| Nepenthes | |
|---|---|
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| Arosette plant ofN. peltata growing onMount Hamiguitan,Mindanao,Philippines | |
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| Nepenthes flowers | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Caryophyllales |
| Family: | Nepenthaceae Dumort.[1] |
| Genus: | Nepenthes L. |
| Type species | |
| Nepenthes distillatoria | |
| Species | |
Seebelow orseparate list. | |
| Diversity[2] | |
| 150+ species | |
| Synonyms[3] | |
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Nepenthes (/nɪˈpɛnθiːz/nih-PEN-theez) is agenus ofcarnivorous plants, also known astropical pitcher plants, ormonkey cups, in themonotypic familyNepenthaceae. The genus includesabout 170 species,[4] and numerousnatural and many cultivated hybrids. They are mostlyliana-forming plants of theOld Worldtropics, ranging from SouthChina,Indonesia,Malaysia, and thePhilippines; westward toMadagascar (two species) and theSeychelles (one); southward toAustralia (four) andNew Caledonia (one); and northward toIndia (one) andSri Lanka (one). Thegreatest diversity occurs onBorneo,Sumatra, and the Philippines, with manyendemic species. Many are plants of hot, humid, lowland areas, but most are tropical,montane plants, receiving warm days but cool to cold, humid nights year-round. A few are considered tropical alpine, with cool days and nights near freezing. The name "monkey cups" refers to the fact thatmonkeys were once thought to drink rainwater from the pitchers.
Nepenthes species usually consist of a shallow root system and aprostrate or climbing stem, often several metres long and up to 15 m (49 ft) or more, and usually 1 cm (0.4 in) or less in diameter, although this may be thicker in a few species (e.g.N. bicalcarata). From the stems arise alternate, sword-shaped leaves with entireleaf margins. An extension of themidrib (thetendril), which in some species aids in climbing, protrudes from the tip of the leaf; at the end of the tendril the pitcher forms. The pitcher starts as a small bud and gradually expands to form a globe- or tube-shaped trap.[5]
The trap contains a fluid of the plant's own production, which may be watery or more viscous, and is used to drown the prey. This fluid containsviscoelasticbiopolymers that may be crucial to the retention of insects within the traps of many species. The viscoelastic fluid in the pitchers is especially effective in the retention of winged insects.[6] The trapping efficiency of this fluid remains high, even when significantly diluted by water, as inevitably happens in wet conditions.[7]
The lower part of the trap contains glands that absorb nutrients from captured prey. Along the upper inside part of the trap is a slick, waxy coating, which makes the escape of its prey nearly impossible. Surrounding the entrance to the trap is a structure called theperistome (the "lip"), which is slippery and often quite colourful, attracting prey, but offering an unsure footing. The prey-capture effectiveness of the peristome is further enhanced in moist environments, where condensation may cause a thin water film to form on the surface of the peristome. When wet, the slippery surface of the peristome causes insects to "aquaplane", or slip and fall, into the pitcher.[8] Above the peristome is a lid (theoperculum); in many species, this keeps rain from diluting the fluid within the pitcher, the underside of which may containnectar glands that attract prey.[5]
Nepenthes species usually produce two types of pitchers, known as leaf dimorphism. Appearing near the base of the plant are the large, lower traps, which typically sit on the ground. The upper or aerial pitchers are usually smaller, coloured differently, and possess different features from the lower pitchers. These upper pitchers usually form as the plant reaches maturity and the plant grows taller. To keep the plant steady, the upper pitchers often form a loop in the tendril, allowing it to wrap around nearby support. In some species (e.g.N. rafflesiana), different prey may be attracted by the two types of pitchers. This varied morphology also often makes identification of species difficult.[5]
Prey usually consists ofinsects, but the largest species (e.g.N. rajah andN. rafflesiana) may occasionally catch smallvertebrates, such as "frogs, birds, and small mammals".[9][10] Records of cultivated plants trapping small birds have been made.[11][12]Flowers occur inracemes or more rarely inpanicles withmale andfemale flowers on separate plants. Three species have symbiotic relationships withtreeshrews, which eat the nectar produced by the plant and defecate into the pitchers, providing valuable nutrients.[13]
Nepenthes areinsect-pollinated, the primary agents being flies (includingblow flies,midges, andmosquitoes), moths, wasps, and butterflies.[14] Their smells can range from sweet to musty orfungus-like.[15]Seed is typically produced in a four-sided capsule which may contain 50–500 wind-distributed seeds, consisting of a centralembryo and two wings, one on either side (thoughN. pervillei differs).
The genus iscytologicallydiploid, with all studied species having achromosome number of2n=80.[16][17] This high number is thought to reflectpaleopolyploidy (likely 8x or 16x).[17][18][19][20]
About170 species ofNepenthes are currently recognised as valid. This number is increasing, with several new species being described each year.[21]
The genus nameNepenthes was first published in 1737 inCarl Linnaeus'sHortus Cliffortianus.[22] It references a passage inHomer'sOdyssey, in which thepotion "Nepenthes pharmakon" is given toHelen by anEgyptian queen. "Nepenthes" (Ancient Greek:νηπενθές) literally means "without grief" (νηnē = "not",πένθοςpenthos = "grief") and, inGreek mythology, is a drug that quells all sorrows with forgetfulness.[15][page needed][23] Linnaeus explained:
If this is not Helen'sNepenthes, it certainly will be for all botanists. What botanist would not be filled with admiration if, after a long journey, he should find this wonderful plant. In his astonishment, past ills would be forgotten when beholding this admirable work of the Creator! [translated from Latin byHarry Veitch][24]
The plant Linnaeus described wasN. distillatoria, called bāndurā (බාඳුරා), a species from Sri Lanka.[15][page needed]
Nepenthes was formally published as ageneric name in 1753 in Linnaeus's famousSpecies Plantarum, which establishedbotanical nomenclature as it exists today.Nepenthes distillatoria is thetype species of the genus.[25]
The name "monkey cups" was discussed in the May 1964 issue ofNational Geographic, in whichPaul A. Zahl wrote:[26]
The carriers called them "monkey cups", a name I had heard elsewhere in reference toNepenthes, but the implication that monkeys drink the pitcher fluid seemed farfetched. I later proved it true. In Sarawak, I found anorangutan that had been raised as a pet and later freed. As I approached it gingerly in the forest, I offered it a half-full pitcher. To my surprise, the ape accepted it, and with the finesse of a lady at tea, executed a delicate bottoms-up.
The plants are often calledkantong semar (Semar's pocket) in Indonesia andsako ni Hudas (Judas'money bag) in the Philippines.[citation needed]
An absence of evidence of intermediate species, fossil or living (i.e. amissing link), does not allow forming aphylogenetic timeline for the development of the distinctive traits of modernNepenthes, which include its relatively rare strictdioecy and carnivorous pitchers. AlthoughNepenthes is distantly related to several modern genera, among these, even the carnivorous relatives [the sundews (Drosera), Venus flytrap (Dionaea muscipula), waterwheel plant (Aldrovanda), and dewy pine (Drosophyllum)], all lack those traits. Among knownNepenthes, no protomodern characteristics or large variations are found, which suggests that all extant species radiated from a single close ancestor bearing all the modern traits.Phylogenetic comparisons of thechloroplastmatKgene sequences betweenNepenthes species and with related species support this conclusion, long genetic distance betweenNepenthes and others, and abruptly diverging "pom-pon" grouping of theNepenthes species .[27]
Fossilized pollen ofNepenthes-like plants living on the northernTethys Sea from 65 to 35 million years ago indicates that then-warmer Europe may have been where the proto-Nepenthes developed, and then escaped to Asia and India as Africa collided with Europe and the ensuingclimate change wiped out the ancestral species in the original habitat. About 20 million years ago,Borneo,Sumatra, andSulawesi and possibly even the Philippines were connected to mainland Asia, providing a bridge for the colonization of most sites ofNepenthes species radiation. The extensive land bridges in the area 20,000 years ago during the ice age would have provided access to the remaining sites ofNepenthes populations inOceania. The main complication with this hypothesis is the presence ofNepenthes on the distant islands ofSeychelles andMadagascar. The seeds were thought to have been transferred byseabirds andshorebirds, which rest during their migrations in swampy habitats and may have inadvertently picked up the seeds. This hypothesis is possibly reinforced by the success of the lowland swamp-dwellingN. distillatoria in colonizing so many locations.[27][dubious –discuss]
The genusNepenthes is mostly found within theMalay Archipelago, with thegreatest biodiversity found on Borneo, Sumatra, and the Philippines,[28][29] especially in theBorneo montane rain forests. The full range of the genus includes Madagascar (N. madagascariensis andN. masoalensis), the Seychelles (N. pervillei), Sri Lanka (N. distillatoria), and India (N. khasiana) in the west to Australia (N. mirabilis,N. rowanae,N. parvula, andN. tenax) and New Caledonia (N. vieillardii) in the southeast. Most species are restricted to very small ranges, including some found only on individual mountains. These limited distributions and the inaccessibility of the regions often means some species go decades without being rediscovered in the wild (e.g.N. deaniana, which was rediscovered 100 years after its initial discovery). About 10 species have population distributions larger than a single island or group of smaller islands.Nepenthes mirabilis has the distinction of being the most widely distributed species in the genus, ranging fromIndochina and throughout the Malay Archipelago to Australia.[5][30][31]
Because of the nature of the habitats thatNepenthes species occupy, they are often graded as either lowland or highland species, depending on theiraltitude abovesea level, with 1,200 m (3,937 ft) the rough delineation between lowland and highland. Species growing at lower altitudes require continuously warm climates with little difference between day and night temperatures, whereas highland species thrive when they receive warm days and much cooler nights.Nepenthes lamii grows at a higher altitude than any other in the genus, up to 3,520 m (11,549 ft).[5][31]
MostNepenthes species grow in environments that provide highhumidity and precipitation and moderate to high light levels. A few species, includingN. ampullaria, prefer the dense, shaded forests, but most other species thrive on the margins of tree/shrub communities or clearings. Some species (e.g.N. mirabilis) have been found growing inclear-cut forest areas, roadsides, and disturbed fields. Other species have adapted to growing insavanna-like grass communities. The soils in whichNepenthes species grow are usually acidic and low in nutrients, being composed ofpeat, white sand,sandstone, or volcanic soils. Exceptions to these generalities include species that thrive in soils with highheavy metal content (e.g.N. rajah), on sandy beaches in thesea spray zone (e.g.N. albomarginata). Other species grow oninselbergs and aslithophytes, while others, such asN. inermis, can grow asepiphytes with no soil contact.[5]
The most obvious interaction betweenNepenthes species and their environments, including other organisms, is that ofpredator and prey.Nepenthes species attract their prey through active production of attractive colours, sugarynectar, and sweet scents. From this relationship, the plants primarily gainnitrogen andphosphorus to supplement their nutrient requirements for growth, given these soil nutrients are typically lacking. The most frequent prey is an abundant and diverse group ofarthropods, withants and otherinsects topping the menu. Other arthropods found frequently includespiders,scorpions, andcentipedes, whilesnails andfrogs are more unusual, but not unheard of. The most uncommon prey forNepenthes species includes rats found inN. rajah. The composition of prey captured depends on many factors, including location, but can incorporate hundreds of individual insects and many different species.[5] While manyNepenthes species are generalists in what they capture, at least one,N. albomarginata, has specialised and almost exclusively trapstermites and produces nearly no nectar.Nepenthes albomarginata gains its name from the ring of whitetrichomes directly beneath the peristome. These trichomes—or "hairs"—are palatable to termites and will attract them to the pitcher. In the course of collecting the edible trichomes, hundreds or thousands of termites will fall into the pitcher.[32][33]
N. bicalcarata provides space in the hollow tendrils of its upper pitchers for the carpenter antCamponotus schmitzi to build nests. The ants take larger prey from the pitchers, which may benefitN. bicalcarata by reducing the amount ofputrefaction of collected organic matter that could harm the natural community ofinfaunal species that aid the plant's digestion.[35]
N. lowii has also formed a dependent relationship, but with vertebrates instead of insects. The pitchers ofN. lowii provide a sugary exudate reward on the reflexed pitcher lid (operculum) and a perch fortree shrew species, which have been found eating the exudate and defecating into the pitcher. A 2009 study, which coined the term "tree shrew lavatories", determined between 57 and 100% of the plant's foliar nitrogen uptake comes from thefaeces of tree shrews.[36] Another study showed the shape and size of the pitcher orifice ofN. lowii exactly match the dimensions of a typical tree shrew (Tupaia montana).[37][38] A similar adaptation was found inN. macrophylla,N. rajah,N. ampullaria, and is also likely to be present inN. ephippiata.[38][39]
Similarly,N. hemsleyana, which is native toBorneo, has a symbiotic partnership withHardwicke's woolly bat.[40] During the day, a bat may roost above the digestive fluid inside the pitcher. While a bat is inside, it may defaecate, with the plant gaining nitrogen from the droppings. Further research has discovered that the shape and design of the pitcher has evolved to be an acoustic reflector to make it easier for bats to echo-locate, and distinguishes it from other closely related species that don't make good roosts.[41][42]
Organisms that spend at least part of their lives within the pitchers ofNepenthes species are often calledNepenthes infauna. The most common infaunal species, often representing the toptrophic level of the infaunal ecosystem, are many species ofmosquito larvae. Other infaunal species includefly andmidge larvae, spiders,mites, ants, and even a species of crab (Geosesarma malayanum). Many of these species specialise to one pitcher plant species and are found nowhere else. These specialists are callednepenthebionts. Others, often associated with but not dependent onNepenthes species, are called nepenthophiles. Nepenthexenes, on the other hand, are rarely found in the pitchers, but will often appear when putrefaction approaches a certain threshold, attracting fly larvae that would normally not be found in the pitcher infaunal community. The complex ecological relationship between pitcher plants and infauna is not yet fully understood, but the relationship may bemutualistic: the infauna is given shelter, food, or protection, and the plant that harbours the infauna receives expedited breakdown of captured prey, increasing the rate of digestion and keeping harmful bacterial populations repressed.[35][43][44]
Nepenthes digestive fluids are sterile before pitchers open and contain secondary metabolites and proteins that act asbactericides and fungicides after the pitcher opens. While the digestive fluid is being produced, the pitcher is not yet open, so there is no chance of microbial contamination. During pitcher development, at least 29 digestive proteins includingproteases,chitinases,pathogenesis-related proteins andthaumatin-like proteins are produced in the pitcher fluid. In addition to breaking down prey, these can act as antimicrobial agents.[45] When the pitchers open, the fluid is exposed to bacteria, fungal spores, insects and rain. Often pitchers have a lid that covers the trap, excepting a few (e.g.N. lowii,N. attenboroughii andN. jamban), preventing rain water from entering. The lid inhibits rainwater from diluting the digestive fluid. Once the bacteria and fungi enter the fluid, secondary metabolites are produced in addition to antimicrobial proteins.[46]Naphthoquinones, a class of secondary metabolite, are commonly produced, and these either kill or inhibit the growth and reproduction of bacteria and fungi.[47] This adaptation could have evolved sinceNepenthes plants that could produce secondary metabolites and antimicrobial proteins to kill bacteria and fungi were most likely more fit. Plants that produced antimicrobial compounds could prevent loss of valuable nutrients gained from insects within the pitcher. SinceNepenthes cannot digest certain bacteria and fungi, the bactericides and fungicides allow plants to maximize nutrient uptake.[citation needed]
The earliest known record ofNepenthes dates back to the 17th century. In 1658, French colonial governorÉtienne de Flacourt published a description of a pitcher plant in his seminal workHistoire de la Grande Isle de Madagascar. It reads:[48]
It is a plant growing about 3 feet high which carries at the end of its leaves, which are 7 inches long, a hollow flower or fruit resembling a small vase, with its own lid, a wonderful sight. There are red ones and yellow ones, the yellow being the biggest. The inhabitants of this country are reluctant to pick the flowers, saying that if somebody does pick them in passing, it will not fail to rain that day. As to that, I and all the other Frenchmen did pick them, but it did not rain. After rain these flowers are full of water, each one containing a good half-glass. [translated from French inPitcher-Plants of Borneo][15]
Flacourt called the plantAmramatico, after a local name. More than a century later, this species wasformally described asN. madagascariensis.[49]
The second species to be described wasN. distillatoria, theSri Lankanendemic. In 1677, Danish physicianThomas Bartholin made brief mention of it under the nameMiranda herba, Latin for "marvellous herb".[50] Three years later, Dutch merchantJacob Breyne referred to this species asBandura zingalensium, after a local name for the plant.[51]Bandura subsequently became the most commonly used name for the tropical pitcher plants, until Linnaeus coinedNepenthes in 1737.[15]
Nepenthes distillatoria was again described in 1683, this time by Swedish physician and naturalistHerman Niklas Grim.[52] Grim called itPlanta mirabilis destillatoria or the "miraculous distilling plant", and was the first to clearly illustrate a tropical pitcher plant.[15] Three years later, in 1686, English naturalistJohn Ray quoted Grim as saying:[53]
The root draws up moisture from the earth which with the help of the sun's rays rises up into the plant itself and then flows down through the stems and nerves of the leaves into the natural utensil to be stored there until used for human needs. [translated from Latin inPitcher-Plants of Borneo][15]
One of the earliest illustrations ofNepenthes appears in Leonard Plukenet'sAlmagestum Botanicum of 1696.[54] The plant, calledUtricaria vegetabilis zeylanensium, is undoubtedlyN. distillatoria.[15]
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Around the same time, German botanistGeorg Eberhard Rumphius discovered two newNepenthes species in theMalay Archipelago. Rumphius illustrated the first one, now considered synonymous withN. mirabilis, and gave it the nameCantharifera, meaning "tankard-bearer". The second, referred to asCantharifera alba, is thought to have beenN. maxima. Rumphius described the plants in his most famous work, the six-volumeHerbarium Amboinense, a catalogue of theflora ofAmbon Island. However, it would not be published until many years after his death.[55]
After going blind in 1670, when the manuscript was only partially complete, Rumphius continued work onHerbarium Amboinensis with the help of clerks and artists. In 1687, with the project nearing completion, at least half of the illustrations were lost in a fire. Persevering, Rumphius and his helpers first completed the book in 1690. However, two years later, the ship carrying the manuscript to the Netherlands was attacked and sunk by the French, forcing them to start over from a copy that had fortunately been retained by Governor-GeneralJohannes Camphuijs. TheHerbarium Amboinensis finally arrived in the Netherlands in 1696. Even then, the first volume did not appear until 1741, 39 years after Rumphius's death. By this time, Linnaeus's nameNepenthes had become established.[15]
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Nepenthes distillatoria was again illustrated inJohannes Burmann'sThesaurus Zeylanicus of 1737. The drawing depicts the end of a flowering stem with pitchers. Burmann refers to the plant asBandura zeylanica.[56]
The next mention of tropical pitcher plants was made in 1790, when Portuguese priestJoão de Loureiro describedPhyllamphora mirabilis, or the "marvellous urn-shaped leaf", fromVietnam. Despite living in the country for around 35 years, it seems unlikely that Loureiro observed living plants of this species, as he stated the lid is a moving part,actively opening and closing. In his most celebrated work,Flora Cochinchinensis, he writes:[57]
[...] (the) leaf-tip ends in a long hanging tendril, twisted spirally in the middle, from which hangs a sort of vase, oblong, pot-bellied, with a smooth lip with a projecting margin and a lid affixed to one side, which of its own nature freely opens and closes in order to receive the dew and store it. A marvellous work of the Lord! [translated from French inPitcher-Plants of Borneo][15]
Phyllamphora mirabilis was eventually transferred to the genusNepenthes by Rafarin in 1869.[58] As such,P. mirabilis is thebasionym of this most cosmopolitan of tropical pitcher plant species.[35]
Loureiro's description of a moving lid was repeated byJean Louis Marie Poiret in 1797. Poiret described two of the fourNepenthes species known at the time:N. madagascariensis andN. distillatoria. He gave the former its current name and called the latterNepente de l'Inde, or simply "Nepenthes of India", although this species is absent from the mainland. InJean-Baptiste Lamarck'sEncyclopédie Méthodique Botanique, he included the following account:[49]
This urn is hollow, as I have just said, usually full of soft, clear water, and then closed. It opens during the day and more than half the liquid disappears, but this loss is repaired during the night, and the next day the urn is full again and closed by its lid. This is its sustenance, and enough for more than one day because it is always about half-full at the approach of night. [translated from French inPitcher-Plants of Borneo][15]
With the discovery of new species andSir Joseph Banks' original introduction of specimens to Europe in 1789, interest inNepenthes grew throughout the 19th century, culminating in what has been called the "Golden Age ofNepenthes" in the 1880s.[5][15] However, the popularity of the plants dwindled in the early 20th century, before all but disappearing byWorld War II. This is evidenced by the fact that no new species were described between 1940 and 1966. The revival of global interest in the cultivation and study ofNepenthes is credited toJapanese botanistShigeo Kurata, whose work in the 1960s and 1970s did much to bring attention to these plants.[21]
Nepenthes may be cultivated in greenhouses. Easier species includeN. alata,N. ventricosa,N. khasiana, andN. sanguinea. These four species are highlanders (N. alata has both lowland and highland forms), some easy lowlander species areN. rafflesiana,N. bicalcarata,N. mirabilis, andN. hirsuta.[59]
Highland forms are those species that grow in habitats generally higher in elevation, and thus exposed to cooler evening temperatures. Lowland forms are those species growing nearer to sea level. Both forms respond best to rainwater (but some tap water works as long as it is flushed monthly with rainwater or water low in dissolved solid and chemicals), bright light (though some species can grow in full sun), a well-drained medium, good air circulation and relatively high humidity, although easier species such asN. alata can adapt to lower humidity environments. Highland species must have night-time cooling to thrive in the long term. Chemical fertilisers are best used at low strength. Occasional feeding with frozen (thawed before use)crickets may be beneficial. Terrarium culture of smaller plants, such asN. bellii,N. × trichocarpa andN. ampullaria, is possible, but most plants will get too large over time.[60][61]
Plants can be propagated by seed, cuttings, andtissue culture. Seeds are usually sown on damp choppedSphagnummoss, or on sterile plant tissue culture media once they have been properly disinfected. The seeds generally become nonviable soon after harvesting, so seed are not usually the preferred method of propagation. A 1:1 mixture of orchid medium with moss orperlite has been used for germination and culture. Seed may take two months to germinate, and two years or more to yield mature plants. Cuttings may be rooted in dampSphagnum moss in a plastic bag or tank with high humidity and moderate light. They can begin to root in one to two months and start to form pitchers in about six months.Tissue culture is now used commercially and helps reduce collection of wild plants, as well as making many rare species available to hobbyists at reasonable prices.Nepenthes species are considered threatened or endangered plants and all of them are listed inCITES Appendix II, with the exception ofN. rajah andN. khasiana which are listed in CITES Appendix I.[62] The CITES listing means all international trade (including in parts and derivatives) is controlled by the CITES permitting system, with wildsourced specimens of Appendix I species prohibited from commercial international trade.[citation needed]
There are manyhybridNepenthes and numerous namedcultivars. Some of the more well-known, artificially produced hybrids and cultivars include:[citation needed]
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