Carnivorous plant 113678 225513741 2008-07-14T02:21:50Z Rkitko 536375 /* Further reading */ going ahead and removing {{feeding}} nav template; doesn't apply to plants [[Image:Palau pitcher plant.jpg|thumb|200px|right|''[[Nepenthes mirabilis]]'' in flower, growing on a road cut in [[Palau]]]] '''Carnivorous plants''' (sometimes called '''insectivorous plants''') are [[plant]]s that derive some or most of their [[nutrient]]s (but not [[energy]]) from trapping and consuming [[animal]]s or [[protozoans]], typically [[insect]]s and other [[arthropod]]s. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially [[nitrogen]], such as acidic [[bog]]s and rock outcroppings. [[Charles Darwin]] wrote the first well-known treatise on carnivorous plants in 1875.<ref name="darwin1875">{{cite book | author=[[Charles Darwin|Darwin]] C | title=Insectivorous plants | publisher=John Murray | location=London | year=1875 | url=http://pages.britishlibrary.net/charles.darwin3/insectivorous/insect01.htm}}</ref> True carnivory is thought to have evolved in at least 10 separate lineages of plants, and these are now represented by more than a dozen [[genus|genera]] in 5 families. These include about 625 species that attract and trap prey, produce digestive enzymes, and absorb the resulting available nutrients. Additionally, over 300 [[protocarnivorous plant]] species in several genera show some but not all these characteristics. ==Trapping mechanisms== [[Image:H chimantensis2.jpg|thumb|The primitive pitchers of ''[[Heliamphora chimantensis]]'' are an example of pitfall traps.]] Five basic trapping mechanisms are found in carnivorous plants. #Pitfall traps ([[pitcher plant]]s) trap prey in a rolled leaf that contains a pool of digestive enzymes or [[bacteria]]. #Flypaper traps use a sticky [[mucilage]]. #Snap traps utilize [[thigmonasty|rapid leaf movements]]. #Bladder traps suck in prey with a bladder that generates an internal [[vacuum]]. #[[Lobster trap|Lobster-pot]] traps force prey to move towards a digestive organ with inward pointing [[trichome|hairs]]. 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, [[sundew]]s are active flypapers whose leaves undergo rapid growth, aiding in the retention and digestion of prey. ===Pitfall traps=== {{main|Pitcher plant}} Pitfall traps are thought to have evolved independently on at least four occasions. The simplest ones are probably those of ''[[Heliamphora]]'', the sun [[pitcher plant]]. In this [[genus]], the traps are clearly derived [[evolution]]arily 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. ''Heliamphora'' is a member of the [[Sarraceniaceae]], a [[New World]] family in the order [[Ericales]] ([[heather]]s and allies). ''Heliamphora'' is limited to South America, but the family contains two other genera, ''[[Sarracenia]]'' and ''[[Darlingtonia (Sarraceniaceae)|Darlingtonia]]'', which are endemic to the [[Southeastern United States]] (with the exception of one species) and [[California]] respectively. ''S. purpurea'' subsp. ''purpurea'' ([[purple pitcher plant|the northern pitcher plant]]) has a more [[cosmopolitan distribution]], found as far north as [[Canada]]. ''Sarracenia'' is the pitcher plant genus most commonly encountered in cultivation, because it is relatively hardy and easy to grow. [[Image:Darlingtonia californica ne8.JPG|thumb|220px|left|''[[Darlingtonia (Sarraceniaceae)|Darlingtonia californica]]'': note the small entrance to the trap underneath the swollen 'balloon', and the colourless patches that confuse prey trapped inside.]] In the genus ''Sarracenia'', the problem of pitcher overflow is solved by an [[Operculum (botany)|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 [[protease]]s and [[phosphatase]]s into the digestive fluid at the bottom of the pitcher; ''Heliamphora'' relies on bacterial digestion alone. The enzymes digest the [[protein]]s and [[nucleic acid]]s in the prey, releasing [[amino acid]]s and [[phosphate]] ions, which the plant absorbs. ''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 [[areola]]e, [[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]]. [[Image:Brocchinea.jpg|thumb|''[[Brocchinia reducta]]'': a carnivorous bromeliad]] The second major group of pitcher plants are the [[monkey cup]]s 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, particularly ''[[Nepenthes rajah|N. rajah]]'', also occasionally take small [[mammal]]s and [[reptile]]s. These pitchers represent a convenient source of food to small insectivores. ''N. bicalcarata'' possesses two sharp thorns that project from the base of the operculum over the entrance to the pitcher, providing some protection from raids by freeloading mammals.{{Fact|date=November 2007}} 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. The lining of most pitcher plants is covered in a loose coating of [[wax]]y flakes, which are slippery for insects, prey that are often attracted by nectar bribes secreted by the peristome, and by bright flower-like [[anthocyanin]] patterning. In at least one species, ''Sarracenia flava'', the nectar bribe is laced with [[coniine]], a toxic [[alkaloid]] also found in [[Conium|hemlock]], which probably increases the efficiency of the traps by intoxicating prey.{{Fact|date=November 2007}} 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 [[habitat (ecology)|habitats]] for [[frog]]s, [[insect]]s and more usefully for plant, [[diazotroph]]ic (nitrogen-fixing) [[bacterium|bacteria]]. In ''Brocchinia'', the urn is a specialised insect trap, with a loose, waxy lining and a population of digestive bacteria.{{Fact|date=November 2007}} ===Flypaper traps=== The flypaper trap is based on a sticky mucilage, or glue. The leaf of flypaper traps is studded with [[mucilage]]-secreting glands, which may be short and nondescript (like those of the [[butterwort]]s), or long and mobile (like those of many [[sundew]]s). Flypapers have evolved independently at least five times. [[Image:Pinguicula gigantea ne.jpg|thumb|''[[Pinguicula gigantea]]'' with prey. The insect was too large and was able to escape.]] In the genus ''[[Pinguicula]]'', the mucilage glands are quite short ([[sessile]]), and the leaf, whilst 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 gnat]]s), and whose surface responds to prey by relatively rapid growth. This [[thigmotropism|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. [[Image:Drosera capensis bend.JPG|thumb|left|160px|The leaf of a ''[[Drosera capensis]]'' "bending" in response to the trapping of an insect.]] The [[sundew]] genus (''[[Drosera]]'') consists of over 100 species of active flypapers, whose mucilage glands are borne at the end of long [[tentacle]]s, 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 [[Antarctica|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 [[estivation|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. Closely related to ''[[Drosera]]'' is the [[Portugal|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 plant|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. Recent molecular data (particularly the production of [[plumbagin]]) indicate that the remaining [[flypaper]], ''[[Triphyophyllum|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. ===Snap traps=== [[Image:VFT ne1.JPG|thumb|The snap traps of ''[[Venus flytrap|Dionaea muscipula]]'' close rapidly when triggered to trap prey between two lobes.]] The only two active snap traps – the [[Venus flytrap]] (''[[Dionaea muscipula]]'') and the [[Aldrovanda vesiculosa|waterwheel plant]] (''[[Aldrovanda]] vesiculosa'') – are believed to have had a [[common ancestor]] with similar adaptations. Their trapping mechanism has also been described as a 'mouse trap' or 'man trap', based on their shape or 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 specialised in catching small invertebrates; ''Dionaea'' is terrestrial and catches a variety of arthropods, including spiders.<ref>''[http://www.sciencenews.org/articles/20050326/timeline.asp Famous Insect Eating Plant Catches Many Spiders]'', The Science Newsletter, [[March 23]], [[1935]], issue</ref> The traps are very similar, with leaves whose terminal section is divided into two lobes, hinged along the midrib. [[Trigger hair]]s (three on each lobe in ''Dionaea'', many more in the case of ''Aldrovanda'') inside the trap lobes are sensitive to touch. When the trigger hairs are bent, stretch-gated [[ion channel]]s in the [[cell membrane|membrane]]s of cells at the base of the trigger hair open, generating an [[action potential]] that propagates to cells in the midrib.<ref name="hodick1989">{{cite journal | author=Hodick D, Sievers A | title=The action potential of ''Dionaea muscipula'' Ellis | journal=[[Planta]] | volume=174 | year=1989 | pages=8–18 | url = http://www.springerlink.com/index/KL80VV1327508844.pdf | doi = 10.1007/BF00394867 }}</ref> 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]].<ref name="hodick1988">{{cite journal | author=Hodick D, Sievers A | title=On the mechanism of closure of Venus flytrap (''Dionaea muscipula'' Ellis) | journal=Planta | volume=179 | year=1988 | pages=32–42 | url = http://www.springerlink.com/index/QPK061437U675H10.pdf | doi = 10.1007/BF00395768 }}</ref> 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,<ref name="hodick1989" /> flipping rapidly from convex to concave<ref name="forterre2005">{{cite journal | author=Forterre Y, Skotheim JM, Dumais J, Mahadevan L | title=How the Venus flytrap snaps | journal=[[Nature (journal)|Nature]] | volume=433 | issue=7024 | year=2005 | pages=421–5 | url = http://www.nature.com/nature/journal/v433/n7024/abs/nature03185.html | doi = 10.1038/nature03185 }}</ref> and interring the prey. This whole process takes less than a second. In the Venus flytrap, spurious closure in response to raindrops and blown-in debris is prevented by the leaves having a simple memory: for the lobes to shut, two [[stimulus (physiology)|stimuli]] are required, 0.5 to 30 seconds apart. 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 grow together towards the prey ([[thigmotropism]]), sealing the lobes [[Hermetic seal|hermetically]], and forming a [[stomach]] in which digestion occurs over a period of one to two weeks. Leaves can be reused three or four times before they become unresponsive to stimulation. ===Bladder traps=== [[Image:Uk pond bladderwort2.jpg|thumb|The tip of one stolon of ''[[Utricularia vulgaris]]'', showing stolon, branching leaf-shoots, and transparent bladder traps.]] [[Image:Genlisea violacea giant.jpg|thumb|''[[Genlisea violacea]]'' traps and leaves.]] Bladder traps are exclusive to the genus ''Utricularia'', or [[bladderwort]]s. The bladders ([[vesiculum|vesicula]]) pump [[ion]]s 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 plant|terrestrial]], growing on waterlogged soil, and their trapping mechanism is triggered in a slightly different manner. Bladderworts lack [[root]]s, but terrestrial species have anchoring stems that resemble them. Temperate aquatic bladderworts generally die back to a resting [[turion (botany)|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. ===Lobster-pot traps=== 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. Outside of ''Genlisea'', features reminiscent of lobster-pot traps can be seen in ''[[Sarracenia psittacina]]'', ''[[Darlingtonia californica]]'', and, some horticulturalists argue, ''[[Nepenthes aristolochioides]]''. ===Borderline carnivores=== {{main|Protocarnivorous plant}} To be a fully fledged carnivore, a plant must attract, kill, and [[digestion|digest]] [[prey]];<ref name="Juniper1989">{{cite book |last= Juniper |first= B. E. |coauthors= Robbins, R.J., and Joel, D.M. |title= The Carnivorous Plants |publisher= Academic Press |year= 1989 |isbn= 0-1239-2170-8 }}</ref><ref name="Albert1992">{{cite journal | author=Albert, V.A., Williams, S.E., and Chase, M.W. | title=Carnivorous plants: Phylogeny and structural evolution | journal=[[Science (journal)|Science]] | volume=257 | year=1992 | pages=1491–1495 | doi=10.1126/science.1523408 | pmid=1523408 }}</ref> and it must benefit from absorbing the products of the digestion (mostly [[amino acid]]s and [[ammonium]] ions).<ref name="givnish1984" /> To many horticulturalists, these distinctions are a matter of taste. There is a spectrum of carnivory found in plants: from completely non-carnivorous plants like [[cabbage]]s, to borderline carnivores, to unspecialised and simple traps, like ''Heliamphora'', to extremely specialised and complex traps, like that of the Venus flytrap. [[Image:Roridula gorgonias.jpg|thumb|200px|left|''[[Roridula|Roridula gorgonias]]'': a borderline carnivore that gains nutrients from its 'prey' ''via'' the droppings of a predatory bug]] The borderline carnivores include ''[[Roridula]]'' and ''[[Catopsis berteroniana]]''. ''Catopsis'' is a borderline carnivorous bromeliad, like ''[[Brocchinia reducta]]''. However, unlike the [[phosphatase]] of ''B. reducta'', ''C. berteroniana'' has not been shown to produce digestive enzymes.<ref name="Plachno2005">{{cite conference | first = B.J. | last = Plachno | coauthors = Jankun, A. | title = Phosphatase activity in glandular structures of carnivorous plant traps | pages = 1716 | booktitle = Proc. of the International Botanical Congress | date = 2005 | location = The Jagiellonian University, Krakow, Poland }}</ref> In these pitfall traps, prey simply fall into the urn, assisted by the waxy scales located on the rim. ''Roridula'' has a more intricate relationship with its prey. 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 [[mutualism|mutualistic]] [[symbiosis]] with species of [[assassin bug]] (genus ''[[Pameridea]]''), which eat the trapped insects. The plant benefits from the nutrients in the bugs' [[feces|faeces]].<ref name="Hartmeyer1998">{{cite journal | author=Hartmeyer, S. | title=Carnivory in ''Byblis'' revisited II: The phenomenon of symbiosis on insect trapping plants | journal=Carnivorous Plant Newsletter | volume=27 | issue=4 | year=1998 | pages=110–113 | url=http://www.carnivorousplants.org/cpn/samples/Science274Byblis2.htm }}</ref> 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.<ref name="Schnell2002">{{cite book |last= Schnell |first= Donald E. |title= Carnivorous plants of the United States and Canada |publisher= Timber Press |year= 2002 |isbn= 0-88192-540-3 }}</ref> Likewise, the seeds of [[Shepherd's Purse]],<ref name="Schnell2002" /> urns of ''[[Paepalanthus bromelioides]]'',<ref name="Rice2006">{{cite book |last= Rice |first= Barry A. |title= Growing Carnivorous Plants |publisher= Timber Press |year= 2006 |isbn= 0-88192-807-0 }}</ref> bracts of ''[[Passiflora foetida]]'',<ref name="Radhamani1995">{{cite journal | author= Radhamani, T.R., Sudarshana, L., and Krishnan, R. | title=Defence and carnivory: Dual role of bracts in ''Passiflora foetida'' | journal=Journal of Biosciences | volume=20 | issue=5 | year=1995 | pages=657–664 | url=http://medind.nic.in/imvw/imvw14993.html | doi= 10.1007/BF02703305}}</ref> and flower stalks and sepals of [[triggerplants]] (''Stylidium'')<ref name="Darnowski2006">{{cite journal | author= Darnowski, D.W., Carroll, D.M., Płachno, B., Kabanoff, E., and Cinnamon, E. | title=Evidence of protocarnivory in triggerplants (''Stylidium'' spp.; Stylidiaceae) | journal=Plant Biology (Stuttgart) | volume=8 | issue=6 | year=2006 | pages=805–812 | url=http://www.thieme-connect.com/ejournals/abstract/plantbiology/doi/10.1055/s-2006-924472 | doi= 10.1055/s-2006-924472 <!--Retrieved from URL by DOI bot-->}}</ref> appear to trap and kill insects, but their classification as carnivores is contentious. The production of specific prey-digesting enzymes ([[protease]]s, [[ribonuclease]]s, [[phosphatase]]s, ''etc.''), is sometimes used as a criterion for carnivory. However, this would probably discount ''Heliamphora'',<ref name="">{{cite journal | author= Jaffe, K., Michelangeli, F., Gonzalez, J.M., Miras, B., and Ruiz, M.C. | title=Carnivory in pitcher plants of the genus ''Heliamphora'' (Sarraceniaceae) | journal=New Phytologist | volume=122 | issue=4 | year=1992 | pages=733–744 | url=http://links.jstor.org/sici?sici=0028-646X%28199212%29122%3A4%3C733%3ACIPPOT%3E2.0.CO%3B2-K&size=LARGE }}</ref> and ''Darlingtonia'',<ref name="Ellison2005">{{cite journal | author= Ellison, A.M. and Farnsworth, E.J. | title=The cost of carnivory for ''Darlingtonia californica'' (Sarraceniaceae): Evidence from relationships among leaf traits | journal=[[American Journal of Botany]] | volume=92 | issue=7 | year=2005 | pages=1085–1093 | doi=10.3732/ajb.92.7.1085 }}</ref> all of which appear to rely on the enzymes of [[symbiotic]] [[bacterium|bacteria]] to break down their prey, but are generally considered as carnivores. However, discounting the enzyme-based definition leaves open the question of ''Roridula''. There is no reason why a plant's possession of symbiotic bacteria that allow it to benefit from trapped prey should allow the plant to be considered carnivorous, whilst possession of symbiotic bugs should not. ==Evolution== [[Image:Archaeamphora longicervia.png|thumb|Artist's restoration of ''[[Archaeamphora longicervia]]'', the earliest known carnivorous plant.]] The evolution of carnivorous plants is obscured by the paucity of their [[fossil record]]. Very few [[fossil]]s have been found, and then usually only as [[seed]] or [[pollen]]. Carnivorous plants are generally herbs and their traps [[primary growth]]. They generally do not form readily fossilisable structures such as thick bark or wood. The traps themselves would probably not be preserved in any case. Still, much can be deduced from the structure of current traps. Pitfall traps are quite clearly derived from rolled leaves. 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 tissue|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'',<ref name="cameron2002">{{cite journal | author=Cameron K, Wurdack KJ, Jobson RW | title=Molecular evidence for the common origin of snap-traps among carnivorous plants | journal=[[American Journal of Botany]] | volume=89 | year=2002 | pages=1503–1509 | url = | doi=10.3732/ajb.89.9.1503 }}</ref> but the traps are so dissimilar that the theory of their origin -- very fast-moving flypapers became less reliant on glue -- remains rather speculative. There are over a quarter of a million species of [[flowering plant]]s. Of these, only around five hundred are known to be carnivorous. True carnivory has probably evolved independently at least ten times; however, some of these 'independent' groups probably descended from a recent common ancestor with a predisposition to carnivory. Some groups (the [[Ericales]] and [[Caryophyllales]]) seem particularly fertile ground for carnivorous [[preadaptation]], although in the former case, this may be more to do with the [[ecology]] of the group than its [[Morphology (biology)|morphology]], as most of the members of this group grow in low-nutrient habitats such as [[heath]] and [[bog]]. It has been suggested that all trap types are modifications of a similar basic structure - the hairy leaf.<ref name="Slack1988">{{cite book | author=Slack A | title=Carnivorous plants | publisher=Alphabooks | location=London | year=1988 | pages=18-19 | isbn= ISBN 0-7136-3079-5 }}</ref> 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 [[suffocation|suffocate]]. Bacteria jumpstart [[decay]], releasing from the [[Dead body|corpse]] nutrients that the plant can absorb through its leaves. This [[foliar feeding]] can be observed in most non-carnivorous plants. Plants that were better at retaining insects or water therefore had a selective advantage. Rainwater can be retained by cupping the leaf, leading to pitfall traps. Alternatively, insects can be retained by making the leaf stickier by the production of [[mucilage]], leading to flypaper traps. The 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, except at the bottom, where they help retain prey. The lobsterpot 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 lobsterpot is an adaptation that displays as much trapping surface as possible in all directions when buried in [[moss]]. [[Image:CatopsisBerteroniana AtSierraDeLema4836.jpg|thumb|The traps of ''[[Catopsis berteroniana]]'' are unlikely to have descended from a hairy leaf or sepal.]] 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. Flypaper traps include the various true flypapers and the snap traps of ''Aldrovanda'' and ''Dionaea''. The production of sticky mucilage is found in many non-carnivorous genera, and the passive glue traps in ''Byblis'' and ''Drosophyllum'' could easily have evolved. The active glue traps use [[rapid plant movement]]s 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, but the Venus flytrap uses such rapid turgor changes that glue became unnecessary. The stalked glands that once made it and which are so evident in ''Drosera'' have become the teeth and trigger hairs - an example of natural selection [[preadaptation|hijacking preexisting structures ]]for new functions. Recent taxonomic analysis<ref name="cameron1995">{{cite journal | author=Cameron KM, Chase MW, Swensen SM | title=Molecular evidence for the relationships of ''Triphyophyllum'' and ''Ancistrocladus'' | journal=[[American Journal of Botany]] | volume=82 | issue=6 | year=1995 | pages=117–118 | url=http://www.jstor.org/view/03636445/di001110/00p0305w/0 | format={{dead link|date=June 2008}} &ndash; <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=intitle%3AMolecular+evidence+for+the+relationships+of+%27%27Triphyophyllum%27%27+and+%27%27Ancistrocladus%27%27&as_publication=%5B%5BAmerican+Journal+of+Botany%5D%5D&as_ylo=1995&as_yhi=1995&btnG=Search Scholar search]</sup> }} [http://www.carnivorousplants.org/cpn/samples/Science262Evol.htm Discussion of this paper] at the International carnivorous plant society website (original paper requires JSTOR subscription).</ref> of the relationships within the [[Caryophyllales]] indicate that the [[Droseraceae]], ''[[Triphyophyllum]]'', [[Nepenthaceae]] and ''Drosophyllum'', whilst closely related, are embedded within a larger [[cladistics|clade]] that includes non-carnivorous groups such as the [[Tamarix|tamarisks]], [[Ancistrocladaceae]], [[Polygonaceae]] and [[Plumbaginaceae]]. Interestingly, 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 chemical, such as proteases and mucilage. Some of the Plumbaginaceae (''e.g.'' ''Ceratostigma'') also have stalked, vascularised glands that secrete mucilage on their [[calyx (botany)|calyces]] and aid in seed dispersal and possibly in protecting the flowers from crawling parasitic insects. These are probably homologous with the tentacles of the carnivorous genera. Perhaps carnivory evolved from a protective function, rather than a nutritional one. The balsams (such as ''[[Impatiens]]''), which are closely related to the [[Sarraceniaceae]] and ''[[Roridula]]'' similarly possess stalked glands. 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 fundamental part of a bromeliad - for a new purpose, and build on it by the production of wax and the other paraphernalia of carnivory. ==Ecology and modelling of carnivory== Carnivorous plants are widespread but rather rare. They are almost entirely restricted to [[habitat (ecology)|habitats]] such as [[bog]]s, where soil nutrients are extremely limiting, but where [[sun]]light and water are readily available. Only under such extreme conditions is carnivory favoured to an extent that makes the adaptations obvious. The [[archetype|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 for [[chlorophyll]] synthesis. The soil is often [[waterlogging|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. [[Image:Dros2.jpg|thumb|250px|''[[Drosophyllum lusitanicum]]'' is one of the few carnivorous plants to grow in dry, alkaline soil.]] 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.<ref name="zamora1997">{{cite journal | author=Zamora R, Gomez JM, Hodar JA | title=Responses of a carnivorous plant to prey and inorganic nutrients in a Mediterranean environment | journal=[[Oecologia]] | volume=111 | year=1997 | pages=443–451 | doi=10.1007/s004420050257 }}</ref> In all the studied cases, carnivory allows plants to grow and reproduce using animals as a source of nitrogen, phosphorus and possibly potassium.<ref name="thoren1998">{{cite journal | author=Thoren LM, Karlsson PS | title=Effects of supplementary feeding on growth and reproduction of three carnivorous plant species in a subarctic environment | journal=[[Journal of Ecology]] | volume=86 | year=1998 | pages=501–510 | doi=10.1046/j.1365-2745.1998.00276.x }}</ref><ref name="hanslin1996">{{cite journal | author=Hanslin HM, Karlsson PS | title=Nitrogen uptake from prey and substrate as affected by prey capture level and plant reproductive status in four carnivorous plant species | journal=[[Oecologia]] | volume=106 | year=1996 | pages=370–375 | doi=10.1007/BF00334564 }}</ref><ref name="deridder1992">{{cite journal | author=Deridder F, Dhondt AA | title=A positive correlation between naturally captured prey, growth and flowering in ''Drosera intermedia'' in two contrasting habitats | journal=[[Belgian Journal of Botany]] | volume=125 | year=1992 | pages=30–44 }}</ref> 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).<ref name="karlsson1992">{{cite journal | author=Karlsson PS, Pate JS | title=Contrasting effects of supplementary feeding of insects or mineral nutrients on the growth and nitrogen and phosphorus economy of pygmy species of ''Drosera'' | journal=[[Oecologia]] | volume=92 | year=1992 | pages=8–13 | doi=10.1007/BF00317256 }}</ref> Common butterworts (''Pinguicula vulgaris'') can use inorganic sources of nitrogen better than organic sources, but a mixture of both is preferred.<ref name="thoren1998" /> European bladderworts seem to use both sources equally well. Animal prey makes up for differing deficiencies in soil nutrients. Plants use their leaves to intercept sunlight. The energy is used to reduce carbon dioxide from the air with [[electron]]s from water, to make sugars (and other [[biomass]]), and a waste product, [[oxygen]], in the process of [[photosynthesis]]. Leaves also [[Cellular respiration|respire]], in a similar way to animals, by burning their biomass to generate chemical energy. This energy is temporarily stored in the form of [[Adenosine triphosphate|ATP]] ([[adenosine]] triphosphate), which acts as an energy currency for metabolism in all living things. As a waste product, respiration produces [[carbon dioxide]]. 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.<ref name="givnish1984">{{cite journal | author=Givnish TJ, Burkhardt EL, Happel RE, Weintraub JD | title=Carnivory in the bromeliad ''Brocchinia reducta'', with a cost-benefit model for the general restriction of carnivorous plants to sunny, moist, nutrient-poor habitats | journal=[[American Naturalist]] | volume=124 | year=1984 | pages=479–497 | url=http://www.jstor.org/view/00030147/di006263/00p0048e/0 | doi=10.1086/284289 | format={{dead link|date=June 2008}} &ndash; <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=intitle%3ACarnivory+in+the+bromeliad+%27%27Brocchinia+reducta%27%27%2C+with+a+cost-benefit+model+for+the+general+restriction+of+carnivorous+plants+to+sunny%2C+moist%2C+nutrient-poor+habitats&as_publication=%5B%5BAmerican+Naturalist%5D%5D&as_ylo=1984&as_yhi=1984&btnG=Search Scholar search]</sup> }} (Requires JSTOR subscription)</ref> 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.<ref name="Gallie1997">{{cite journal | author=Gallie, D. R. & Chang, S. C. | title=Signal transduction in the carnivorous plant ''Sarracenia purpurea'' - regulation of secretory hydrolase expression during development and in response to resources | journal=[[Plant Physiology (journal)|Plant Physiology]]| volume=115 | year=1997 | pages=1461–1471 | doi=10.1104/pp.115.4.1461 }}</ref> 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. 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. It is intuitively clear that the Venus flytrap is more carnivorous than ''Triphyophyllum peltatum''. The former is a full-time moving snap-trap, the second 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. [[Image:Carnivorous plant model 1.png|thumb|400px|center|Modelling carnivory in plants: gross photosynthesis, respiration and net photosynthesis as a function of the plant's investment in carnivorous adaptations. Non-zero optimum carnivory occurs in brightly lit habitats with very limiting soil nutrients.]] Using this measure of investment in carnivory, a model can be proposed.<ref name="givnish1984" /> 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 [[Optimization (mathematics)|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 [[cyanobacterium|cyanobacteria]]. [[Image:Carnivorous plant model 2.png|thumb|400px|center|Modelling carnivory in plants: gross photosynthesis, respiration and net photosynthesis as a function of the plant's investment in carnivorous adaptations. An optimum carnivory of zero occurs in poorly lit habitats with abundant soil nutrients.]] 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. 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. 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.<ref name="zamora1988">{{cite journal | author=Zamora R, Gomez JM, Hodar JA | title=Fitness responses of a carnivorous plant in contrasting ecological scenarios | journal=[[Ecology (journal)|Ecology]] | volume=79 | year=1988 | pages=1630–1644 }}</ref> 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 [[cactus|cacti]] are to water. Carnivory only pays off when the nutrient stress is high and where light is abundant.<ref name="brewer2002">{{cite journal | author=Brewer JS | title=Why don't carnivorous pitcher plants compete with non-carnivorous plants for nutrients? | journal=[[Ecology (journal)|Ecology]] | volume=84 | issue=2 | year=2002 | pages=451–462 | url=http://www.esajournals.org/esaonline/?request=get-document&issn=0012-9658&volume=084&issue=02&page=0451 | doi=10.1890/0012-9658(2003)084[0451:WDTCPP]2.0.CO;2 }}</ref> When these conditions are not met, some plants give up carnivory temporarily. ''Sarracenia'' spp. produce flat, non-carnivorous leaves ([[phyllode]]s) 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 prevent them from forming proper pitchers, and again, the plant produces a phyllode instead. [[Image:TriphyophyllumPeltatumTopview.jpg|250px|thumb|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.]] Many other carnivores shut down in some season. Tuberous sundews die back to tubers in the dry season, bladderworts to [[turion (botany)|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 its produces based on the expected density of prey.<ref name="knight1991">{{cite journal | author=Knight SE, Frost TM | title=Bladder control in ''Utricularia macrorhiza'' - lake-specific variation in plant investment in carnivory | journal=[[Ecology (journal)|Ecology]] | volume=72 | year=1991 | pages=728–734 | doi=10.2307/2937212 }}</ref> 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. The more carnivorous a plant is, the more conventional its habitat is likely to be. Venus flytraps live in a very [[stereotype|stereotypical]], and very specialised habitat, whereas less carnivorous plants (''Byblis'', ''Pinguicula'') are found in more 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. 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. 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 [[epiphyte]]s, and most epiphytes grow in partial shade on tree branches. ''Brocchinia reducta'', on the other hand, is a ground dweller. ==Classification== {{see also|List of carnivorous plants}} The classification of all [[Angiosperm|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<ref name="Muller2004">{{cite journal | author=Muller K, Borsch T, Legendre L, Porembski S, Theisen I, Barthlott W | title=Evolution of carnivory in Lentibulariaceae and the Lamiales | journal=[[Plant Biology (Stuttgart)]] | volume=6 | year=2004 | pages=477–490 | url=http://www.thieme-connect.com/DOI/DOI?10.1055/s-2004-817909 | doi=10.1055/s-2004-817909 }}</ref>). 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): ===Dicots=== [[Image:StylidiumHabitus.jpg|thumb|''[[Stylidium turbinatum]]'']] [[Image:AldrovandaVesiculosaHabit.jpg|thumb|''[[Aldrovanda vesiculosa]]'']] [[Image:ByblisLinifloraHabitus.JPG|thumb|''[[Byblis liniflora]]'']] [[Image:Cephalotus follicularis001.jpg|thumb|''[[Cephalotus follicularis]]'']] *[[Asterales]] ([[sunflower]] and [[daisy]] order) **[[Stylidiaceae]] ***''[[triggerplant|Stylidium]]'' (trigger plants, a borderline carnivore) *[[Caryophyllales]], ([[carnation]] order) **[[Dioncophyllaceae]] ***''[[Triphyophyllum]]'' (a [[tropics|tropical]] [[liana]]) **[[Drosophyllaceae]] ***''[[Drosophyllum]]'' (Portuguese dewy pine) **[[Droseraceae]] ([[sundew]] family) ***''[[Aldrovanda]]'' (waterwheel plant) ***''[[Dionaea]]'' ([[Venus flytrap]]) ***''[[Drosera]]'' ([[sundew]]s) ***†''[[Droserapollis]]'' ***†''[[Droserapites]]'' ***†''[[Droseridites]]'' ***†''[[Fischeripollis]]'' ***†''[[Palaeoaldrovanda]]'' ***†''[[Saxonipollis]]'' **[[Nepenthaceae]] (tropical pitcher-plant family) ***''[[Nepenthes]]'' (tropical pitcher plants or monkey-cups, including ''[[Anurosperma]]'') *[[Ericales]] ([[heather]] order) **[[Roridulaceae]] ***''[[Roridula]]'' (a borderline carnivore) **[[Sarraceniaceae]] (trumpet pitcher family) ***†''[[Archaeamphora]]'' ***''[[Sarracenia]]'' (North American trumpet pitchers) ***''[[Darlingtonia (Sarraceniaceae)|Darlingtonia]]'' (cobra plant/lily) ***''[[Heliamphora]]'' (sun or marsh pitchers) *[[Lamiales]] ([[mentha|mint]] order) **[[Byblidaceae]] ***''[[Byblis (plant)|Byblis]]'' ([[rainbow]] plants) **[[Lentibulariaceae]] ([[bladderwort]] family) ***''[[Pinguicula]]'' ([[butterwort]]s) ***''[[Genlisea]]'' (corkscrew plant) ***''[[Utricularia]]'' ([[bladderwort]]s, including ''[[Polypompholyx]]'', the fairy aprons or pink petticoats and ''[[Biovularia]]'' an obsolete genus) **[[Martyniaceae]] (all borderline carnivores, related to the [[sesame]] plant) ***''[[Ibicella lutea|Ibicella]]'' *[[Oxalidales]] ([[wood sorrel]] order) **''[[Cephalotus]]'' ([[Albany, Western Australia|Albany]] pitcher plant) ===Monocots=== *[[Poales]] ([[grass]] order) **[[Bromeliaceae]] ([[bromeliad]] or [[pineapple]] family) ***''[[Brocchinia reducta|Brocchinia]]'' (a terrestrial [[bromeliad]]) ***''[[Catopsis berteroniana|Catopsis]]'' (a borderline carnivore) **[[Eriocaulaceae]] ([[pipewort]] family) ***''[[Paepalanthus]]'' (a borderline carnivore) ==Cultivation== [[Image:2005-12-18 N rajah 034.jpg|thumb|Cultivated ''[[Nepenthes rajah]]'' and other species.]] Although different species of carnivorous plants have different requirements in terms of sunlight, humidity, soil moisture, ''etc.'', there are commonalities. Most carnivorous plants require rainwater, or water that has been [[distill]]ed, deionised by [[reverse osmosis]], or acidified to around pH 6.5 using [[sulfuric acid]]. Common tap or drinking water contains minerals (particularly [[calcium]] salts) that will quickly build up and kill the plant. This is because most carnivorous plants have evolved in nutrient-poor, acidic soils and are consequently extreme [[calcifuge]]s. They are therefore very sensitive to excessive soil-borne nutrients. Since most of these plants are found in bogs, almost all are very intolerant of drying. There are exceptions: tuberous sundews require a dry (summer) [[estivation|dormancy]] period, and ''Drosophyllum'' requires much drier conditions than most. Outdoor-grown carnivorous plants generally catch more than enough insects to keep themselves properly fed. Insects may be fed to the plants by hand to supplement their diet; however, carnivorous plants are generally unable to digest large non-insect food items; bits of hamburger, for example, will simply rot, and this may cause the trap, or even the whole plant, to die. A carnivorous plant that catches no insects at all will rarely die, although its growth may be impaired. In general, these plants are best left to their own devices: after underwatering with tap-water, the most common cause of Venus flytrap death is prodding the traps to watch them close and feeding them cheese and other inappropriate items. Most carnivorous plants require bright light, and most will look better under such conditions, as this encourages them to synthesise red and purple [[anthocyanin]] pigments. ''Nepenthes'' and ''Pinguicula'' will do better out of full sun, but most other species are happy in direct sunlight. Carnivores mostly live in bogs, and those that do not are generally tropical. Hence, most require high humidity. On a small scale, this can be achieved by placing the plant in a wide saucer containing pebbles that are kept permanently wet. Small ''Nepenthes'' species grow well in large [[terrarium|terraria]]. Many carnivores are native to cold temperate regions and can be grown outside in a bog garden year-round. Most ''Sarracenia'' can tolerate temperatures well below freezing despite most species being native to the southeastern United States. Species of ''Drosera'' and ''Pinguicula'' also tolerate subfreezing temperatures. ''Nepenthes'' species, which are tropical, require temperatures from 20 to 30 °C to thrive. [[Image:Sarracenia 2.jpg|thumb|left|Many ''[[Sarracenia]]'' hybrids are easy to grow.]] Carnivorous plants require appropriate nutrient-poor soil. Most appreciate a 3:1 mixture of ''[[Sphagnum]]'' peat to sharp horticultural sand ([[coir]] is an acceptable, and more ecofriendly substitute for peat). ''Nepenthes'' will grow in orchid compost, or in pure ''[[Sphagnum]]'' moss. Ironically, carnivorous plants are themselves susceptible to infestation by parasites such as [[aphids]] or [[mealybug]]s. Although small infestations can be removed by hand, larger infestations necessitate use of an [[insecticide]]. [[Isopropyl alcohol]] (rubbing alcohol) is effective as a topical insecticide, particularly on [[scale insect]]s. [[Diazinon]] is an excellent systemic insecticide that is tolerated by most carnivorous plants. [[Malathion]] and [[Acephate]] ([[Orthene]]) have also been reported as tolerable by carnivorous plants. Although insects can be a problem, by far the biggest killer of carnivorous plants (besides human maltreatment) is [[Botrytis cinerea|grey mould]] (''Botrytis cinerea''). This thrives under warm, humid conditions, and can be a real problem in winter. To some extent, temperate carnivorous plants can be protected from this pathogen by ensuring that they are kept cool and well ventilated in winter, and that any dead leaves are removed promptly. If this fails, a [[fungicide]] is in order. The easiest carnivorous plants for beginners are those from the cool temperate zone. These plants will do well under cool greenhouse conditions (minimum 5 °C in winter, maximum 25 °C in summer) if kept in wide trays of acidified or rain water during summer, and kept moist during winter: *''[[Drosera capensis]]'', the Cape sundew: attractive strap-leaved sundew, pink flowers, very tolerant of maltreatment. *''[[Drosera binata]]'', the fork-leaved sundew: large, Y-shaped leaves. *''[[Sarracenia flava]]'', the yellow trumpet pitcher: yellow, attractively veined leaves, yellow flowers in spring. *''[[Pinguicula grandiflora]]'', the common butterwort: purple flowers in spring, hibernates as a bud ([[hibernaculum]]) in winter. Fully hardy. *''[[Pinguicula moranensis]]'', the Mexican butterwort: pink flowers, non-carnivorous leaves in winter. Venus flytraps will do well under these conditions, but are actually rather difficult to grow: even if treated well, they will often succumb to grey mould in winter unless well ventilated. Some of the lowland ''Nepenthes'' are very easy to grow, as long as they are provided with relatively constant, hot and humid conditions. ==Cultural depictions== <!-- ATTENTION! Before adding information to this section, please read and make sure you understand the meaning of [[WP:TRIVIA]]. Trivia sections are discouraged and including "video game, movie, tv show X had carnivorous plants" is not considered encyclopedic. Thanks! --> [[Image:Little Shop of Horrors gore.JPG|left|thumb|Audrey Junior, the man-eating plant from the [[cult film]] ''[[The Little Shop of Horrors]]'']] Carnivorous plants have long been the subject of popular interest and exposition, much of it highly inaccurate. Fictional plants have been featured in a number of books, movies, television series, and video games. Typically, these fictional depictions include exaggerated characteristics, such as enormous size or possession of abilities beyond the realm of reality, and can be viewed as a kind of [[artistic license]]. The most famous examples of fictional carnivorous plants in popular culture include the 1960s [[black comedy]] ''[[The Little Shop of Horrors]]'', the [[triffid]]s of [[John Wyndham (writer)|John Wyndham]]'s ''[[The Day of the Triffids]]'', and others. Other movies and television series utilize accurate depictions of carnivorous plants for cinematic purposes. [[Image:The ya-te-veo.jpg|thumb|Depiction of a native being consumed by a Ya-te-veo ("I can see you") carnivorous tree of Central America, from ''Land and Sea'' by J.W. Buel, 1887.]] The earliest known depiction of carnivorous plants in popular culture was a case where a large [[man-eating tree]] was reported to have consumed a young woman in [[Madagascar]] in 1878, as witnessed by "Dr Carl Liche". Liche reported the events in the ''[[South Australian Register]]'' in 1881. The woman, pictured in an accompanying artwork, was supposed to have been a member of the [[Mkodos]], a 'little known but cruel tribe'. The account has been debunked as pure myth as it appears Dr Liche, the Mkodos, and the tree were all fabrications.<ref>{{cite news|publisher=San Francisco Chronicle|accessdate=2007-10-26|title=The Dirt: Myths about man-eating plants - something to chew on|author=Ron Sullivan and Joe Eaton|date=2007-10-27|url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/10/27/HOIASVF6T.DTL}}</ref> ==See also== *[[Aggressive mimicry]] *[[Carnivorous fungus]] *[[Predatory dinoflagellate]] ==References== {{reflist|2}} ==Further reading== {{commonscat|Carnivorous Plants}} *{{cite book | author=Slack A | title=Insect-eating plants and how to grow them | publisher=Alphabooks | location=Sherborne UK | year=1986 | isbn= ISBN 0-906670-42-X }} *{{cite book | author=Juniper BE, Robins RJ, Joel DM | title=The carnivorous plants | publisher=Academic Press, San Diego | year=1989 }} *[http://www.omnisterra.com/bot/cp_home.cgi Carnivorous Plant Database], provides an up to date, searchable database of all the published species of carnivorous plant *[http://www.sarracenia.com/faq.html Carnivorous Plant FAQ] at Sarracenia.com. *[http://www.sarracenia.com/faq/faq1395.html List of films and TV shows that feature carnivorous plants-most of them fictional] *[http://www.botany.org/carnivorous_plants/ Botanical Society of America - Carnivorous Plants Online] *Ellison, A.M. 2006. {{PDFlink|[http://harvardforest.fas.harvard.edu/publications/pdfs/ellison_PlantBio_2006.pdf Nutrient Limitation and Stoichiometry of Carnivorous Plants.]|334&nbsp;[[Kibibyte|KiB]]<!-- application/pdf, 342725 bytes -->}} ''Plant Biol.'' '''8''': 740–747. {{CarnivorousPlants}} [[Category:Carnivorous plants|*]] [[Category:Plants]] [[Category:Carnivory|Plants]] {{Link FA|it}} <!-- interwiki --> [[ar:نبات لاحم]] [[bs:Biljke mesožderke]] [[bg:Насекомоядно растение]] [[ca:Planta carnívora]] [[cs:Masožravé rostliny]] [[da:Kødædende plante]] [[de:Fleischfressende Pflanzen]] [[es:Planta carnívora]] [[eo:Karnovoraj plantoj]] [[fr:Plante carnivore]] [[gl:Planta carnívora]] [[ko:식충식물]] [[hr:Biljke mesožderke]] [[it:Pianta carnivora]] [[he:צמחים טורפים]] [[lt:Vabzdžiaėdžiai augalai]] [[hu:Húsevő növények]] [[nl:Vleesetende plant]] [[ja:食虫植物]] [[no:Kjøttetende plante]] [[nn:Kjøtetande plante]] [[pl:Roślina mięsożerna]] [[pt:Planta carnívora]] [[ru:Хищные растения]] [[sr:Биљке месождерке]] [[fi:Lihansyöjäkasvi]] [[sv:Köttätande växter]] [[ta:ஊனுண்ணித் தாவரம்]] [[te:కీటకాహార మొక్కలు]] [[uk:Рослини-хижаки]] [[zh:食肉植物]]