition would proceed depends on the electronic orbitals of the participating species, as only orbitals with the same sign of wave function will overlap and interact constructively to form new bonds. Cycloaddition is usually assisted by light or heat. These perturbations result in a different arrangement of electrons in the excited state of the involved molecules and therefore in different effects. For example, the [4+2] Diels-Alder reactions can be assisted by heat whereas the [2+2] cycloaddition is selectively induced by light. Because of the orbital character, the potential for developing stereoisomeric products upon cycloaddition is limited, as described by the Woodward–Hoffmann rules.


title: Chemical reaction

text: Biochemical reactions are mainly controlled by enzymes. These proteins can specifically catalyze a single reaction so that reactions can be controlled very precisely. The reaction takes place in the active site, a small part of the enzyme which is usually found in a cleft or pocket lined by amino acid residues, and the rest of the enzyme is used mainly for stabilization. The catalytic action of enzymes relies on several mechanisms including the molecular shape ("induced fit"), bond strain, proximity and orientation of molecules relative to the enzyme, proton donation or withdrawal (acid/base catalysis), electrostatic interactions and many others.


title: Chemical reaction

text: The biochemical reactions that occur in living organisms are collectively known as metabolism. Among the most important of its mechanisms is the anabolism, in which different DNA and enzyme-controlled processes result in the production of large molecules such as proteins and carbohydrates from smaller units. Bioenergetics studies the sources of energy for such reactions. Important energy sources are glucose and oxygen, which can be produced by plants via photosynthesis or assimilated from food and air, respectively. All organisms use this energy to produce adenosine triphosphate (ATP), which can then be used to energize other reactions.


title: Chemical reaction

text: Chemical reactions are central to chemical engineering, where they are used for the synthesis of new compounds from natural raw materials such as petroleum, mineral ores, and oxygen in air. It is essential to make the reaction as efficient as possible, maximizing the yield and minimizing the number of reagents, energy inputs and waste. Catalysts are especially helpful for reducing the energy required for the reaction and increasing its reaction rate.


title: Chemical reaction

text: Some specific reactions have their niche applications. For example, the thermite reaction is used to generate light and heat in pyrotechnics and welding. Although it is less controllable than the more conventional oxy-fuel welding, arc welding and flash welding, it requires much less equipment and is still used to mend rails, especially in remote areas.


title: Chemical reaction

text: Mechanisms of monitoring chemical reactions depend strongly on the reaction rate. Relatively slow processes can be analyzed in situ for the concentrations and identities of the individual ingredients. Important tools of real-time analysis are the measurement of pH and analysis of optical absorption (color) and emission spectra. A less accessible but rather efficient method is the introduction of a radioactive isotope into the reaction and monitoring how it changes over time and where it moves to; this method is often used to analyze the redistribution of substances in the human body. Faster reactions are usually studied with ultrafast laser spectroscopy where utilization of femtosecond lasers allows short-lived transition states to be monitored at a time scaled down to a few femtoseconds.


title: Larry Elder

text: Laurence Allen Elder (born April 27, 1952) is an American right-wing political commentator and conservative talk radio host. Elder hosts "The Larry Elder Show", based in California. The show began as a local program on Los Angeles radio station KABC in 1993 and ran until 2008, followed by a second run on KABC from 2010 to 2014. The show is nationally syndicated, first through ABC Radio Networks from 2002 to 2007 and then Salem Media Group from 2015 to 2022. He maintains ties to "The Epoch Times", a far-right newspaper published by the Falun Gong movement.


title: Larry Elder

text: Elder, a former attorney, has written nonfiction books and a nationally syndicated column through Creators Syndicate. In 2021, he made his first run for elected office, as a Republican candidate in the recall election of California's Democratic governor, Gavin Newsom. The recall was defeated by a wide margin, with Elder placing first among the replacement candidates.


title: Larry Elder

text: Laurence Allen Elder was born in Los Angeles and grew up in the city's Pico-Union and South Central areas, the middle child of three brothers. His father Randolph (1915–2011), who was born in Athens, Georgia, was a sergeant in the United States Marine Corps during World War II and moved to California from Georgia after the war during the Second Great Migration. After working as a janitor at Nabisco, Randolph Elder opened a cafe in Pico-Union around 1962. Following his father's death in 2011, Larry Elder recalled: "Gruff and blunt, my dad often intimidated my two brothers and me. But we never doubted his love or his commitment to his family." In 2013, Elder and his brother Kirk accepted a Congressional Gold Medal from U.S. Representative Dana Rohrabacher on their father's behalf. Larry Elder's mother Viola (née Conley, 1924–2006) was originally from Toney, Alabama. She was a clerical worker for the United States Department of War during World War II. His father was a Republican, and his mother a Democrat.


title: Larry Elder

text: An honors student who also took advanced courses at Fairfax High School, Elder graduated from Crenshaw High School in 1970 and earned his Bachelor of Arts degree in political science in 1974 from Brown University. He then earned a Juris Doctor from University of Michigan Law School in 1977.


title: Larry Elder

text: After graduation from law school, Elder joined the Cleveland law firm Squire, Sanders & Dempsey. In 1980, he founded Laurence A. Elder and Associates, a legal executive search firm. Elder stepped down from operating Elder and Associates around 1987 but continued to own the firm until 1995. Elder's license to practice law in Ohio has been administratively suspended since December 2005, according to The Supreme Court of Ohio Attorney Directory website, which notes a failure to file the proper records.


title: Larry Elder

text: Elder began co-hosting "Fabric", a topic-oriented television show produced by Dennis Goulden that aired on Cleveland's PBS member station WVIZ in 1988.


title: Larry Elder

text: In 1997, he hosted the PBS program "National Desk" along with fellow conservatives Fred Barnes and Laura Ingraham. Elder hosted the segments "Redefining Racism: Fresh Voices From Black America" and "Title IX and Women in Sports: What's Wrong With This Picture", which criticized Title IX.


title: Larry Elder

text: In 2000, Elder won a Los Angeles Area Emmy Award for his KCAL-TV News special "Making Waves – LAUSD". Between 2000 and 2001, Elder hosted the court series "Moral Court", distributed by Warner Brothers Television. In 2004, he hosted "The Larry Elder Show", a syndicated talk show distributed by Warner Bros.


title: Larry Elder

text: In 2005, he created a self-financed film called "Michael & Me", in which he offers a rebuttal to filmmaker Michael Moore's "Bowling for Columbine".


title: Larry Elder

text: In 2007, Elder was one of the rotating talk hosts auditioning for the slot vacated by the now-canceled "Imus in the Morning" on MSNBC. However, the job went to Joe Scarborough instead.


title: Larry Elder

text: Elder is a columnist with Creators Syndicate. His newspaper and online column are carried by "Investor's Business Daily", "World Net Daily", "Townhall.com", "Jewish World Review" and "FrontPage Magazine". He hosts a video series published by "The Epoch Times".


title: Larry Elder

text: Elder hosted a weekday evening talk show on Los Angeles talk radio station KABC from 1994 until December 2008. He then launched a daily live podcast as well as a webcast in December 2009. Elder returned to KABC in September 2010.


title: Larry Elder

text: In December 2014, Elder was fired from KABC following his afternoon broadcast. He was honored with a star on the Hollywood Walk of Fame in 2015. In June 2015, Elder joined the lineup of CRN Digital Talk Radio Networks. In August 2015, "The Larry Elder Show" began national syndication through the Salem Radio Network, including Los Angeles station KRLA.


title: Larry Elder

text: Jean Guerrero, in a 2020 interview on NPR, said that Elder had told her that he had invited Stephen Miller on his radio show as a guest a total of 69 times, having been impressed with Miller after he had first called in to the show as a high school student. Miller, who cites Elder as an influence, later became a Trump administration official and the architect of Trump's immigration policies.


title: Larry Elder

text: Elder abruptly left his Salem Radio afternoon slot as of , after a six-year run. His regular fill-in host, Carl Jackson, who had substituted for Elder's during the latter's run for the California Governor seat, has again been named as the temporary fill-in host until a permanent replacement is named.


title: Larry Elder

text: In the late 1980s, Elder wrote op-eds for local newspapers in Cleveland. In 1998, Elder began writing a nationally syndicated column through Creators Syndicate. Elder wrote a weekly column for the "Los Angeles Daily News" until April 2012.


title: Larry Elder

text: "Roll Call" reported that Elder contemplated a possible run for the United States Senate against California Senator Barbara Boxer in 2010.


title: Larry Elder

text: In July 2021, Elder announced his candidacy to replace Governor Gavin Newsom in the 2021 California gubernatorial recall election. He said that he was encouraged to run by fellow conservative talk-radio figure Dennis Prager, a mentor to Elder.


title: Larry Elder

text: California Secretary of State Shirley Weber initially omitted Elder's name from the list of candidates to be on the ballot, saying that he failed to submit complete tax return information that was required according to Senate Bill 27, which was enacted in 2019; the law mandated tax return disclosure for both presidential and gubernatorial candidates in order to appear on a "primary" ballot (the presidential requirement was later struck down by the courts). Elder sued, saying that his paperwork was properly submitted and that Weber was required to fix the alleged errors. On July 21, 2021, Judge Laurie Earl of the Sacramento County Superior Court ordered Elder's reinstatement to the recall ballot, holding that Weber improperly disqualified Elder, who had "substantially complied" with disclosure requirements, and that the recall election's tax return disclosure requirements imposed by Secretary of State Weber were invalid, since the special recall election was not a "direct primary election". Weber's office did not appeal the ruling.


title: Larry Elder

text: After his entry, Elder had been regarded as the front-runner on the election's replacement question. He refused to participate in debates with other Republican recall candidates, such as former San Diego Mayor Kevin Faulconer, state Assemblyman Kevin Kiley, and businessowner John Cox, and had refused to share a stage with certain other candidates at Republican Party events. Former California Governor Pete Wilson was one of Elder's campaign advisors. If elected Governor, Elder pledged to replace one of California's two Democratic senators, Dianne Feinstein, with a Republican.


title: Larry Elder

text: In September 2021, while the recall election was underway, Elder claimed without evidence that there would be "shenanigans" in the voting process. Four days before election day, and before election results were known, a website paid for by Elder's campaign already referred to the election having "twisted results", baselessly stating that analyses "detected fraud in California resulting in Governor Gavin Newsom being reinstated as governor."


title: Larry Elder

text: On the night of the election, after Newsom defeated the recall effort, Elder told his supporters to be "gracious in defeat", stating that "we may have lost the battle, but we are going to win the war", proceeding to repeatedly criticize Newsom.


title: Larry Elder

text: In January 2022, Elder announced that he would not run against Newsom in the state's gubernatorial election later that year, and would instead focus on a new political action committee called "Elder for America" in order to help Republicans win back the House and Senate.


title: Larry Elder

text: Elder holds conservative and right-wing views. Elder is a registered Republican; in 2021, he stated that he had voted for the Republican candidate in every presidential election since 1980 after voting for Democrat Jimmy Carter in 1976. Elder labels himself a "small-l libertarian" as opposed to a member of the Libertarian Party.


title: Larry Elder

text: He is an ardent supporter of former President Donald Trump, frequently praising him on Twitter. He was an early supporter of Trump's 2016 candidacy for president. In 2019, speaking to an audience about the election of Trump, Elder said, "It was a miracle. He is almost God-sent." After Joe Biden won the 2020 presidential election and Donald Trump made false claims of fraud while refusing to concede, Elder said that he did not believe that Biden won the 2020 election fairly. Elder has argued that it is unfair to blame Trump for the January 6, 2021 attack on the Capitol by a pro-Trump mob. Elder opposed tariffs imposed by Trump and Trump's decision to draw down U.S. troops from Afghanistan.


title: Larry Elder

text: The Sacramento Bee pointed out his ties to The Epoch Times, a newspaper considered to be far-right, which is published by the Falun Gong movement.


title: Larry Elder

text: In his 2000 book, "The Ten Things You Can't Say In America", Elder laid out a 10-point plan to "save America". He called for abolishing the Internal Revenue Service, creating a national sales tax, reducing government by 80%, ending welfare and entitlements, abolishing the minimum wage, and eliminating corporate taxes.


title: Larry Elder

text: Elder opposes minimum wage laws, arguing that "The ideal minimum wage is $0.00." He opposes universal basic income. Elder opposes California's unpaid family leave law. In his 2020 film "Uncle Tom: An Oral History of the American Black Conservative", Elder criticizes the War on Poverty.


title: Larry Elder

text: On a CNN "Crossfire" segment in 2013 along with New Jersey Governor Chris Christie, Elder criticized Christie for accepting the "architecture of the welfare state" and claimed that "government took almost 50 percent of the American people's money" through mandates, a claim he supported by referring to an analysis by the conservative advocacy group Americans for Tax Reform. PolitiFact rated his claim "Mostly False".


title: Larry Elder

text: Elder has been critical of public-sector labor unions, especially the California Teachers Association. He contends that some 15,000 California teachers are "incompetent" and previously proposed that thousands of teachers in the state be fired. He later said that he favored more charter schools and private schools instead.


title: Larry Elder

text: In August 2021, Elder came under criticism for his long history of disparaging statements about women. Elder has contended that "Women know less than men about political issues, economics, and current events" when citing a 2017 Cambridge study by Toni Alexander Ihme and Markus Tausendpfund; mocked women who took part in the 2017 Women's March as "obese"; mocked premenstrual syndrome by saying PMS stands for "Punish My Spouse"; endorsed pregnancy discrimination by employers; reposted an article on his website that likened single mothers on welfare to stray cats; and claimed that statistics about domestic violence against women are exaggerated to promote feminism. Elder has asserted that Democrats achieve more success among women voters because they have "emotionally driven, but often unsound policies."


title: Larry Elder

text: Elder has often denied that a gender wage gap exists. Elder contends that employers should be allowed to discriminate in employment against women who plan to have children, and in his 2002 book he wrote that women who choose to have children are not "dedicated" to their jobs and suggested that they lacked a "commitment" to work. Elder reiterated these views in 2021, while he ran for governor, after fellow Republican candidate Kevin Faulconer criticized Elder's views.


title: Larry Elder

text: Elder opposes abortion, calling it "murder." He has argued that "Roe v. Wade" should be overturned, calling the decision "one of the worst decisions that the Supreme Court ever handed down." He believes that abortion laws should be decided at the state level.


title: Larry Elder

text: Elder has made anti-LGBT remarks on Twitter and has repeatedly used male pronouns when referring to transgender women, such as Playboy model Ines Rau and fellow gubernatorial candidate Caitlyn Jenner.


title: Larry Elder

text: In 2021, Elder accused California of having a "soft-on-crime ethos"; he opposes a California law that banned police from using certain chokeholds. Elder opposes 2014 California Proposition 47, which reclassified as misdemeanors many lower-level drug and property crimes that had formerly been felonies, and said that if elected governor he would press for the proposition to be repealed.


title: Larry Elder

text: During his media career, Elder published and gave airtime to misinformation and fringe views on scientific topics, such as secondhand tobacco smoke, climate change, and COVID-19 treatments.


title: Larry Elder

text: In a 2000 book, Elder suggested that the health hazards of secondhand tobacco smoke had been exaggerated, rejecting the scientific consensus that secondhand smoke is a serious threat that caused 2.5 million deaths in the half-century before 2014.


title: Larry Elder

text: Elder's website once described climate change as a "myth"; in a 2008 interview, he called climate change a "crock," disparaged Republicans such as John McCain and George W. Bush, who acknowledged climate change, and said that global warming is not a "big peril" to planet Earth. In 2021, Elder acknowledged that the climate is warming, but refused to accept the overwhelming scientific consensus that human activity is the primary contributor, claiming that concern about climate change is "alarmism."


title: Larry Elder

text: In 2021, Elder pledged to remove current statewide public health mandates for state government workers in California, such as COVID-19 vaccine requirements, face mask requirements, or regular COVID-19 testing. Elder encouraged "people in high-risk categories, people who are older" to be vaccinated but said that "young people" do not need to be vaccinated. In 2021, Elder did not challenge a call-in listener to his radio show who espoused COVID-19 misinformation suggesting that COVID-19 vaccines were dangerous and part of a Bill Gates-orchestrated plot, and a page on Elder's website promoted the call-in listener's comments by saying, "You'll want to hear this physician's take on the vaccines."


title: Larry Elder

text: Elder has proposed suspending or waiving the requirements of the California Environmental Quality Act, contending that doing so would speed up housing construction.


title: Larry Elder

text: Elder does not believe in systemic racism, calling it a lie. He is a critic of the Black Lives Matter movement, blaming it for rising crime. As part of his criticism of welfare, he stated that it is more harmful to Black families than slavery ever was. He has proposed school choice as a solution for poor performance of Black children in school.


title: Larry Elder

text: Elder was married for two years to a female physician, who was also a longtime friend of his. They divorced in 1994 because she wanted to have children and he did not. Elder later dated Patricia Stewart from 1996 to 2012, and they have remained friends since their separation. Elder then dated Alexandra Datig, a longtime former radio producer for him, and was engaged to her from 2013 until 2015.


title: Larry Elder

text: In 2011 episodes of his radio program, Elder disclosed that he had twice been accused of sexual harassment and denied both allegations. In one case, Elder defended himself by implying that the woman was too unattractive for him to sexually harass, saying, "If you had seen her, you would know that the picture would be a complete defense. I'm just saying."


title: Larry Elder

text: In 2021, Elder's former fiancée Alexandra Datig accused him of abuse. Datig said that Elder had demanded she show devotion by having "Larry's Girl" tattooed on herself and, during an argument, brandished a gun threateningly at her while "high" on cannabis. After Datig's allegations became public, "The Sacramento Bee" editorial board and fellow candidates Kevin Faulconer and Caitlyn Jenner called for Elder to withdraw from the race. Elder denied Datig's accusations and called them "salacious allegations".


title: Carnivorous plant

text: Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants still generate some of their energy from photosynthesis. Carnivorous plants have adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs.


title: Carnivorous plant

text: They can be found on all continents except Antarctica, as well as many Pacific islands. In 1875 Charles Darwin published "Insectivorous Plants", the first treatise to recognize the significance of carnivory in plants, describing years of painstaking research.


title: Carnivorous plant

text: True carnivory is believed to have evolved independently at least 12 times in five different orders of flowering plants, and is represented by more than a dozen genera. This classification includes at least 583 species that attract, trap, and kill prey, absorbing the resulting available nutrients. Venus flytrap ("Dionaea muscipula"), pitcher plant ("Cephalotus follicularis"), and bladderwort ("Utricularia gibba") can be seen as exemplars of key traits genetically associated with carnivory: trap leaf development, prey digestion, and nutrient absorption.


title: Carnivorous plant

text: The number of known species has increased by approximately 3 species per year since the year 2000. Additionally, over 300 protocarnivorous plant species in several genera show some but not all of these characteristics. A 2020 assessment has found that roughly one quarter are threatened with extinction from human actions.


title: Carnivorous plant

text: These traps may be active or passive, depending on whether movement aids the capture of prey. For example, "Triphyophyllum" is a passive flypaper that secretes mucilage, but whose leaves do not grow or move in response to prey capture. Meanwhile, sundews are active flypaper traps whose leaves undergo rapid acid growth, which is an expansion of individual cells as opposed to cell division. The rapid acid growth allows the sundews' tentacles to bend, aiding in the retention and digestion of prey.


title: Carnivorous plant

text: Characterised by an internal chamber, pitfall traps are thought to have evolved independently at least six times. This particular adaptation is found within the families Sarraceniaceae "(Darlingtonia, Heliamphora, Sarracenia"), Nepenthaceae ("Nepenthes"), and Cephalotaceae ("Cephalotus"). Within the family Bromeliaceae"," pitcher morphology and carnivory evolved twice "(Brocchinia" and "Catopsis)." Because these families do not share a common ancestor who also had pitfall trap morphology, carnivorous pitchers are an example of convergent evolution.


title: Carnivorous plant

text: A passive trap, pitfall traps attract prey with nectar bribes secreted by the peristome and bright flower-like anthocyanin patterning within the pitcher. The linings of most pitcher plants are covered in a loose coating of waxy flakes which are slippery for insects, causing them to fall into the pitcher. Once within the pitcher structure, digestive enzymes or mutualistic species break down the prey into an absorbable form for the plant. Water can become trapped within the pitcher, making a habitat for other flora and fauna. This type of 'water body' is called a Phytotelma.


title: Carnivorous plant

text: The simplest pitcher plants are probably those of "Heliamphora", the marsh pitcher plant. In this genus, the traps are clearly derived from a simple rolled leaf whose margins have sealed together. These plants live in areas of high rainfall in South America such as Mount Roraima and consequently have a problem ensuring their pitchers do not overflow. To counteract this problem, natural selection has favoured the evolution of an overflow similar to that of a bathroom sink—a small gap in the zipped-up leaf margins allows excess water to flow out of the pitcher.


title: Carnivorous plant

text: In the genus "Sarracenia", the problem of pitcher overflow is solved by an operculum, which is essentially a flared leaflet that covers the opening of the rolled-leaf tube and protects it from rain. Possibly because of this improved waterproofing, "Sarracenia" species secrete enzymes such as proteases and phosphatases into the digestive fluid at the bottom of the pitcher; Most "Heliamphora" rely on bacterial digestion alone with the exception of a single species, Heliamphora tatei, which does produce digestive enzymes. The enzymes digest the proteins and nucleic acids in the prey, releasing amino acids and phosphate ions, which the plant absorbs. In at least one species, "Sarracenia flava", the nectar bribe is laced with coniine, a toxic alkaloid also found in hemlock, which probably increases the efficiency of the traps by intoxicating prey.


title: Carnivorous plant

text: "Darlingtonia californica", the cobra plant, possesses an adaptation also found in "Sarracenia psittacina" and, to a lesser extent, in "Sarracenia minor": the operculum is balloon-like and almost seals the opening to the tube. This balloon-like chamber is pitted with areolae, chlorophyll-free patches through which light can penetrate. Insects, mostly ants, enter the chamber via the opening underneath the balloon. Once inside, they tire themselves trying to escape from these false exits, until they eventually fall into the tube. Prey access is increased by the "fish tails", outgrowths of the operculum that give the plant its name. Some seedling "Sarracenia" species also have long, overhanging opercular outgrowths; "Darlingtonia" may therefore represent an example of neoteny.


title: Carnivorous plant

text: The second major group of pitcher plants are the monkey cups or tropical pitcher plants of the genus "Nepenthes". In the hundred or so species of this genus, the pitcher is borne at the end of a tendril, which grows as an extension to the midrib of the leaf. Most species catch insects, although the larger ones, such as "Nepenthes rajah", also occasionally take small mammals and reptiles. "Nepenthes bicalcarata" possesses two sharp thorns that project from the base of the operculum over the entrance to the pitcher. These likely serve to lure insects into a precarious position over the pitcher mouth, where they may lose their footing and fall into the fluid within.


title: Carnivorous plant

text: The pitfall trap has evolved independently in at least two other groups. The Albany pitcher plant "Cephalotus follicularis" is a small pitcher plant from Western Australia, with moccasin-like pitchers. The rim of its pitcher's opening (the peristome) is particularly pronounced (both secrete nectar) and provides a thorny overhang to the opening, preventing trapped insects from climbing out.


title: Carnivorous plant

text: The final carnivore with a pitfall-like trap is the bromeliad "Brocchinia reducta". Like most relatives of the pineapple, the tightly packed, waxy leaf bases of the strap-like leaves of this species form an urn. In most bromeliads, water collects readily in this urn and may provide habitats for frogs, insects and, more useful for the plant, diazotrophic (nitrogen-fixing) bacteria. In "Brocchinia", the urn is a specialised insect trap, with a loose, waxy lining and a population of digestive bacteria.


title: Carnivorous plant

text: The flypaper trap utilises sticky mucilage or glue. The leaf of flypaper traps is studded with mucilage-secreting glands, which may be short (like those of the butterworts), or long and mobile (like those of many sundews). Flypapers have evolved independently at least five times. There is evidence that some clades of flypaper traps have evolved from morphologically more complex traps such as pitchers.


title: Carnivorous plant

text: In the genus "Pinguicula", the mucilage glands are quite short (sessile), and the leaf, while shiny (giving the genus its common name of 'butterwort'), does not appear carnivorous. However, this belies the fact that the leaf is an extremely effective trap of small flying insects (such as fungus gnats), and its surface responds to prey by relatively rapid growth. This thigmotropic growth may involve rolling of the leaf blade (to prevent rain from splashing the prey off the leaf surface) or dishing of the surface under the prey to form a shallow digestive pit.


title: Carnivorous plant

text: The sundew genus ("Drosera") consists of over 100 species of active flypapers whose mucilage glands are borne at the end of long tentacles, which frequently grow fast enough in response to prey (thigmotropism) to aid the trapping process. The tentacles of "D. burmanii" can bend 180° in a minute or so. Sundews are extremely cosmopolitan and are found on all the continents except the Antarctic mainland. They are most diverse in Australia, the home to the large subgroup of pygmy sundews such as "D. pygmaea" and to a number of tuberous sundews such as "D. peltata", which form tubers that aestivate during the dry summer months. These species are so dependent on insect sources of nitrogen that they generally lack the enzyme nitrate reductase, which most plants require to assimilate soil-borne nitrate into organic forms.


title: Carnivorous plant

text: Similar to "Drosera" is the Portuguese dewy pine, "Drosophyllum", which differs from the sundews in being passive. Its leaves are incapable of rapid movement or growth. Unrelated, but similar in habit, are the Australian rainbow plants ("Byblis"). "Drosophyllum" is unusual in that it grows under near-desert conditions; almost all other carnivores are either bog plants or grow in moist tropical areas.


title: Carnivorous plant

text: Recent molecular data (particularly the production of plumbagin) indicate that the remaining flypaper, "Triphyophyllum peltatum", a member of the Dioncophyllaceae, is closely related to "Drosophyllum" and forms part of a larger clade of carnivorous and non-carnivorous plants with the Droseraceae, Nepenthaceae, Ancistrocladaceae and Plumbaginaceae. This plant is usually encountered as a liana, but in its juvenile phase, the plant is carnivorous. This may be related to a requirement for specific nutrients for flowering.


title: Carnivorous plant

text: The only two active snap traps—the Venus flytrap ("Dionaea muscipula") and the waterwheel plant ("Aldrovanda vesiculosa")—had a common ancestor with the snap trap adaptation, which had evolved from an ancestral lineage that utilized flypaper traps. Their trapping mechanism has also been described as a "mouse trap", "bear trap" or "man trap", based on their shape and rapid movement. However, the term "snap trap" is preferred as other designations are misleading, particularly with respect to the intended prey. "Aldrovanda" is aquatic and specialized in catching small invertebrates; "Dionaea" is terrestrial and catches a variety of arthropods, including spiders.


title: Carnivorous plant

text: The traps are very similar, with leaves whose terminal section is divided into two lobes, hinged along the midrib. Trigger hairs (three on each lobe in "Dionaea muscipula", many more in the case of "Aldrovanda") inside the trap lobes are sensitive to touch. When a trigger hair is bent, stretch-gated ion channels in the membranes of cells at the base of the trigger hair open, generating an action potential that propagates to cells in the midrib. These cells respond by pumping out ions, which may either cause water to follow by osmosis (collapsing the cells in the midrib) or cause rapid acid growth. The mechanism is still debated, but in any case, changes in the shape of cells in the midrib allow the lobes, held under tension, to snap shut, flipping rapidly from convex to concave and interring the prey. This whole process takes less than a second. In the Venus flytrap, closure in response to raindrops and blown-in debris is prevented by the leaves having a simple memory: for the lobes to shut, two stimuli are required, 0.5 to 30 seconds apart. According to a recent study, calcium molecules move dynamically within the cells of the plant's leaves when a carnivorous plant touches live prey. Changing calcium levels make leaves move to catch prey, likely by producing more hormones related to defense.


title: Carnivorous plant

text: The snapping of the leaves is a case of thigmonasty (undirected movement in response to touch). Further stimulation of the lobe's internal surfaces by the struggling insects causes the lobes to close even tighter (thigmotropism), sealing the lobes hermetically and forming a stomach in which digestion occurs over a period of one to two weeks. Once this process is triggered, it cannot be reversed and requires more stimulation to trigger the next steps. Leaves can be reused three or four times before they become unresponsive to stimulation, depending on the growing conditions.


title: Carnivorous plant

text: Bladder traps are exclusive to the genus "Utricularia", or bladderworts. The bladders (vesiculae) pump ions out of their interiors. Water follows by osmosis, generating a partial vacuum inside the bladder. The bladder has a small opening, sealed by a hinged door. In aquatic species, the door has a pair of long trigger hairs. Aquatic invertebrates such as "Daphnia" touch these hairs and deform the door by lever action, releasing the vacuum. The invertebrate is sucked into the bladder, where it is digested. Many species of "Utricularia" (such as "U. sandersonii") are terrestrial, growing in waterlogged soil, and their trapping mechanism is triggered in a slightly different manner. Bladderworts lack roots, but terrestrial species have anchoring stems that resemble roots. Temperate aquatic bladderworts generally die back to a resting turion during the winter months, and "U. macrorhiza" appears to regulate the number of bladders it bears in response to the prevailing nutrient content of its habitat.


title: Carnivorous plant

text: A lobster-pot trap is a chamber that is easy to enter, and whose exit is either difficult to find or obstructed by inward-pointing bristles. Lobster pots are the trapping mechanism in "Genlisea", the corkscrew plants. These plants appear to specialise in aquatic protozoa. A "Y"-shaped modified leaf allows prey to enter but not exit. Inward-pointing hairs force the prey to move in a particular direction. Prey entering the spiral entrance that coils around the upper two arms of the "Y" are forced to move inexorably towards a stomach in the lower arm of the "Y", where they are digested. Prey movement is also thought to be encouraged by water movement through the trap, produced in a similar way to the vacuum in bladder traps, and probably evolutionarily related to it.


title: Carnivorous plant

text: Outside of "Genlisea", features reminiscent of lobster-pot traps can be seen in "Sarracenia psittacina", "Darlingtonia californica", and, some horticulturalists argue, "Nepenthes aristolochioides".


title: Carnivorous plant

text: The trapping mechanism of the sundew "Drosera glanduligera" combines features of both flypaper and snap traps; it has been termed a "catapult-flypaper trap". However, this is not the only combination traps. "Nepenthes jamban" is a combination of pitfall and flypaper traps because it has a sticky pitcher fluid.


title: Carnivorous plant

text: Most Sumatran nepenthes, like "N. inermis", also have this method. For example, "N. dubia" and "N. flava" also use this method.


title: Carnivorous plant

text: To be defined as carnivorous, a plant must first exhibit an adaptation of some trait specifically for the attraction, capture, or digestion of prey. Only one trait needs to have evolved that fits this adaptive requirement, as many current carnivorous plant genera lack some of the above-mentioned attributes. The second requirement is the ability to absorb nutrients from dead prey and gain a fitness advantage from the integration of these derived nutrients (mostly amino acids and ammonium ions) either through increased growth or pollen and/or seed production. However, plants that may opportunistically utilise nutrients from dead animals without specifically seeking and capturing fauna are excluded from the carnivorous definition. The second requirement also differentiates carnivory from defensive plant characteristics that may kill or incapacitate insects without the advantage of nutrient absorption. Due to the observation that many currently classified carnivores lack digestive enzymes for breaking down nutrients and instead rely upon mutualistic and symbiotic relationships with bacteria, ants, or insects, this adaptation has been added to the carnivorous definition. Despite this, there are cases where plants appear carnivorous, in that they fulfill some of the above definition, but are not truly carnivorous. Some botanists argue that there is a spectrum of carnivory found in plants: from completely non-carnivorous plants like cabbages, to borderline carnivores, to unspecialised and simple traps, like "Heliamphora", to extremely specialised and complex traps, like that of the Venus flytrap.


title: Carnivorous plant

text: A possible carnivore is the genus "Roridula"; the plants in this genus produce sticky leaves with resin-tipped glands and look extremely similar to some of the larger sundews. However, they do not directly benefit from the insects they catch. Instead, they form a mutualistic symbiosis with species of assassin bug (genus "Pameridea"), which eat the trapped insects. The plant benefits from the nutrients in the bugs' feces. By some definitions this would still constitute botanical carnivory.


title: Carnivorous plant

text: A number of species in the Martyniaceae (previously Pedaliaceae), such as "Ibicella lutea", have sticky leaves that trap insects. However, these plants have not been shown conclusively to be carnivorous. Likewise, the seeds of Shepherd's Purse, urns of "Paepalanthus bromelioides", bracts of "Passiflora foetida", and flower stalks and sepals of triggerplants ("Stylidium") appear to trap and kill insects, but their classification as carnivores is contentious.


title: Carnivorous plant

text: Two genera of liverwort, "Colura" and "Pleurozia", have sac-shaped leaves that trap and kill ciliates and may digest them.


title: Carnivorous plant

text: Specialized multicellular secretion glands produce digestive fluid that smother, kill, digest prey and make a solution to assimilate released nutrients. Saccharides are often found in plants that have adhesive traps or plants that use viscous secretion to retain captured prey. The digestion fluid is often nutrient poor and has ions K, Na, Ca and Mg (for species in the "Nepenthes" genera for example), along with numerous proteins which vary across genera. Peroxidases are also involved for some species. The body of the prey is decomposed by a cocktail of hydrolytic enzymes which are stored in sub-cellular compartments or synthesized over and over as needed.


title: Carnivorous plant

text: Proteins of digestive fluid include proteases, chitinases (partly destroy exoskeleton of insects), phosphatases, and nucleases.


title: Carnivorous plant

text: Charles Darwin spent 16 years growing carnivorous plants, experimenting with them in the greenhouse of his home in Kent, Down House. In his pioneering book "Insectivorous Plants" (1875) Darwin concluded that carnivory in plants was convergent, writing that carnivorous genera "Utricularia" and "Nepenthes" were not "at all related to the [carnivorous family] Droseraceae".  This remained a subject of debate for over a century. In 1960, Leon Croizat concluded that carnivory was monophyletic, and placed all the carnivorous plants together at the base of the angiosperms.  Molecular studies over the past 30 years have led to a wide consensus that Darwin was correct, with studies showing that carnivory evolved at least six times in the angiosperms, and that trap designs such as pitcher traps and flypaper traps are analogous rather than homologous.


title: Carnivorous plant

text: Researchers using molecular data have concluded that carnivory evolved independently in the Poales ("Brocchinia" and "Catopsis" in the Bromeliaceae), the Caryophyllales (Droseraceae, Nepenthaceae, Drosophyllaceae, Dioncophyllaceae), the Oxalidales ("Cephalotus"), the Ericales (Sarraceniaceae and Roridulaceae), and twice in the Lamiales (Lentibulariaceae and independently in Byblidaceae).  The oldest evolution of an existing carnivory lineage has been dated to 85.6 million years ago, with the most recent being "Brocchinia reducta" in the Bromeliaceae estimated at only 1.9 mya.


title: Carnivorous plant

text: The evolution of carnivorous plants is obscured by the paucity of their fossil record. Very few fossils have been found, and then usually only as seed or pollen. Carnivorous plants are generally herbs, and their traps are produced by primary growth. They generally do not form readily fossilisable structures such as thick bark or wood.


title: Carnivorous plant

text: Researchers are increasingly using genome sequencing technology to examine the development of carnivorous species and relationships between them. Genetic evidence suggests that carnivory developed by co-opting and repurposing existing genes which had established functions in flowering plants, rather than by "hijacking" genes from other types of organisms.


title: Carnivorous plant

text: Most carnivorous plants live in habitats with high light, waterlogged soils, and extremely low soil nitrogen and phosphorus, producing the ecological impetus to derive nitrogen from an alternate source. High-light environments allowed for the trade-off between photosynthetic leaves and photosynthetically-inefficient, prey-capturing traps. To compensate for the photosynthetically-inefficient material, the nutrients obtained through carnivory would need to increase photosynthesis by investing in more leaf mass (i.e. growth). Consequently, when there is a shortage of nutrients, sufficient light and water, the capture and digestion of prey has the greatest impact on photosynthetic gains, thus favoring the evolution of plant adaptations which allowed for more effective, efficient carnivory.


title: Carnivorous plant

text: Due to the required energy and resource allocations for carnivorous adaptations (e.g. the production of lures, digestive enzymes, modified leaf structures, and the decreased rate of photosynthesis over total leaf area), some authors argue that carnivory is an evolutionary "last resort" when nitrogen and phosphorus are extremely limited in an ecosystem.


title: Carnivorous plant

text: Despite meager fossil evidence, much can be deduced from the structure of current traps and their ecological interactions. It is widely believed that carnivory evolved under extremely nutrient-poor conditions, leading to a cost-benefit model for botanical carnivory. Cost-benefit models are used under the assumption that there is a set amount of potential energy available to an organism, which leads to trade-offs wherein energy is allocated to certain functions to maximize competitive ability and fitness. For carnivory, the trait could only evolve if the increase in nutrients from capturing prey exceeded the cost of investment in carnivorous adaptations.


title: Carnivorous plant

text: Pitfall traps are derived from rolled leaves, which evolved several independent times through convergent evolution. The vascular tissues of "Sarracenia" is a case in point. The keel along the front of the trap contains a mixture of leftward- and rightward-facing vascular bundles, as would be predicted from the fusion of the edges of an adaxial (stem-facing) leaf surface. Flypapers also show a simple evolutionary gradient from sticky, non-carnivorous leaves, through passive flypapers to active forms. Molecular data show the "Dionaea"–"Aldrovanda" clade is closely related to "Drosera", and evolved from active flypaper traps into snap traps.


title: Carnivorous plant

text: It has been suggested that all trap types are modifications of a similar basic structure: the hairy leaf. Hairy (or more specifically, stalked-glandular) leaves can catch and retain drops of rainwater, especially if shield-shaped or peltate, thus promoting bacteria growth. Insects land on the leaf, become mired by the surface tension of the water, and suffocate. Bacteria jumpstart decay, releasing from the corpse nutrients that the plant can absorb through its leaves. This foliar feeding can be observed in most non-carnivorous plants.


title: Carnivorous plant

text: Plants that were better at retaining insects or water therefore had a selective advantage. Rainwater can be retained by cupping the leaf, and pitfall traps may have evolved simply by selection pressure for the production of more deeply cupped leaves, followed by "zipping up" of the margins and subsequent loss of most of the hairs. Alternatively, insects can be retained by making the leaf stickier by the production of mucilage, leading to flypaper traps.


title: Carnivorous plant

text: The only traps that are unlikely to have descended from a hairy leaf or sepal are the carnivorous bromeliads ("Brocchinia" and "Catopsis"): These plants use the urn – a characteristic part of all bromeliads, not just the carnivorous ones – for a new purpose, and build on it by the production of wax and the other paraphernalia of carnivory.


title: Carnivorous plant

text: The lobster-pot traps of "Genlisea" are difficult to interpret. They may have developed from bifurcated pitchers that later specialised on ground-dwelling prey; or, perhaps, the prey-guiding protrusions of bladder traps became more substantial than the net-like funnel found in most aquatic bladderworts. Whatever their origin, the helical shape of the lobster pot is an adaptation that displays as much trapping surface as possible in all directions when buried in moss.


title: Carnivorous plant

text: The traps of the bladderworts may have derived from pitchers that specialised in aquatic prey when flooded, like "Sarracenia psittacina" does today. Escaping prey in terrestrial pitchers have to climb or fly out of a trap, and both of these can be prevented by wax, gravity and narrow tubes. However, a flooded trap can be swum out of, so in "Utricularia", a one-way lid may have developed to form the door of a proto-bladder. Later, this may have become active by the evolution of a partial vacuum inside the bladder, tripped by prey brushing against trigger hairs on the door of the bladder.


title: Carnivorous plant

text: The active glue traps use rapid plant movements to trap their prey. Rapid plant movement can result from actual growth, or from rapid changes in cell turgor, which allow cells to expand or contract by quickly altering their water content. Slow-moving flypapers like "Pinguicula" exploit growth, while the Venus flytrap uses such rapid turgor changes which make glue unnecessary. The stalked glands that once made glue became teeth and trigger hairs in species with active snap traps — an example of natural selection hijacking preexisting structures for new functions.


title: Carnivorous plant

text: Recent taxonomic analysis of the relationships within the Caryophyllales indicate that the Droseraceae, "Triphyophyllum", Nepenthaceae and "Drosophyllum", while closely related, are embedded within a larger clade that includes non-carnivorous groups such as the tamarisks, Ancistrocladaceae, Polygonaceae and Plumbaginaceae.


title: Carnivorous plant

text: The tamarisks possess specialised salt-excreting glands on their leaves, as do several of the Plumbaginaceae (such as the sea lavender, "Limonium"), which may have been co-opted for the excretion of other chemicals, such as proteases and mucilage. Some of the Plumbaginaceae ("e.g." "Ceratostigma") also have stalked, vascularised glands that secrete mucilage on their calyces and aid in seed dispersal and possibly in protecting the flowers from crawling parasitic insects. The balsams (such as "Impatiens"), which are closely related to the Sarraceniaceae and "Roridula", similarly possess stalked glands.


title: Carnivorous plant

text: Philcoxia is unique in the Plantaginaceae as a result of its subterranean stems and leaves, which have been shown to be used in the capture of nematodes. These plants grow in sand in Brazil, where they are likely to receive other nutrients. Like many other types of carnivorous plant, stalked glands are seen on the leaves. Enzymes on the leaves are used to digest the worms and release their nutrients.


title: Carnivorous plant

text: Botanical carnivory has evolved in several independent families peppered throughout the angiosperm phylogeny, showing that carnivorous traits underwent convergent evolution multiple times to create similar morphologies across disparate families. Results of genetic testing published in 2017 found an example of convergent evolution - a digestive enzyme with the same functional mutations across unrelated lineages.


title: Carnivorous plant

text: Carnivorous plants are widespread but rather rare. They are almost entirely restricted to habitats such as bogs, where soil nutrients are extremely limiting, but where sunlight and water are readily available. Only under such extreme conditions is carnivory favored to an extent that makes the adaptations advantageous.


title: Carnivorous plant

text: The archetypal carnivore, the Venus flytrap, grows in soils with almost immeasurable nitrate and calcium levels. Plants need nitrogen for protein synthesis, calcium for cell wall stiffening, phosphate for nucleic acid synthesis, and iron and magnesium for chlorophyll synthesis. The soil is often waterlogged, which favours the production of toxic ions such as ammonium, and its pH is an acidic 4 to 5. Ammonium can be used as a source of nitrogen by plants, but its high toxicity means that concentrations high enough to fertilise are also high enough to cause damage.


title: Carnivorous plant

text: However, the habitat is warm, sunny, constantly moist, and the plant experiences relatively little competition from low growing "Sphagnum" moss. Still, carnivores are also found in very atypical habitats. "Drosophyllum lusitanicum" is found around desert edges and "Pinguicula valisneriifolia" on limestone (calcium-rich) cliffs.


title: Carnivorous plant

text: In all the studied cases, carnivory allows plants to grow and reproduce using animals as a source of nitrogen, phosphorus and possibly potassium. However, there is a spectrum of dependency on animal prey. Pygmy sundews are unable to use nitrate from soil because they lack the necessary enzymes (nitrate reductase in particular). Common butterworts ("Pinguicula vulgaris") can use inorganic sources of nitrogen better than organic sources, but a mixture of both is preferred. European bladderworts seem to use both sources equally well. Animal prey makes up for differing deficiencies in soil nutrients.


title: Carnivorous plant

text: Plants use their leaves to intercept sunlight. The energy is used to reduce carbon dioxide from the air with electrons from water to make sugars (and other biomass) and a waste product, oxygen, in the process of photosynthesis. Leaves also respire, in a similar way to animals, by burning their biomass to generate chemical energy. This energy is temporarily stored in the form of ATP (adenosine triphosphate), which acts as an energy currency for metabolism in all living things. As a waste product, respiration produces carbon dioxide.


title: Carnivorous plant

text: For a plant to grow, it must photosynthesise more than it respires. Otherwise, it will eventually exhaust its biomass and die. The potential for plant growth is net photosynthesis, the total gross gain of biomass by photosynthesis, minus the biomass lost by respiration. Understanding carnivory requires a cost-benefit analysis of these factors.


title: Carnivorous plant

text: In carnivorous plants, the leaf is not just used to photosynthesise, but also as a trap. Changing the leaf shape to make it a better trap generally makes it less efficient at photosynthesis. For example, pitchers have to be held upright, so that only their opercula directly intercept light. The plant also has to expend extra energy on non-photosynthetic structures like glands, hairs, glue and digestive enzymes. To produce such structures, the plant requires ATP and respires more of its biomass. Hence, a carnivorous plant will have both decreased photosynthesis and increased respiration, making the potential for growth small and the cost of carnivory high.


title: Carnivorous plant

text: Being carnivorous allows the plant to grow better when the soil contains little nitrate or phosphate. In particular, an increased supply of nitrogen and phosphorus makes photosynthesis more efficient, because photosynthesis depends on the plant being able to synthesise very large amounts of the nitrogen-rich enzyme RuBisCO (ribulose-1,5-"bis"-phosphate carboxylase/oxygenase), the most abundant protein on Earth.


title: Carnivorous plant

text: It is intuitively clear that the Venus flytrap is more carnivorous than "Triphyophyllum peltatum". The former is a full-time moving snap-trap; the latter is a part-time, non-moving flypaper. The energy "wasted" by the plant in building and fuelling its trap is a suitable measure of the carnivory of the trap.


title: Carnivorous plant

text: Using this measure of investment in carnivory, a model can be proposed. Above is a graph of carbon dioxide uptake (potential for growth) against trap respiration (investment in carnivory) for a leaf in a sunny habitat containing no soil nutrients at all. Respiration is a straight line sloping down under the horizontal axis (respiration produces carbon dioxide). Gross photosynthesis is a curved line above the horizontal axis: as investment increases, so too does the photosynthesis of the trap, as the leaf receives a better supply of nitrogen and phosphorus. Eventually another factor (such as light intensity or carbon dioxide concentration) will become more limiting to photosynthesis than nitrogen or phosphorus supply. As a result, increasing the investment will not make the plant grow better. The net uptake of carbon dioxide, and therefore, the plant's potential for growth, must be positive for the plant to survive. There is a broad span of investment where this is the case, and there is also a non-zero optimum. Plants investing more or less than this optimum will take up less carbon dioxide than an optimal plant, and hence growing less well. These plants will be at a selective disadvantage. At zero investment the growth is zero, because a non-carnivorous plant cannot survive in a habitat with absolutely no soil-borne nutrients. Such habitats do not exist, so for example, "Sphagnum" absorbs the tiny amounts of nitrates and phosphates in rain very efficiently and also forms symbioses with diazotrophic cyanobacteria.


title: Carnivorous plant

text: In a habitat with abundant soil nutrients but little light (as shown above), the gross photosynthesis curve will be lower and flatter, because light will be more limiting than nutrients. A plant can grow at zero investment in carnivory; this is also the "optimum" investment for a plant, as any investment in traps reduces net photosynthesis (growth) to less than the net photosynthesis of a plant that obtains its nutrients from soil alone.


title: Carnivorous plant

text: Carnivorous plants exist between these two extremes: the less limiting light and water are, and the more limiting soil nutrients are, the higher the optimum investment in carnivory, and hence the more obvious the adaptations will be to the casual observer.


title: Carnivorous plant

text: The most obvious evidence for this model is that carnivorous plants tend to grow in habitats where water and light are abundant and where competition is relatively low: the typical bog. Those that do not tend to be even more fastidious in some other way. "Drosophyllum lusitanicum" grows where there is little water, but it is even more extreme in its requirement for bright light and low disturbance than most other carnivores. "Pinguicula valisneriifolia" grows in soils with high levels of calcium but requires strong illumination and lower competition than many butterworts.


title: Carnivorous plant

text: In general, carnivorous plants are poor competitors, because they invest too heavily in structures that have no selective advantage in nutrient-rich habitats. They succeed only where other plants fail. Carnivores are to nutrients what cacti are to water. Carnivory only pays off when the nutrient stress is high and where light is abundant. When these conditions are not met, some plants give up carnivory temporarily. "Sarracenia" spp. produce flat, non-carnivorous leaves (phyllodes) in winter. Light levels are lower than in summer, so light is more limiting than nutrients, and carnivory does not pay. The lack of insects in winter exacerbates the problem. Damage to growing pitcher leaves prevents them from forming proper pitchers, and again, the plant produces a phyllode instead.


title: Carnivorous plant

text: Many other carnivores shut down in some seasons. Tuberous sundews die back to tubers in the dry season, bladderworts to turions in winter, and non-carnivorous leaves are made by most butterworts and "Cephalotus" in the less favourable seasons. "Utricularia macrorhiza" varies the number of bladders it produces based on the expected density of prey. Part-time carnivory in "Triphyophyllum peltatum" may be due to an unusually high need for potassium at a certain point in the life cycle, just before flowering.


title: Carnivorous plant

text: The more carnivorous a plant is, the less conventional its habitat is likely to be. Venus flytraps live in a very specialised habitat, whereas less carnivorous plants ("Byblis", "Pinguicula") are found in less unusual habitats (i.e., those typical for non-carnivores). "Byblis" and "Drosophyllum" both come from relatively arid regions and are both passive flypapers, arguably the lowest maintenance form of trap. Venus flytraps filter their prey using the teeth around the trap's edge, so as not to waste energy on hard-to-digest prey. In evolution, laziness pays, because energy can be used for reproduction, and short-term benefits in reproduction will outweigh long-term benefits in anything else.


title: Carnivorous plant

text: Carnivory rarely pays, so even carnivorous plants avoid it when there is too little light or an easier source of nutrients, and they use as few carnivorous features as are required at a given time or for a given prey item. There are very few habitats stressful enough to make investing biomass and energy in trigger hairs and enzymes worthwhile. Many plants occasionally benefit from animal protein rotting on their leaves, but carnivory that is obvious enough for the casual observer to notice is rare.


title: Carnivorous plant

text: Bromeliads seem very well preadapted to carnivory, but only one or two species can be classified as truly carnivorous. By their very shape, bromeliads will benefit from increased prey-derived nutrient input. In this sense, bromeliads are probably carnivorous, but their habitats are too dark for more extreme, recognisable carnivory to evolve. Most bromeliads are epiphytes, and most epiphytes grow in partial shade on tree branches. "Brocchinia reducta", on the other hand, is a ground dweller.


title: Carnivorous plant

text: Many carnivorous plants are not strongly competitive and rely on circumstances to suppress dominating vegetation. Accordingly, some of them rely on fire ecology for their continued survival.


title: Carnivorous plant

text: For the most part carnivorous plant populations are not dominant enough to be dramatically significant, ecologically speaking, but there is an impressive variety of organisms that interact with various carnivorous plants in sundry relationships of kleptoparasitism, commensalism, and mutualism. For example, small insectivores such as tree frogs often exploit the supply of prey to be found in pitcher plants, and the frog "Microhyla nepenthicola" actually specialises in such habitats. Certain crab spiders such as "Misumenops nepenthicola" live largely on the prey of "Nepenthes", and other, less specialised, spiders may build webs where they trap insects attracted by the smell or appearance of the traps; some scavengers, detritivores, and also organisms that harvest or exploit those in turn, such as the mosquito "Wyeomyia smithii" are largely or totally dependent on particular carnivorous plants. Plants such as "Roridula" species combine with specialised bugs ("Pameridea roridulae") in benefiting from insects trapped on their leaves.


title: Carnivorous plant

text: Associations with species of pitcher plants are so many and varied that the study of "Nepenthes" infauna is something of a discipline in its own right. "Camponotus schmitzi", the diving ant, has an intimate degree of mutualism with the pitcher plant "Nepenthes bicalcarata"; it not only retrieves prey and detritus from beneath the surface of the liquid in the pitchers, but repels herbivores, and cleans the pitcher peristome, maintaining its slippery nature. The ants have been reported to attack struggling prey, hindering their escape, so there might be an element of myrmecotrophy to the relationship. Numerous species of mosquitoes lay their eggs in the liquid, where their larvae play various roles, depending on species; some eat microbes and detritus, as is common among mosquito larvae, whereas some species of "Toxorhynchites" also breed in pitchers, and their larvae are predators of other species of mosquito larvae. Apart from the crab spiders on pitchers, an actual small, red crab "Geosesarma malayanum" will enter the fluid, robbing and scavenging, though reputedly it does so at some risk of being captured and digested itself.


title: Carnivorous plant

text: "Nepenthes rajah" has a remarkable mutualism with two unrelated small mammals, the mountain treeshrew ("Tupaia montana") and the summit rat ("Rattus baluensis"). The tree shrews and the rats defecate into the plant's traps while visiting them to feed on sweet, fruity secretions from glands on the pitcher lids. The tree shrew also has a similar relationship with at least two other giant species of "Nepenthes". More subtly, Hardwicke's woolly bat ("Kerivoula hardwickii"), a small species, roosts beneath the operculum (lid) of "Nepenthes hemsleyana". The bat's excretions that land in the pitcher pay for the shelter, as it were. To the plant the excreta are more readily assimilable than intact insects would be.


title: Carnivorous plant

text: There also is a considerable list of "Nepenthes" endophytes; these are microbes other than pathogens that live in the tissues of pitcher plants, often apparently harmlessly.


title: Carnivorous plant

text: Another important area of symbiosis between carnivorous plants and insects is pollination. While many species of carnivorous plant can reproduce asexually via self-pollination or vegetative propagation, many carnivorous plants are insect-pollinated. Outcross pollination is beneficial as it increases genetic diversity. This means that carnivorous plants undergo an evolutionary and ecological conflict often called the pollinator-prey conflict. There are several ways by which carnivorous plants reduce the strain of the pollinator-prey conflict. For long-lived plants, the short-term loss of reproduction may be offset by the future growth made possible by resources obtained from prey. Other plants might "target" different species of insect for pollination and prey using different olfactory and visual cues.


title: Carnivorous plant

text: Approximately half of the plant species assessed by the IUCN are considered threatened (vulnerable, endangered or critically endangered). Common threats are habitat loss as a result of agriculture, collection of wild plants, pollution, invasive species, residential and commercial development, energy production, mining, transportation services, geologic events, climate change, severe weather, and many other anthropogenic activities. Species in the same genus were proven to face similar threats. Threat by continent is deemed highly variable, with threats found for 19 species in North America, 15 species in Asia, seven species in Europe, six species in South America, two species in Africa, and one species in Australia Indicator species' such as Sarracenia reveal positive associations with regard to these threats. Certain threats are also positively correlated themselves, with residential and commercial development, natural systems modifications, invasive species, and pollution having positive associations. Conservation research is aiming to further quantify the effects of threats, such as pollution, on carnivorous plants, as well as to quantify the extinction risks. Only 17% of species had been assessed as of 2011, according to the IUCN. Carnivorous plant conservation will help maintain important ecosystems and prevent secondary extinctions of specialist species that rely on them such as foundation species which may seek refuge or rely on certain plants for their existence. Research suggests a holistic approach, targeted at the habitat-level of carnivorous plants, may be required for successful conservation.


title: Carnivorous plant

text: The classification of all flowering plants is currently in a state of flux. In the Cronquist system, the Droseraceae and Nepenthaceae were placed in the order Nepenthales, based on the radial symmetry of their flowers and their possession of insect traps. The Sarraceniaceae was placed either in the Nepenthales, or in its own order, the Sarraceniales. The Byblidaceae, Cephalotaceae, and Roridulaceae were placed in the Saxifragales; and the Lentibulariaceae in the Scrophulariales (now subsumed into the Lamiales).


title: Carnivorous plant

text: In more modern classification, such as that of the Angiosperm Phylogeny Group, the families have been retained, but they have been redistributed amongst several disparate orders. It is also recommended that "Drosophyllum" be considered in a monotypic family outside the rest of the Droseraceae, probably more closely allied to the Dioncophyllaceae. The current recommendations are shown below (only carnivorous genera are listed):


title: Carnivorous plant

text: In horticulture, carnivorous plants are considered a curiosity or a rarity, but are becoming more common in cultivation with the advent of mass-production tissue-culture propagation techniques. Venus flytraps are still the most commonly grown, usually available at garden centers and hardware stores, sometimes offered alongside other easy-to-grow varieties. Nurseries that specialise in growing carnivorous plants exclusively also exist, more uncommon or demanding varieties of carnivorous plants can be obtained from specialist nurseries. California Carnivores is a notable example of such a nursery in the US that specialises in the cultivation of carnivorous plants. It is owned and operated by horticulturalist Peter D'Amato. Rob Cantley's Borneo Exotics in Sri Lanka is a large nursery that sells worldwide.