Crassulacean acid metabolism

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Crassulacean acid metabolism

Crassulacean acid metabolism, also known as CAM photosynthesis, is an elaborate carbon fixation

Carbon fixation

Carbon fixation is a process found in autotrophs , usually driven by photosynthesis, whereby carbon dioxide is changed into organic materials. Carbon fixation can also be carried out by the process of calcification in marine, calcifying organisms such as Emiliania huxleyi....
pathway in some plant

Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s. These plants fix carbon dioxide during the night, storing it as the four carbon acid malate. The is released during the day, where it is concentrated around the enzyme

Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
RuBisCO

RuBisCO

Ribulose-1,5-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO, is an enzyme that is used in the Calvin cycle to catalyze the first major step of carbon fixation, a process by which the atoms of atmospheric carbon dioxide are made available to organisms in the form of fuel molecules such as sucrose....
, increasing the efficiency of photosynthesis.

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Encyclopedia

Crassulacean acid metabolism, also known as CAM photosynthesis, is an elaborate carbon fixation

Carbon fixation

Plant

Enzyme

RuBisCO

Stoma

In botany, a stoma is a pore, found in the leaf and stem epidermis that is used forgas exchange. The pore is formed by a pair of specialized parenchyma cells known as guard cells which are responsible for regulating the size of the opening....
ta to remain shut during the day; therefore it is especially common in plants adapted to arid conditions.

Historical background

CAM was first discovered in the late 1940s. It was observed by the botanists Ranson and Thomas, in the Crassulaceae

Crassulaceae

The Crassulaceae, or orpine family, is a family of dicotyledons. They store water in their succulent leaves. They are found worldwide, but mostly occur in the Northern Hemisphere and southern Africa, typically in dry and/or cold areas where water may be scarce....
family of succulents (which includes jade plant

Jade plant

Commonly known as jade plant, friendship tree or Money Plant, Crassula ovata is a succulent plant with small pink or white flowers....
s and sedum

Sedum

Sedum is the large stonecrop genus of the Crassulaceae, representing about 400 species of leaf succulents, found throughout the northern hemisphere, varying from annual and creeping herbs to shrubs....
s). Its name refers to acid metabolism in Crassulaceae, not the metabolism of Crassulacean acid.

Overview of CAM: a two-part cycle

CAM is a mechanism whereby is concentrated around RuBisCO by day, while the enzyme is operating at peak capacity. This concentration of increases RuBisCO's efficiency, as it is prone to operate in the "reverse" direction via photorespiration

Photorespiration

Photorespiration is the alternate pathway for production of glyceraldehyde 3-phosphate by RuBisCO, the main enzyme of the light-independent reactions of photosynthesis ....
- utilizing oxygen to break down the reaction products the plant would rather it was producing. It differs from metabolism

C4 carbon fixation

During the night

CAM plants open their stomata during the cooler and more humid night-time hours, permitting the uptake of carbon dioxide with minimal water loss.

The carbon dioxide is converted to soluble molecules, which can be readily stored by the plant at a sensible concentration.

The chemical pathway involves a three-carbon compound phosphoenolpyruvate

Phosphoenolpyruvate

Phosphoenolpyruvic acid , or phosphoenolpyruvate as the anion, is an important chemical compound in biochemistry. It has the high-energy phosphate bond found in living organisms, and is involved in glycolysis and gluconeogenesis....
(PEP), to which a molecule is added. This forms a new molecule, oxaloacetate, which in turn forms a malate. Oxaloacetate and malate are built around a skeleton of four carbons, hence the term . Malate can be readily stored by the plant in vacuoles within individual cells.

The next day...

Malate can be broken down on demand, releasing a molecule of as it is converted to pyruvate. The pyruvate can be phosphorylated (i.e. have a phosphate group added by the "energy carrier" ATP

Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
) to regenerate the PEP with which the plant started, ready to be spurred into action the next night. But it is the release of that makes the cycle worth the plant's while. It is directed to the stroma

Stroma

Stroma may refer to:*Stroma, Scotland, an island off the northern coast of Scotland*Stroma , the connective, functionally supportive framework of a biological cell, tissue, or organ...
of chloroplasts: the sites at which photosynthesis is most active. There, it is provided to RuBisCO in greater concentration, increasing the efficiency of the molecule, and therefore producing more sugars per unit photosynthesis.

The benefits of CAM

A great deal of energy is expended during CAM by the production and subsequent destruction of malate. This is in part countered by the increased efficiency of RuBisCO, but the more important benefit to the plant is the ability to leave most leaf stomata closed during the day. CAM plants are most common in environments, where water comes at a premium. Being able to keep stomata closed during the hottest and driest part of the day reduces the loss of water through evapotranspiration, allowing CAM plants to grow in environments that would otherwise be far too dry. plants, for example, lose 97% of the water they uptake through the roots to transpiration - a high cost avoided by CAM plants.

Comparison with metabolism

The pathway

C4 carbon fixation

C4 carbon fixation is one of three biochemical mechanisms, along with C3 carbon fixation and CAM photosynthesis, functioning in land plants to "fix" carbon dioxide for sugar production through photosynthesis....
bears resemblance to CAM; both act to concentrate around RuBisCO, thereby increasing usefulness. CAM concentrates it in time, providing during the day, and not at night, when respiration is the dominant reaction. plants, on the contrary, concentrate spatially, with a RuBisCO reaction centre in a "bundle sheath cell" being inundated with .

How to spot a CAM plant

CAM can be considered an adaptation to arid conditions. CAM plants often display other xerophytic characters, such as thick, reduced leaves with a low surface-area

Surface area

Surface area is how much exposed area an object has. It is expressed in square units. If an object has flat Face , its surface area can be calculated by adding together the areas of its faces....
-to-volume ratio; thick cuticle

Cuticle

In biology, a cuticle or cuticula is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or part of an organism, that provide protection....
; and stomata sunken into pits. Some shed their leaves during the dry season; others (the succulents) store water in vacuole

Vacuole

A vacuole is a membrane organelle which is present in all eukaryotic cells. Vacuoles are essentially enclosed compartments which are filled with fluid such as water or various enzymes, though in certain cases they may contain solids which have been engulfed....
s.

CAM plants are not only good at retaining water, but use nitrogen very efficiently. However, due to their stomata being closed by day, they are less efficient at absorption. This limits the amount of carbon they have available for growth.

CAM plants can also be recognised as plants which have sour tasting leaves increasing during nights but sweet tasting leaves increasing during days. This is due to the malic acid being stored in the vacuoles of the plant cells during the night, and its being used up during the day.

Biochemistry of Crassulacean Acid Metabolism

Plants with Crassulacean Acid Metabolism (CAM plants) must control storage of carbon dioxide

Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
and its reduction to branched carbohydrates in space and time.

At low temperatures (frequently at night), when CAM plants open their guard cells, carbon dioxide molecules diffuse into the spongy mesophyll's intracellular spaces and finally get into the cytoplasm

Cytoplasm

The cytoplasm is the part of a Cell that is enclosed within the plasma membrane. In eukaryote cells the cytoplasm contains organelles, such as mitochondrion, that are filled with liquid kept separate from the rest of the cytoplasm by biological membranes....
. Here, they can meet phosphoenolpyruvate

Phosphoenolpyruvate

Phosphoenolpyruvic acid , or phosphoenolpyruvate as the anion, is an important chemical compound in biochemistry. It has the high-energy phosphate bond found in living organisms, and is involved in glycolysis and gluconeogenesis....
(PEP), which is a phosphorylated triosephosphate. During this time, CAM plants are synthesizing a protein called PEP carboxylase kinase

Kinase

In chemistry and biochemistry, a kinase, alternatively known as a phosphotransferase, is a type of enzyme that transfers phosphate groups from High-energy phosphate donor molecules, such as adenosine triphosphate, to specific target molecules ; the process is termed phosphorylation ...
(PEP-C kinase), which expression can be inhibited by high temperatures (frequently at daylight) and the presence of malate. PEP-C kinase phosphorylates its target enzyme PEP carboxylase (PEP-C). Phosphorylation

Phosphorylation

Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Protein phosphorylation in particular plays a significant role in a wide range of cellular processes....
dramatically enhanced the enzyme‘s capability to catalyze the formation of oxalacetate that can be subsequently transformed into malate by NAD malate dehydrogenase. Malate is then transported via malate shuttles into the vacuole, where it is converted into the storage form malic acid

Malic acid

Malic acid is an organic compound with the formula HO2CCH2CHOHCO2H. This dicarboxylic acid is the active ingredient in many sour or tart foods....
. In contrast to PEP-C kinase, PEP-C is synthesized all the time but almost inhibited at daylight either by dephosphorylation via PEP-C phosphatase or directly by binding malate. The latter is not possible at low temperatures, since malate is efficiently transported into the vacuole whereas PEP-C kinase readily inverts dephosphorylation

Dephosphorylation

Dephosphorylation is the essential process of removing phosphate groups from an organic compound by hydrolysis. Its opposite is phosphorylation....
.

At daylight, CAM plants close their guard cells and discharged malate that is subsequently transported into chloroplast

Chloroplast

Chloroplasts are organelles found in plant cells and other eukaryote organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve Thermodynamic free energy in the form of Adenosine triphosphate and reduce NADP to NADPH through a complex set of processes called photosynthesis....
s. There, depending on plant species, it is cleaved into pyruvate and carbon dioxide either by malic enzyme or PEP carboxykinase. Carbon dioxide is then introduced into the Calvin cycle

Calvin cycle

The Calvin cycle is a series of biochemistry reactions that take place in the Stroma of chloroplasts in photosynthesis organisms. It was discovered by Melvin Calvin, James Bassham and Andrew Benson at the University of California, Berkeley ....
, a coupled and self-recovering enzyme system, which is used to build branched carbohydrates. The by-product pyruvate can be further degraded in the mitochondrial citric acid cycle

Citric acid cycle

The citric acid cycle ? also known as the tricarboxylic acid cycle ; the Krebs cycle; or, more rarely, the Szent-Gy?rgyi-Krebs cycle) ? is a series of enzyme-catalysed chemical reactions of central importance in all living cell s that use oxygen as part of cellular respiration....
and therefore, provides additional carbon dioxide molecules for the calvin cycle. Alternatively, pyruvate can be also used to recover PEP via pyruvate phosphate dikinase, a high energy step, which requires ATP

Adenosine triphosphate

Phosphate

A phosphate, an inorganic chemical, is a Salt of phosphoric acid. Inorganic phosphates are mining to obtain phosphorus for use in agriculture and industry....
. In the following cold night, PEP is finally exported into the cytoplasm, where it is involved in fixing carbon dioxide via malate.

Ecological and Taxonomic Distribution of CAM Plants

The majority of plants possessing Crassulacean Acid Metabolism are either epiphytes (e.g. orchids, bromeliads) or succulent xerophytes (e.g. cacti, cactoid Euphorbias), but it is also found in hemiepiphytes (e.g. Clusia), lithophytes (e.g. Sedum, Sempervivum), terrestrial bromeliads, hydrophytes (e.g. Isoetes, Crassula (Tillaea), and from a halophyte (Mesembryanthemum crystallinum), a non-succulent terrestrial plant (Dodonaea viscosa) and a mangrove associate (Sesuvium portulacastrum). Portulacaria afra is the only plant known to display both CAM and C4 pathways.

Crassulacean Acid Metabolism has evolved convergently many times. It occurs in 16,000 species (about 7% of plants), belonging to over 300 genera and around 40 families. It is found in quillwort

Quillwort

Iso?tes, also written Isoetes and commonly known as the Quillworts, is the genus of plants in the class Isoetopsida and order Isoetales....
s (relatives of club mosses), in ferns, and in gymnosperms, but the great majority of CAM plants are angiosperms (flowering plants).

The following list summarises the taxonomic distribution of CAM plants.

Division	Class/Angiosperm group	Order	Family	Plant Type	Clade involved
Lycopodiophyta Lycopodiophyta The Division Lycopodiophyta is a vascular plant subdivision of the Kingdom Plantae. It is the oldest extant vascular plant division at around 420 million years old, and includes some of the most "primitive" extant species....	Isoetopsida Isoetopsida The Isoetopsida is a class of the Lycopodiophyta. All living plants belong to the genus Isoetes in the order Isoetales. The order Isoetales is sometimes placed in the class Isoetopsida, sometimes in the Selaginellopsida or Lycopsida....	Isoetales	Isoetaceae	hydrophyte	Isoetes (the sole genus of class Isoetopsida) - I. howellii (seasonally submerged), I. macrospora, I. bolanderi, I. engelmanni, I. lacustris, I. sinensis, I. storkii, I. kirkii
Pteridophyta	Polypodiopsida	Polypodiales Polypodiales The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas....	Polypodiaceae Polypodiaceae Polypodiaceae is a Family of polypod ferns, which includes more than 60 genera divided into several tribe s and containing around 1,000 species....	epiphyte, lithophyte	CAM is recorded from Microsorium, Platycerium Platycerium *Platycerium* is a genus of ~ 18 fern species in the Polypod family, Polypodiaceae. Ferns in this genus are widely known as Staghorn or Elkhorn ferns due to their uniquely-shaped fronds.... and Polypodium Polypodium *Polypodium* is a genus of between 75-100 species of true ferns, widely distributed throughout the world, with the highest species diversity in the tropics.... , Pyrrosia and Drymoglossum and Microgramma Microgramma (fern) *Microgramma* is a genus of ferns in the family Polypodiaceae. Most species in the genus are restricted to Central America and South America....
	Pteridopsida Pteridopsida The Pteridopsida is a class of plants in the Division Fern that includes all the leptosporangiate ferns. In the recent 2006 classification by Smith et al....	Pteridales Pteridales The Pteridales are ferns that have their sorus in linear strips under the edge of the leaf tissue, usually with the edge of the lamina reflexed over....	Vittariaceae Vittariaceae Vittariaceae is a family of ferns in the order Pteridales. Members of the family are primarily epiphyte in tropical regions and all have simple leaves with sorus that follow the veins and lack true indusium; the sori are most often marginal with a false indusium formed from the reflexed leaf margin....	epiphyte	Vittaria Vittaria *Vittaria* is a genus of fern in family Vittariaceae. It contains the following species :* Vittaria longipes, Sodiro... Anetium citrifolium
Cycadophyta	Cycadopsida	Cycadales	Zamiaceae Zamiaceae The Zamiaceae are a family of cycads that are superficially palm or fern-like. They are divided into two subfamilies with eight genera and about 150 species in the tropical and warm temperate regions of Africa, Australia and North America and South America....		Dioon edule Dioon edule *Dioon edule* is a cycadophyta native to Mexico, also known as *palma de la Virgen.Two subspecies are knownDioon edule subsp....
Pinophyta Pinophyta The conifers, division Pinophyta, also known as division Coniferae, are one of 13 or 14 division level taxon within the Plant. They are Conifer cone-bearing seed plants with Vascular plant tissue; all extant conifers are woody plants, the great majority being trees with just a few being shrubs....	Gnetopsida	Welwitschiales	Welwitschiaceae	xerophyte	Welwitschia mirabilis (the sole species of the order Welwitschiales)
Magnoliophyta	magnoliids	Magnoliales Magnoliales Magnoliales is an order of flowering plants....	Piperaceae Piperaceae Piperaceae is the botanical name for a family of flowering plants. Such a family has been recognized by most taxonomists: it is sometimes known as the "pepper family"....	epiphyte	Peperomia Peperomia *Peperomia* is one of the 2 large genus of the Piperaceae family , with more than 1000 recorded species. Most of them are compact, small perennial plant epiphytes growing on rotten wood....
	eudicots	Caryophyllales Caryophyllales Caryophyllales is an Order of flowering plants that includes the cactus, Dianthus caryophylluss, amaranths, ice plants, and most carnivorous plants....	Plantaginaceae Plantaginaceae The Plantaginaceae Juss. or plantain family, is a family of flowering plants in the order Lamiales. The type genus is Plantago Carolus Linnaeus....	hydrophyte	Littorella Littorella *Littorella* is a genus of two to three species of aquatic plants. Many plants live their entire lives submersed, and reproduce by stolons, but some are only underwater for part of the year, and flower when they are not underwater.... uniflora
			Aizoaceae Aizoaceae The Family Aizoaceae or Ficoidaceae is a taxon of dicotyledonous flowering plants containing 135 genera and about 1900 species. They are commonly known as stone plants or carpet weeds....	xerophyte	widespread in the family; Mesembryanthemum crystallinum Mesembryanthemum crystallinum *Mesembryanthemum crystallinum* is a prostrate succulent plant that is native to Africa, Western Asia and Europe. The plant is covered with large, glistening bladder cells, reflected in its common names of Common Ice Plant, Crystalline Iceplant or Iceplant.... is a rare instance of an halophyte which displays CAM
			Cactaceae	xerophyte	all cacti have obligate Crassulacean Acid Metabolism in their stems; those few cacti with leaves have C3 Metabolism in those leaves; seedlings have C3 Metabolism.
			Portulacaceae Portulacaceae Portulacaceae is a family of flowering plants, comprising about 20 genera with about 500 species, ranging from herbaceous plants to shrubs. The family has been recognised by most taxonomists, and is also known as the purslane family; it has a cosmopolitan distribution, with the highest diversity in semi-arid regions of the Southern Hemispher...	xerophyte	recorded in approximately half of the genera (note: Portulacaceae is paraphyletic with respect to Cactaceae and Didieraceae)
			Didiereaceae Didiereaceae Didiereaceae is a small family of just four genera and 11 species of flowering plants endemic to south and southwest Madagascar, where they form an important component of the Ecoregions of Madagascar....	xerophyte
		Saxifragales Saxifragales The Saxifragales are an order of dicotyledon flowering plants. In the APG II classification system, it includes the following families:* Family Altingiaceae ...	Crassulaceae Crassulaceae The Crassulaceae, or orpine family, is a family of dicotyledons. They store water in their succulent leaves. They are found worldwide, but mostly occur in the Northern Hemisphere and southern Africa, typically in dry and/or cold areas where water may be scarce....	hydrophyte, xerophyte, lithophyte	CAM is widespread in the family
	eudicots (rosids)	Vitales	Vitaceae Vitaceae Vitaceae are a family of dicotyledonous flowering plants including the grape and Virginia creeper. The family name is derived from the genus Vitis....		Cissus Cissus *Cissus* is a genus of approximately 350 species of woody climber in the grape family . They have a cosmopolitan distribution, though the majority are to be found in the tropics.... , Cyphostemma Cyphostemma *Cyphostemma* is a flowering plant genus belonging to the family Vitaceae. These species are Caudex and used to belong to the genus Cissus....
		Malpighiales Malpighiales The Malpighiales are a large order of flowering plants, included in the group named eurosids I in the recent Angiosperm Phylogeny Group classification....	Clusiaceae Clusiaceae The Clusiaceae or Guttiferae Juss. is a family of plants including about 37 genera and 1610 species of trees and shrubs, often with milky sap and fruits or capsule for seeds....	hemiepiphyte	Clusia Clusia *Clusia* is the type genus of the family Clusiaceae. Comprising 140-150 species, it is native to tropical and subtropical Americas. Its species are shrubs, vines and small to medium-size trees up to 20 m tall, with evergreen foliage....
			Euphorbiaceae Euphorbiaceae The Spurge family is a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees....		CAM is found is some species of Euphorbia including some formerly placed in the sunk genera Monadenium, Pedilanthus and Synadenium. C4 photosynthesis is also found in Euphorbia (subgenus Chamaesyce).
			Passifloraceae Passifloraceae Passifloraceae is a family of flowering plants, containing about 530 species classified in around 18 genera. They include trees, shrubs, lianas and climbing plants, and are mostly found in tropical regions ....	xerophyte	Adenia Adenia *Adenia* is a genus in the passionflower family Passifloraceae....
		Geraniales Geraniales The Geraniales are a small order of flowering plants, included within the rosid subgroup of dicotyledons. The largest family in the order is the Geraniaceae with over 800 species....	Geraniaceae Geraniaceae Geraniaceae is a family of flowering plants placed in the order Geraniales. The family name is derived from the genus Geranium. It includes both the genus cranesbill and the garden plants called geraniums, which modern botany classifies as genus Pelargonium, along with other related genera....		CAM is found in some succulent species of Pelargonium Pelargonium *Pelargonium* is a genus of flowering plants which includes about 200 species of perennial plants, succulent plants, and shrubs, commonly known as geraniums or storksbills.... , and is also reported from Geranium pratense Geranium pratense *Geranium pratense, the Meadow Cranesbill*, is a species of plant in the Geraniaceae family. The leaves are deeply divided, divided into 7-9 lobes and 3-6 inch wide....
		Cucurbitales Cucurbitales The Cucurbitales are an order of flowering plants, included in the rosid group of dicotyledons. This order mostly belongs to tropical areas, with limited presence in subtropic and temperate regions....	Cucurbitaceae Cucurbitaceae Cucurbitaceae is a plant family commonly known as melons, gourds or cucurbits and includes crops like cucumbers, squash , luffas, melons and watermelons....		Xerosicyos Xerosicyos *Xerosicyos* is a flowering plant genus of the family Cucurbitaceae. Its name comes from Greek language xeros and sicyos . They are lianas with succulent leaves.... danguyi, Dendrosicyos socotrana, Momordica Momordica *Momordica* is a genus of about 45 species of annual or perennial climbing herbaceous or shrubby plants belonging to the family Cucurbitaceae, natives of tropical and subtropical Africa and Asia and Australia....
		Celastrales Celastrales The Celastrales are an order of flowering plants, included within the rosid subgroup of dicotyledons. Newer classifications include the following three families:...	Celastraceae Celastraceae The Celastraceae , is a family of about 90-100 genera and 1,300 species of vines, shrubs and small trees, belonging to the order Celastrales. The great majority of the genus are tropical, with only Celastrus , Euonymus and Maytenus widespread in temperate climates....
		Oxalidales Oxalidales The Oxalidales are an order of flowering plants, included within the rosid subgroup of dicotyledons. The following families are typically placed here:...	Oxalidaceae Oxalidaceae The Oxalidaceae, or wood sorrel family, is a small family of eight genera of herbaceous plants, shrubs and small trees, with the great majority of the 900 species in the genus Oxalis ....
		Brassicales Brassicales The Brassicales are an order of flowering plants, belonging to the eurosids II group of dicotyledons under the APG II system. Brassicales sensu APG II includes families classified under Capparales in previous classifications....	Moringaceae		Moringa Moringa Moringa is the only genus in the family Moringaceae. This genus comprises 13 species, all of which are trees that grow in tropical and Subtropics climates....
		Sapindales Sapindales Sapindales is a botanical name for an order of flowering plants. Well-known members of Sapindales include citrus; maples, Horse-chestnut s, lychees and rambutans; mangos and cashews; frankincense and myrrh; and mahogany....	Sapindaceae Sapindaceae Sapindaceae, also known as the soapberry family, is a family of flowering plants in the order Sapindales. There are about 140-150 genera with 1400-2000 species, including maple, Aesculus and lychee....		Dodonaea viscosa Dodonaea viscosa *Dodonaea viscosa* is a species of flowering plant in the Sapindus family, Sapindaceae, that has a cosmopolitan distribution in tropical, subtropical and warm temperate regions of Africa, the Americas, southern Asia and Australasia....
			Zygophyllaceae Zygophyllaceae The Zygophyllaceae, of about 250 species, are a family of flowering plants, also known as the bean-caper or caltrop family.According to the Angiosperm Phylogeny Group , the heterogeneous family Zygophyllaceae is unplaced to order, but included in the Eurosids I as a sister to a clade composed of several orders....		Zygophyllum Zygophyllum *Zygophyllum* is a genus of plant in family Zygophyllaceae. It is distributed in arid and semi-arid regions of Africa, the Mediterranean, central Asia and Australia....
	eudicots (asterids)	Ericales Ericales The Ericales are a large and diverse order of dicotyledons, including for example tea, persimmon, blueberry, Brazil nut, and azalea. The order includes trees and shrubes, lianas and herbaceous plants....	Ebenaceae Ebenaceae The Ebenaceae are a family of flowering plants, which includes ebony and persimmon. The family has approximately 500 species of trees and shrubs in two genus, Diospyros and Euclea....
		Solanales Solanales The Solanales are an order of flowering plants, included in the asterid group of dicotyledons. Some older sources used the name Polemoniales for this order....	Convolvulaceae Convolvulaceae The Convolvulaceae, known commonly as the bindweed or morning glory family , is a group of about 60 genera and more than 1,650 species of mostly herbaceous vines, but also trees, shrubs and herbs....		Ipomaea
		Gentianales Gentianales Gentianales are an order of flowering plants, included within the asterid group of dicotyledons.The circumscription of Gentiales in the Cronquist system included a broadly defined Loganiaceae , Retziaceae, Gentianaceae, Saccifoliaceae, Apocynaceae, and Asclepiadaceae....	Rubiaceae Rubiaceae Rubiaceae is a family of flowering plants, variously called the madder family, bedstraw family or Coffea family. Other common plants included here are gardenia, cinchona, sweet woodruff, Mitchella, uncaria, ixora, and noni....	epiphyte	Hydnophytum and Myrmecodia Myrmecodia *Myrmecodia* is a genus of epiphytic myrmecophytes native to Southeast Asia. Myrmecodia plants grow in tree branches and on trunks. In nature, Myrmecodia tubers often grow hanging downward on bare branches without significant amounts of substrate, and thus depend upon symbiosis for most nutriment....
			Apocynaceae Apocynaceae The Apocynaceae or dogbane family is a family of Angiosperms that includes trees, shrubs, herbs, and lianas.Many species are tall trees found in tropical rainforests, and most are from the tropics and subtropics, but some grow in tropical dry, xeric environments....		CAM is found in subfamily Asclepidioideae (Hoya Hoya *Hoya* is a genus of 200-300 species of tropical climbing plants in the family Apocynaceae , native to southern Asia , Australia, and Polynesia.... , Dischidia Dischidia *Dischidia* is a genus of plants in the Milkweed family, Asclepiadaceae. It comprises about 80 known species which all grow as epiphytes and are native to tropical areas of China, India and most areas of Indo China.... , Ceropegia Ceropegia *Ceropegias* are an interesting group of plants which have attracted much attention from botanists, horticulturalists, gardeners, succulent enthusiasts.... , Stapelia Stapelia The genus *Stapelia* consists of around 40 species of low growing, spineless, stem succulent plants, predominantly from South Africa. The flowers of certain species, most notably Stapelia gigantea, can reach 41 cm in diameter when fully open.... , Caralluma Caralluma *Caralluma* is a genus of plants consisting of about 120 species. Once classified in the family Asclepiadaceae, it is now in the subfamily Asclepiadoideae of the dogbane family Apocynaceae.... negevensis, Frerea indica, Adenium Adenium *Adenium* is a genus of flowering plants in the family Apocynaceae, containing a single species, *Adenium obesum, also known as Sabi Star, Kudu* or Desert-rose.... , Huernia Huernia The genus *Huernia* consists of some 60 species of stem succulents from Eastern and Southern Africa. The flowers are five-lobed, usually somewhat more funnel- or bell-shaped than in the closely related genus Stapelia, and often striped vividly in contrasting colours or tones, some glossy, others matt and wrinkled depending on the specie... ), and also in Carissa Carissa *CarissaMostly referred to a genus of about 20-30 species of shrubs or small trees native to tropical and subtropical regions of Africa, Australia and Hong Kong.... and Akocanthera*
		Lamiales Lamiales The order Lamiales is a taxon in the Asteridae group of dicotyledonous flowering plants. It includes approximately 11,000 species divided up into about 10 family ....	Gesneriaceae Gesneriaceae Gesneriaceae is a family of flowering plants consisting of ca. 150 genera and ca. 3200 species in the Old World and New World tropics and subtropics, with a very small number extending to temperate areas....	epiphyte	CAM was found Codonanthe crassifolia, but not in 3 other genera
			Lamiaceae Lamiaceae Lamiaceae or Labiatae, also known as the mint family, is a family of plants comprising about 210 genera and some 3,500 species. It has been considered closely related to Verbenaceae but several recent phylogenetic studies have shown that numererous genera classified in Verbenaceae belong instead in Lamiaceae, whereas the core genera of...		Plectranthus Plectranthus *Plectranthus* is a genus of warm-climate plants, closely related to Solenostemon, sometimes known as the spurflowers. Several species are grown as ornamental plants, as leaf vegetables, as root vegetables for their edible tubers, or as herbalism.... marrubioides, Coleus Coleus *Solenostemon* is a genus of perennial plants, native to tropical Africa, Asia, Australia, the East Indies, the Malay Archipelago, and the Philippines....
		Apiales Apiales The Apiales are an order of flowering plants. The families given at right are typical of newer classifications, though there is some slight variation, and in particular the Torriceliaceae may be divided....	Apiaceae Apiaceae The Apiaceae or Umbelliferae is a family of usually aromatic plants with hollow stems, commonly known as umbellifers. It includes cumin, parsley, carrot, coriander/cilantro, dill, caraway, fennel, parsnip, celery, Queen anne's lace and other relatives....	hydrophyte	Lilaeopsis Lilaeopsis A genus of about five species known as Grasswort. L. brasiliensis at least is used as a decorative plant for the foreground of aquariums.It contains the following species:... lacustris
		Asterales Asterales The Asterales are an order of dicotyledonous flowering plants which include the composite family Asteraceae and its related families.The order is cosmopolitic, and includes mostly herbaceous species, although a small number of trees and shrubs is also present....	Asteraceae Asteraceae The family Asteraceae or Compositae is the largest family of flowering plants, in terms of number of species.The name 'Asteraceae' is derived from the type genus Aster , while 'Compositae', an older but still valid name, means composite and refers to the characteristic inflorescence, a special type of pseudanthium found in o...		some species of Senecio Senecio *Senecio* is a genus of the daisy family that includes ragworts and groundsels. The flower heads are normally rayed, completely yellow, and the heads are borne in branched clusters....
Magnoliophyta	monocots	Alismatales Alismatales Alismatales is an order of flowering plants. The order will of necessity contain the family Alismataceae....	Hydrocharitaceae Hydrocharitaceae Hydrocharitaceae is a plant family that includes a number of species of aquatic plant, broadly called the Tape-grasses, and includes the well known Canadian Waterweed and Frog's Bit....	hydrophyte	Hydrilla Hydrilla *Hydrilla* is an aquatic plant genus, usually treated as containing just one species, *Hydrilla verticillata, though some botanists divide it into several species.... , Vallisneria Vallisneria Vallisneria* is a genus of aquatic plant, commonly called eelgrass, tape grass or vallis. The genus has 6-10 species that are widely distributed, but do not grow in colder regions....
			Alismataceae Alismataceae The Alismataceae or water-plantain family is a family of flowering plants, comprising 11 genera and between 85-95 species. The family has a cosmopolitan distribution, with the greatest number of species in temperate regions of the Northern Hemisphere....		Sagittaria Sagittaria *Sagittaria* or "arrowhead" is a genus of about 20 species of aquatic plants whose members go by a variety of common names, including arrowhead, duck potato, iz-ze-kn, katniss, kuwai , swan potato, tule potato, and wapato ....
			Araceae Araceae Araceae is a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe or leaf-like hood....		Zamioculcas Zamioculcas *Zamioculcas* is a genus of flowering plant in the family Araceae, containing the single species *Zamioculcas zamiifolia*. It is a tropical perennial plant native to eastern Africa, from Kenya south to northeastern South Africa.... zamiifolia is the only CAM plant in Araceae, and the only non-aquatic CAM plant in Alismatales
		Poales Poales Poales is a large order of flowering plants in the monocotyledons, and includes families of plants such as the Poaceae, bromeliads, and Cyperaceaes....	Bromeliaceae Bromeliaceae Bromeliaceae is a Family of monocot flowering plants of around 2,400 species native mainly to the Tropics Americas, with a few species found in the American subtropics and one in tropical west Africa....	epiphyte	Bromelioideae (91%), Puya Puya Puya can refer to:* Puya , in the family Bromeliaceae* Puya , a Latin-influenced nu metal band from Puerto Rico* Culoepuya, Venezuelan drums of Congolese origin... (24%), Dyckia Dyckia Dyckia is a genus in the Bromeliaceae family.Species* Dyckia odorata L.B.Smith* Dyckia platyphylla* Dyckia remotiflora... and related genera (all), Hechtia Hechtia Hechtia is a plant genus, containing around fifty species, and named after Julius Gottfried Conrad Hecht. They are dioecious bromeliads, like the pineapple.... (all), Tillandsia Tillandsia The plant genus *Tillandsia*, a member of the Bromeliad family , is found in the deserts, forests and mountains of Central America and South America, and Mexico and the southern United States in North America.... (many)
			Cyperaceae Cyperaceae The family Cyperaceae, or the sedges, is a taxon of monocotyledon flowering plants that superficially resemble Poaceae or Juncaceae. The family is large, with some 4,000 species described in about 70 genera....	hydrophyte	Scirpus Scirpus The plant genus *Scirpus* consists of a large number of aquatic, grass-like species in the family Cyperaceae , many with the common names club-rush or bulrush .... , Eleocharis Eleocharis *Eleocharis* is a genus of 250 or more species the Cyperaceae . They are known commonly as spikerushes, although spikesedges is a more technically appropriate name and most scientists who study them in earnest refer to them as such....
		Asparagales Asparagales Asparagales is an order of flowering plants. The order must include the family Asparagaceae, but other families included in the order have varied markedly between different classifications....	Orchidaceae Orchidaceae Orchidaceae is the largest Family of the flowering plants . Its name is derived from the genus Orchis.The Royal Botanic Gardens, Kew list 880 genus and nearly 22,000 accepted species, but the exact number is unknown because of taxonomic disputes....	epiphyte
			Agavaceae Agavaceae Agavaceae is a family of plants that includes many well-known desert and dry zone types such as the agave, yucca, and Yucca brevifolia. The family includes about 550-600 species in around 18 genus, and is widespread in the tropical, subtropical and warm temperate regions of the world....	xerophyte	Agave Agave Agave is a succulent plant plant of a large botanical genus of the same name, belonging to the family Agavaceae.... , Hesperaloe Hesperaloe *Hesperaloe* is a genus of perennial yucca-like plants classified in the flowering plant family Agavaceae . The plants have long, narrow leaves produced in a basal rosette and flowers borne on long panicles or racemes.... , Yucca Yucca The yuccas comprise the genus *Yucca* of 40-50 species of perennial plants, shrubs, and trees in the agave family Agavaceae, notable for their rosettes of evergreen, tough, sword-shaped Leaf and large terminal clusters of white or whitish flowers....
			Asphodelaceae Asphodelaceae Asphodelaceae is the botanical name of a family of flowering plants. Not all taxonomists recognize Asphodelaceae as a family and the wiktionary:circumscription of the family has varied over time....	xerophyte	Aloe Aloe *Aloe, also written Alo?, is a genus containing about four hundred species of flowering plants succulent plant plants. The most common and well known of these is aloe vera barbadensis miller, or "true aloe".... , Gasteria Gasteria Gasteria* is a genus of succulent plants native to South Africa. Closely-related genera include Aloe and Haworthia. The genus is named for its stomach-shaped flowers and is part of an expanded Asphodelaceae family.... and Haworthia Haworthia Haworthia is a genus of flowering plants within the family Asphodelaceae. They are small solitary or clump-forming and endemic to South Africa....
			Ruscaceae Ruscaceae Ruscaceae is a family of flowering plants in the order Asparagales that includes several genera previously included in the Liliaceae, for example in the Cronquist system....		Sansevieria Sansevieria *Sansevieria* whose common names include: mother-in-law's tongue, devil's tongue, and snake plant, is a genus of about 70 species of flowering plants in the family Ruscaceae, native to tropical and subtropical regions of the Old World.... , Dracaena Dracaena Dracaena can mean:Dracaena , a genus of plantsDracaena , a genus of lizard*Dracena, a town in Brazil...
		Commelinales Commelinales Commelinales is the botanical name of an order of flowering plants. It's considered that the Commelinales together with Zingiberales evolved in the Late Cretaceous around 80 millions of years ago....	Commelinaceae Commelinaceae Commelinaceae is a botanical name for a family of flowering plants, also known as the spiderwort family. The family has always been recognized by most taxonomists....		Callisia Callisia *Callisia, commonly known as Roseling, is a genus in the family Commelinaceae.References ... , Tradescantia Tradescantia Tradescantia* is a genus of an estimated 71 species of perennial plants in the family Commelinaceae, native to the New World from southern Canada south to northern Argentina.... , Tripogandra

Crassulacean acid metabolism

Historical background

Overview of CAM: a two-part cycle

During the night

The next day...

The benefits of CAM

Comparison with metabolism

How to spot a CAM plant

Biochemistry of Crassulacean Acid Metabolism

Ecological and Taxonomic Distribution of CAM Plants

See also