Nepenthes rajah ist eine Kannenpflanzenart aus der Familie der Kannenpflanzengewächse (Nepenthaceae). Sie ist eine fleischfressende Pflanze und kommt nur in einem kleinen Gebiet der Insel Borneo vor. Ihre Kannen sind mit die größten aller Kannenpflanzen, wodurch sie nicht nur Insekten, sondern auch größere Tiere fangen und verdauen kann.
Nepenthes rajah ist ein Halbstrauch, der, einer Winde vergleichbar, am Boden entlangwächst, aber zu klettern beginnt, sobald er mit einem Objekt in Kontakt kommt, an dem die Pflanze sich hochranken kann. Die Sprossachse ist bis zu drei Zentimeter dick und wird in der Regel bis zu drei Meter lang, große Exemplare können jedoch auch bis zu sechs Meter Länge erreichen. Nepenthes rajah bildet – anders als andere Arten der Gattung – keine Ausläufer, ältere Pflanzen bilden jedoch Sprösslinge an der Stängelbasis.
Es handelt sich, bedingt durch ihr Habitat, um eine sehr langsam wachsende Pflanzenart. Bis zur ersten Blüte vergehen mindestens zehn Jahre und bis die Pflanze ihre volle Größe erreicht hat, rund einhundert Jahre. Alle Teile junger Pflanzen sind mit langen, weiß-braunen Haaren bewachsen, ausgewachsene Pflanzen sind jedoch unbehaart.
Die lederigen Blätter werden in gleichmäßigen Abständen von ungefähr zwanzig Zentimetern entlang der Sprossachse gebildet. An jedem Knoten sitzt ein bis zu fünfzehn Zentimeter langer, längsgerillter Blattstiel, der in eine bis zu 80 Zentimeter lange und 15 Zentimeter breite, breitlinealisch-lanzettliche scheinbare Blattspreite übergeht, die aber im strengen Sinne nur einen umgebildeten Blattgrund darstellt. Dieser wird geteilt von einer starken Mittelrippe, ab ihrem Ansatz verlaufen von der Mittelrippe aus sechs bis zehn Seitenrippen, von diesen aus wiederum laufen verzweigte Adern schräg zum Blattrand. Rund drei Zentimeter vor dem stumpf abgerundeten Ende des Blattgrundes tritt die Mittelrippe unterhalb aus dieser heraus und geht in eine bis zu fünfzig Zentimeter lange und bis zu drei Zentimeter dicke Ranke über, die am Kannenansatz endet. Erst die Kanne selbst ist dann die eigentliche Blattspreite.
Die Kannen von Nepenthes rajah (siehe obere Abb.) gelten gemeinhin als die größten aller Kannenpflanzen, obgleich auch die Kannen der weniger bekannten Arten Nepenthes merrilliana und Nepenthes truncata sowie Nepenthes northiana und Nepenthes villosa ähnlich groß werden können.
Wie viele Kannenpflanzen bildet Nepenthes rajah zwei verschiedene Kannenarten aus (Kannendimorphismus), nämlich Boden- und Luftkannen (siehe untere Abb.). Luftkannen, die sich im Gegensatz zu den am Boden liegenden Kannen frei hängend in den oberen Regionen der Pflanzen finden, sind bei Nepenthes rajah allerdings sehr selten.
Die urnen- bis eiförmigen Bodenkannen sind außen rostrot und innen hellgrün bis rot. Sie werden bis zu 35 Zentimeter hoch und erreichen einen Durchmesser von bis zu 18 Zentimetern. Vom Rankenansatz an aufwärts bis zum Peristom (dem Rand der Kannenöffnung) verlaufen zwei im Abstand von rund zwei Millimetern von Fransen gesäumte, bis zu 25 Millimeter breite Flügel. Die Kannenöffnung ist elliptisch, abgeflacht und um 45° von außen nach innen geneigt. Das Peristom ist bis zu vier Zentimeter breit und auf jeder Seite fünf- bis sechsmal bogig eingedreht, die sich so bildenden Zähne stehen von oben nach unten in abnehmender Distanz zueinander. Das Peristom wird aus zahlreichen feinen, querstehenden Rippen gebildet, die im Abstand von 0,5 bis 2 Millimeter voneinander stehen und sich als Zähne über das Peristom hinaus bis zu 5 Millimeter in das Innere der Kanne biegen.
Ein typisches Merkmal der Kannen ist der große, gewölbte Deckel. Er ist eiförmig bis breitlinealisch geformt, herzförmig am Ansatz und stumpf abgerundet an der Spitze. Er wird bis zu 20 Zentimeter lang und 13 Zentimeter breit und hat eine tief eingesenkte, kielartige Mittelrippe. Am Ansatz des Deckels steht ein bis zu zwei Zentimeter langer Sporn, auf seiner Unterseite finden sich mit bloßem Auge sichtbare Nektardrüsen eingelassen. Das Innere der Kannen ist vollständig mit 300 bis 800 Drüsen pro cm² bedeckt, die der zum Fang ausgerüsteten oberen Hälfte sind dabei ausgesprochen klein, die der unteren, verdauenden Hälfte bedeutend größer. Die Kannen enthalten bei einem Gesamtvolumen von bis zu vier Litern bis zu zwei Liter Flüssigkeit.
Die erheblich kleineren Luftkannen der Pflanzen sind trichterförmig, ihre Flügel zu Rippen reduziert und weniger intensiv eingefärbt, sind ansonsten aber den Bodenkannen gleich.
Bekannt ist Nepenthes rajah auch wegen ihres Beutespektrums. Obwohl sich die Beute in der Regel aus Insekten zusammensetzt, sind in ihren Kannen wiederholt auch Ratten gefunden worden. Es wird angenommen, dass diese beim Versuch, die Kannenflüssigkeit zu trinken, abrutschten und ertranken. Nepenthes rajah galt lange Zeit als einzige Karnivore, die zumindest gelegentlich Säugetiere fangen konnte, wenngleich eine zweifelsfreie dokumentarische Belegung eines Säugetierfangs fehlte. Im September 2006 sorgte die Entdeckung einer bereits halbverdauten Maus im Kelch einer Nepenthes truncata im Botanischen Garten von Lyon für eine Relativierung der These, Nepenthes rajah sei die einzige Kannenpflanze, die in der Lage sei Säugetiere zu fangen.
Nepenthes rajah kann zu jeder Zeit des Jahres blühen. Wie alle Kannenpflanzen ist auch sie zweihäusig, das heißt, eine Pflanze ist entweder weiblich oder männlich, nie aber zwittrig. Die am Ansatz zehn und an der Spitze bis zu sieben Millimeter dicken Blütenstandsstiele sind bis zu achtzig Zentimeter, die Blütentrauben bis zu vierzig Zentimeter lang. Der Blütenstand ist im Anfangsstadium dicht behaart, mit zunehmender Reife verringert sich die Behaarung vor allem im unteren Bereich, bleibt aber dicht im oberen Bereich, am Blütenstiel und dem Perigon sowie an den Fruchtknoten.
Die zahlreichen Blüten sind innen grünlich weiß, außen braun und riechen stark süßlich. Im unteren Bereich des Blütenstands stehen je zwei Blüten an einem der bis zu 25 Millimeter langen Blütenstiele, die zum oberen Bereich hin zunehmend kürzer werden und nur noch eine Einzelblüte tragen. Die bis zu acht Millimeter langen Blütenblätter sind elliptisch bis breitlinealisch und stumpf gerundet, bei der weiblichen Blüte sind die Blütenblätter schmaler als bei der männlichen. Die Staubfäden sind drei bis vier Millimeter, die Staubbeutel bis zu einem Millimeter lang. Die Pollen der Pflanze werden bis zu zehn Kilometer weit verbreitet, was die Bildung von Hybriden begünstigt (siehe unten).
Die gelbbraunen Kapselfrüchte sind ein bis zwei Zentimeter lang, verdickt und leicht behaart, die Samen sind fadenförmig, drei bis acht Millimeter lang und werden vom Wind verbreitet (Anemochorie).
Die Kannen aller Kannenpflanzenarten sind nicht nur Fallen, die zum Fang und der Verdauung von Tieren dienen. Sie bieten auch vielen, teils spezialisierten, Tier- und Insektenarten Unterschlupf oder gar einen Lebensraum. Da Gestalt und Größe der Kannen ebenso stark differieren wie die Areale der Arten, gibt es zahlreiche Organismen, die auf einzelne Arten spezialisiert sind, so auch bei Nepenthes rajah. Die Kannenflüssigkeit ist die Heimat der Larven zweier nach ihr benannter Stechmückenarten, nämlich Culex rajah und Toxorhynchites rajah, neben diesen finden sich aber auch unspezialisierte Larven der Arten Culex jenseni, Uranotaenia moultoni und einer noch unbeschriebenen Art der Gattung Tripteroides.
Von einigen Affenarten, darunter Koboldmakis, ist bekannt, dass sie die Kannen seitlich aufschlitzen und sich am Inhalt der Kannen gütlich tun.
Nepenthes rajah ist auf Borneo im Nordosten der Insel endemisch in den Regenwaldgebieten des Kinabalu und des benachbarten Tambuyukon angesiedelt.
Nepenthes rajah ist ein Spezialist, der ausschließlich auf dünnen, nährstoffarmen Böden auf ultrabasischem Gestein mit einem hohen Gehalt an Magnesium sowie Nickel und Chrom siedelt. Die beiden letzten Metalle sind für die meisten Pflanzen giftig, Nepenthes rajah ist diesen gegenüber jedoch resistent und kann so konkurrenzarm diese ökologische Nische besetzen. Die Pflanzen wachsen auf offenen, losen Grasböden, die starken Regenfällen ausgesetzt sind, die jedoch wegen der mangelnden Fähigkeit des Bodens zur Wasserspeicherung extrem schnell wieder ablaufen. Sie finden sich häufig begleitet von Seggen (Carex).
Nepenthes rajah ist eine sogenannte Hochlandart, da sie nur in Höhe von 1500 bis 2650 m NN vorkommt. In diesen Höhen können die Temperaturen nachts bis auf den Gefrierpunkt fallen, tagsüber erreichen die Temperaturen nur selten mehr als 25 °C. Die relative Luftfeuchtigkeit schwankt dabei von 65 % am Tage bis 95 % in der Nacht. Auch tagsüber können diese Faktoren stark schwanken, da hohe Temperaturen und, abhängig von diesen, niedrigere Luftfeuchtigkeit nur durch die intensive Sonneneinstrahlung entstehen. Durch (häufig auftretende) Bewölkung fällt dann die Temperatur und die Luftfeuchtigkeit steigt rapide; ein Effekt, der durch die offene Vegetation und die zunehmende Höhe begünstigt wird. Zusätzlich sind die Habitate heftigen Winden und starken Regenfällen ausgesetzt, die durchschnittlichen jährlichen Niederschlagswerte liegen bei 3000 mm.
Nepenthes rajah ist als Art nur wenig variabel, es existieren weder Unterarten, Varietäten noch Formen, wegen seiner Unverkennbarkeit kam es auch nie zu Synonymien. Die Art stand in der Gattung bisher isoliert ohne engere Verwandte, 1998 jedoch kam es auf den Philippinen zur Entdeckung einer neuen Art, die insbesondere nach kannenmorphologischen Gesichtspunkten mit Nepenthes rajah verwandt sein könnte. Die Art wurde 2007 als Nepenthes mantalingajanensis erstbeschrieben, nachdem sie lange als Nepenthes spec. Palawan 1 geführt worden war. Da eine molekulargenetische Untersuchung der Gattung noch aussteht, konnte auch diese Methode noch keinen näheren Aufschluss über die genaue Position von Nepenthes rajah innerhalb der Gattung geben.
Nepenthes rajah hybridisiert mit einigen anderen Kannenpflanzenarten, begünstigt wird dies durch das relativ weite Verwehen der Pollen und die ganzjährige Blütezeit. Nachgewiesen sind Hybriden mit allen anderen am Kinabalu vorkommenden Kannenpflanzenarten (mit der Ausnahme von Nepenthes lowii).
Derzeit sind folgende natürlichen Hybriden bekannt:
Die beiden letzten Hybriden sind formal beschrieben worden und haben eigene Namen bekommen. Beide sind auch zur sexuellen Vermehrung fähig, sie sind daher als bereits „stabilisierte Hybriden“ bezeichnet worden, die möglicherweise Vorstufen zu neuen Arten darstellen. Dieser Rang wurde für sie bereits auch diskutiert, hat sich aber nicht durchgesetzt.
Nepenthes rajah ist von der IUCN auf ihrer Roten Liste als bedrohte Art (EN – B1+2e) eingestuft worden und seit 1981 auf Anhang 1 des Washingtoner Artenschutzabkommens gelistet, der höchsten CITES-Schutzstufe überhaupt, die jedweden Handel mit Wildpflanzen untersagt. Dies war notwendig geworden, weil durch ihre Beliebtheit bei Sammlern ihre Bestände insbesondere in den 1970er Jahren stark übersammelt wurden. Durch diese Unterschutzstellung, kommerzielle Nachzuchten, das gestiegene Umweltbewusstsein bei Sammlern und aufgrund der Tatsache, dass ein Großteil der Vorkommen im Kinabalu National Park liegen, haben sich die Bestände inzwischen wieder erholt, so dass eine Abstufung auf Gefährdet (VU) gerechtfertigt erscheint.
Nepenthes rajah wurde 1851 von Hugh Low während seiner ersten Besteigung des Kinabalu entdeckt und 1859 von Joseph Dalton Hooker beschrieben. Spencer St. John fand 1862 erstmals eine Ratte und damit ein Säugetier in einer der Kannen. 1878 sammelte Frederick William Burbidge erstmals lebende Exemplare für die britische Firma Veitch and Sons, die ab 1881 interessierten (Privat-)Gärtnern angeboten und im Folgejahr erstmals auf der Jahresausstellung der Royal Horticultural Society öffentlich präsentiert wurden. Weil die Kulturbedingungen jedoch sehr anspruchsvoll waren, sich das modische Interesse an den Kannenpflanzen allgemein wieder verlor und mit dem Niedergang der Firma Veitch ab 1905 auch keine Nachzuchten mehr kamen, verschwanden die Pflanzen allmählich wieder aus menschlicher Hand, die letzte bekannte Pflanze der Zeit war die der Irish National Botanic Gardens in Glasnevin, Irland, aber auch sie überlebte nicht.
Erst in den 1970er Jahren erwachte das Interesse der Öffentlichkeit an den Kannenpflanzen wieder, insbesondere aufgrund der allgemein stärker werdenden Beliebtheit fleischfressender Pflanzen. Insbesondere das Buch Nepenthes of Mount Kinabalu von Shigeo Kurata rückte dabei den Fokus wieder auf die Arten des Kinabalu, darunter auch auf Nepenthes rajah.
In ihrer Heimat werden Abbildungen der Pflanze häufig als Postkartenmotiv und zu Werbezwecken für entsprechende Touristenziele, insbesondere den Kinabalu National Park, verwandt. 1996 veröffentlichte Malaysia eine vierteilige Briefmarkenserie mit Motiven zum Thema Kannenpflanzen, eines der Motive war Nepenthes rajah.
Der Name „rajah“ stammt aus dem malayischen und bedeutet „König“. Der Name wurde zu Ehren des Abenteurers James Brooke gewählt, dem ersten Weißen Raja von Sarawak, daher findet sich im Englischen auch gelegentlich der Name „Rajah Brooke's Pitcher Plant“.
Große Teile des Artikels entstammen dem englischsprachigen Artikel en:Nepenthes rajah in der Version vom 1. Juni 2006.
Nepenthes rajah ist eine Kannenpflanzenart aus der Familie der Kannenpflanzengewächse (Nepenthaceae). Sie ist eine fleischfressende Pflanze und kommt nur in einem kleinen Gebiet der Insel Borneo vor. Ihre Kannen sind mit die größten aller Kannenpflanzen, wodurch sie nicht nur Insekten, sondern auch größere Tiere fangen und verdauen kann.
Nepenthes rajah /nɪˈpɛnθiːz ˈrɑːdʒə/ is a carnivorous pitcher plant species of the family Nepenthaceae. It is endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Malaysian Borneo.[3] Nepenthes rajah grows exclusively on serpentine substrates, particularly in areas of seeping ground water where the soil is loose and permanently moist. The species has an altitudinal range of 1,500–2,650 metres (4,920–8,690 ft) a.s.l. and is thus considered a highland or sub-alpine plant. Due to its localised distribution, N. rajah is classified as an endangered species by the IUCN and listed on CITES Appendix I.[2]
The species was collected by Hugh Low on Mount Kinabalu in 1858, and described the next year by Joseph Dalton Hooker, who named it after James Brooke, the first White Rajah of Sarawak. Hooker called it "one of the most striking vegetable productions hither-to discovered".[4] Since being introduced into cultivation in 1881, Nepenthes rajah has always been a much sought-after species. For a long time, the plant was seldom seen in private collections due to its rarity, price, and specialised growing requirements. However, recent advances in tissue culture technology have resulted in prices falling dramatically, and N. rajah is now relatively widespread in cultivation.
Nepenthes rajah is most famous for the giant urn-shaped traps it produces, which can grow up to 41 cm high[5] and 20 cm wide.[6] These are capable of holding 3.5 litres of water[7] and in excess of 2.5 litres of digestive fluid, making them probably the largest in the genus by volume. Another morphological feature of N. rajah is the peltate leaf attachment of the lamina and tendril, which is present in only a few other species.
Nepenthes rajah traps vertebrates and even small mammals, with drowned rats having been observed in the pitcher-shaped traps.[8] It is one of only three Nepenthes species documented as having caught mammalian prey in the wild, the others being N. rafflesiana and N. attenboroughii. N. rajah is also known to occasionally trap small vertebrates such as frogs, lizards, and even birds, although these cases probably involve sick animals and certainly do not represent the norm. Insects, and particularly ants, comprise the staple prey in both aerial and terrestrial pitchers.
Although Nepenthes rajah is most famous for trapping and digesting animals, its pitchers are also host to a large number of other organisms, which are thought to form a mutually beneficial (symbiotic) association with the plant. Many of these animals are so specialised that they cannot survive anywhere else, and are referred to as nepenthebionts. N. rajah has two such mosquito taxa named after it: Culex rajah and Toxorhynchites rajah.
Another key feature of N. rajah is the relative ease with which it is able to hybridise in the wild. Hybrids between it and all other Nepenthes species on Mount Kinabalu have been recorded. However, due to the slow-growing nature of N. rajah, few hybrids involving the species have been artificially produced yet.
Joseph Dalton Hooker described Nepenthes rajah in 1859, naming it in honour of Sir James Brooke, the first White Rajah of Sarawak.[9] In the past, the Latin name was written as Nepenthes Rajah,[4][10][11][12][13] since it derives from a proper noun. However, this capitalisation is considered incorrect today. 'Rajah Brooke's Pitcher Plant'[14] is an accurate, but seldom-used common name. N. rajah is also sometimes called the 'Giant Malaysian Pitcher Plant'[15] or simply 'Giant Pitcher Plant', although the binomial name remains by far the most popular way of referring to this species. The specific epithet rajah means "King" in Malay and this, coupled with the impressive size of its pitchers, has meant that N. rajah is often referred to as the "King of Nepenthes".[16]
Latin description: Folia mediocria petiolata, lamina oblonga v. lanceolata, apice peltata, nervis longitudinalibus utrinque 4–5; ascidia rosularum ignota; ascidia inferiora et superiora maxima, urceolata, alis 2 subfimbriatis, ore maximo obliquo; peristomio in collum breve elongato, expanso, 10–30 mm lato, costis 1/2–2 distantibus, dentibus 2–4 x longioribus quam latis; operculo maximo ovato-cordato, facie inferiore prope basin carina valida exaltata; inflorescentia racemus magnus pedicellis inferioribus c. 20–25 mm longis 2-floris, superioribus brevioribus 1-floris; indumentum parcum, villosum v. villoso-tomentosum.[13]
Botanical description: Stem: generally prostrate or decumbent; not climbing, coarse, 15–30 mm thick, ≤6 m long (usually ≤3 m), yellow to green in colour, internodes ≤20 cm, cylindrical. Leaves: coriaceous, shortly petiolate, yellow to green in colour, with a wavy outer margin. Lamina oblong-lanceolate, 25–80 cm long and 10–15 cm wide, rounded and peltate at the apex, rounded at the base, abruptly attenuate towards the petiole. Tendril inserted 2–5 cm below the leaf apex. Petiole canaliculate, winged, ≤15 cm long, ≤1 cm thick, dilated at the base, with a sheath that clasps the stem for 3/4 of the circumference. Longitudinal veins 3–4 (rarely 5) on each side, originating from the basal part of the midrib, running parallel in the outer half of the lamina, pennate veins running obliquely towards the margin, irregularly reticulate in the outer part of the lamina. Tendrils about as long as the lamina, ≤50 cm long, 5–6 mm thick near the lamina, 10–25 mm thick near the pitcher, curved downwards, yellow to red in colour, darker near the pitcher. Pitchers: urceolate to short-ellipsoidal, 20–41 cm high,[5] 11–20 cm wide,[6] red to purple on the outside, inside surfaces lime green to purple in colour, with two fimbriate wings running almost from the base to the mouth, broader and more fimbriate towards the top, 6–25 mm wide under the mouth, the fringe segments ≤7 mm long, 2–4 mm apart. Glandular region covers the entire inner surface of the pitcher, about 300–800 glands/cm2, the glands in the lower part (digestive zone) not overarched, large such that the interspaces only form polygons, overarched in the upper half (conductive/retentive zone). Mouth horizontal to oblique, the front side of the pitcher 1/2 to 2/5 of the back side in length, elongated towards the lid into a neck 2.5–4 cm long. Peristome greatly expanded, 10–15 mm wide at the front side, 20–50 mm wide towards the lid, distinctly scalloped, prolongated at the interior side into a perpendicular lamina that is 10–20 mm wide, the ribs 0.5–1 mm apart at the inner side, 1–2 mm apart at the outer margin, teeth distinct, those of the interior margin 2 to 4 times as long as broad. Lid ovate to oblong, rounded at the apex, cordate at the base, 15–25 cm long, 11–20 cm wide, vaulted with a distinct keel running down the centre, midrib keeled in the basal half below, keel 5–10 mm high at some distance from the base, 3–8 mm wide, no appendages. Lower surface of the lid covered in many elevated glands, those on the keel with a wide mouth, the others with a very narrow one. Spur ≤20 mm long, unbranched, ascending from the back rib of the pitcher close to the lid, about 2 mm thick at the base, attenuate. Intermediate and upper pitchers rarely produced, conical, smaller, lighter in colour; usually yellow, wings reduced to ribs. Male inflorescence: a long raceme, peduncle 20–40 cm long, about 10 mm thick at the base, about 7 mm at the top, cylindrical, yellow-green to orange in colour, the rachis 30–80 cm long, angular and grooved, gradually attenuate. Lower partial peduncles 20–25 mm long, two-flowered, upper ones gradually shorter, one-flowered, all without bract. Flowers brownish-yellow in colour, give off strong sugary smell. Tepals elliptic to oblong, ≤8 mm long, obtuse, burgundy in colour. Staminal column 3–4 mm long, anthers in 1 of 1 1/2 whorls. Female inflorescence: generally like male inflorescence, but the tepals are somewhat narrower. Fruits short-pedicelled, 10–20 mm long, relatively thick, slightly attenuate towards both ends, orange-brown in colour, the valves 2.5–4 mm wide. Seeds filiform, 3–8 mm long, nucleus only slightly wrinkled, if at all. Indumentum: all parts of the plant covered with long, caducous, white or brown hairs when young, mature plants virtually glabrous. Stem with long spreading brown hairs when young, later glabrous. Pitchers densely covered with long spreading brown hairs when young, later sparsely hairy or glabrous. Inflorescences densely covered with adpressed brown hairs when young, later more sparsely hairy in the lower part, indumentum persistent in the upper part on the peduncles and on the perigone, ovaries densely appressedly hairy, fruits less densely hairy to glabrous. Other: colour of herbarium specimens dark-brown in varying hues.[13][17]Nepenthes rajah, like virtually all species in the genus, is a scrambling vine. The stem usually grows along the ground, but will attempt to climb whenever it comes into contact with an object that can support it. The stem is relatively thick (≤30 mm) and may reach up to 6 m in length, although it rarely exceeds 3 m.[18] N. rajah does not produce runners as some other species in the genus, but older plants are known to form basal offshoots. This is especially common in plants from tissue culture, where numerous offshoots may form at a young age.
Leaves are produced at regular intervals along the stem. They are connected to the stem by sheathed structures known as petioles. A long, narrow tendril emanates from the end of each leaf. At the tip of the tendril is a small bud which, when physiologically activated, develops into a functioning trap. Hence, the pitchers are modified leaves and not specialised flowers as is often believed. The green structure most similar to a normal leaf is specifically known as the lamina or leaf blade.
The leaves of N. rajah are very distinctive and reach a large size. They are leathery in texture with a wavy outer margin. The leaves are characteristically peltate, whereby the tendril joins the lamina on the underside, before the apex. This characteristic is more pronounced in N. rajah than in any other Nepenthes species, with the exception of N. clipeata. However, it is not unique to these two taxa, as mature plants of many Nepenthes species display slightly peltate leaves. The tendrils are inserted ≤5 cm below the leaf apex and reach a length of approximately 50 cm.[17] Three to five longitudinal veins run along each side of the lamina and pennate (branching) veins run towards the margin. The lamina is oblong to lanceolate-shaped, ≤80 cm long and ≤15 cm wide.
All Nepenthes pitchers share several basic characteristics. Traps consist of the main pitcher cup, which is covered by an operculum or lid that prevents rainwater from entering the pitcher and displacing or diluting its contents. A reflexed ring of hardened tissue, known as the peristome, surrounds the entrance to the pitcher (only the aerial pitchers of N. inermis lack a peristome). A pair of fringed wings run down the front of lower traps and these presumably serve to guide terrestrial insects into the pitchers' mouth. Accordingly, the wings are greatly reduced or completely lacking in aerial pitchers, for which flying insects constitute the majority of prey items.
Nepenthes rajah, like most species in the genus, produces two distinct types of traps. "Lower" or "terrestrial" pitchers are the most common. These are very large, richly coloured, and ovoid in shape. In lower pitchers, the tendril attachment occurs at the front of the pitcher cup relative to the peristome and wings. Exceptional specimens may be more than 40 cm in length and hold 3.5 litres of water[7] and in excess of 2.5 litres of digestive fluid, although most do not exceed 200 ml.[19]
The largest recorded pitcher of N. rajah, measuring 41 cm, was found on March 26, 2011, during a trip to Mesilau organised by The Sabah Society.[5] The trap was discovered next to a steep sidepath of the Mesilau nature trail and was measured by Alex Lamb, son of Anthea Phillipps and Anthony Lamb, who were also on the trip.[5] It was collected for preservation at Mesilau Headquarters.[5] Another trap measuring 40 cm was spotted on the same day.[5] The previous record for a N. rajah pitcher was 38 cm.[5][6]
The lower pitchers of N. rajah are probably the largest in the genus by volume, rivaled only by those of N. merrilliana, N. truncata and the giant form of N. rafflesiana. These traps rest on the ground and are often reclined, leaning against surrounding objects for support. They are usually red to purple on the outside, whilst the inside surfaces are lime green to purple. This contrasts with all other parts of the plant, which are yellow-green. The lower pitchers of N. rajah are unmistakable and for this reason it is easy to distinguish it from all other Bornean Nepenthes species.[20]
Mature plants may also produce "upper" or "aerial" pitchers, which are much smaller, funnel-shaped, and usually more colourful than the lowers. The tendril attachment in upper pitchers is normally present at the rear of the pitcher cup. True upper pitchers are seldom seen, as the stems of N. rajah rarely attain lengths greater than a few metres before dying off and being replaced by off-shoots from the main rootstock.[21]
Upper and lower pitchers differ significantly in morphology, as they are specialised for attracting and capturing different prey. Pitchers that do not fall directly into either category are simply known as "intermediate" pitchers.
The peristome of N. rajah has a highly distinctive scalloped edge and is greatly expanded, forming an attractive red lip around the trap's mouth. A series of raised protrusions, known as ribs, intersect the peristome, ending in short, sharp teeth that line its inner margin. The inner portion of the peristome accounts for around 80% of its total cross-sectional surface length in this species.[22] Two fringed wings run from the tendril attachment to the lower edge of the peristome.
The huge, vaulted lid of N. rajah, the largest in the genus, is another distinguishing characteristic of this species. It is ovate to oblong in shape and has a distinct keel running down the middle, with two prominent lateral veins.[23] The spur at the back of the lid is approximately 20 mm long and unbranched.[24]
Nepenthes rajah is noted for having very large nectar-secreting glands covering its pitchers. These are quite different from those of any other Nepenthes and are easily recognisable. The inner surface of the pitcher, in particular, is wholly glandular, with 300 to 800 glands/cm2.[13]
Nepenthes rajah seems to flower at any time of the year. Flowers are produced in large numbers on inflorescences that arise from the apex of the main stem. N. rajah produces a very large inflorescence that can be 80 cm, and sometimes even 120 cm tall.[7][24] The individual flowers of N. rajah are produced on partial peduncles (twin stalks) and so the inflorescence is called a raceme (as opposed to a panicle for multi-flowered bunches). The flowers are reported to give off a strong sugary smell and are brownish-yellow in colour. Sepals are elliptic to oblong and ≤8 mm long.[24] Like all Nepenthes species, N. rajah is dioecious, which means that individual plants produce flowers of a single sex. Fruits are orange-brown and 10 to 20 mm long (see image). A study of 300 pollen samples taken from a herbarium specimen (J.H.Adam 2443, collected at an altitude of 1930–2320 m) found the mean pollen diameter to be 34.7 μm (SE = 0.3; CV = 7.0%).[25]
The root system of N. rajah is notably extensive, although it is relatively shallow as in most Nepenthes species.
All parts of the plant are covered in long, white hairs when young, but mature plants are virtually glabrous (lacking hair). This covering of hair is known as the indumentum.
The colour of herbarium specimens is dark-brown in varying hues (see image).
Little variation has been observed within natural populations of Nepenthes rajah and, consequently, no forms or varieties have been described. Furthermore, N. rajah has no true nomenclatural synonyms,[26] unlike many other Nepenthes species, which exhibit greater variability.
Nepenthes rajah is a carnivorous plant of the pitfall trap variety. It is famous for occasionally trapping vertebrates, even small mammals. There exist at least two records of drowned rats found in N. rajah pitchers. The first observation dates from 1862 and was made by Spenser St. John, who accompanied Hugh Low on two ascents of Mount Kinabalu.[16] In 1988, Anthea Phillipps and Anthony Lamb confirmed the plausibility of this record when they managed to observe drowned rats in a large pitcher of N. rajah.[8][16] In 2011, the discovery of a drowned mountain treeshrew (Tupaia montana) in a N. rajah pitcher was reported.[27]
Nepenthes rajah is also known to occasionally trap other small vertebrates, including frogs, lizards and even birds, although these cases probably involve sick animals, or those seeking shelter or water in the pitcher, and certainly do not represent the norm.[28] Insects, and particularly ants, comprise the majority of prey in both aerial and terrestrial pitchers.[19] Other arthropods, such as centipedes, also fall prey to N. rajah.
Nepenthes rafflesiana is one of the few other Nepenthes species reliably documented as having caught mammalian prey in its natural habitat. In Brunei, frogs, geckos and skinks have been found in the pitchers of this species.[28][29] The remains of mice have also been reported.[30] On September 29, 2006, at the Jardin botanique de Lyon in France, a cultivated N. truncata was photographed containing the decomposing corpse of a mouse.[31]
Nepenthes rajah has evolved a mutualistic relationship with mountain treeshrews (Tupaia montana) in order to collect their droppings. The inside of the reflexed lid exudes a sweet nectar. The distance from the pitcher mouth to the exudate is the same as the average body length of the mountain treeshrew. These proportions also hold true for N. lowii and N. macrophylla. As it feeds, the treeshrew defecates, apparently as a method of marking its feeding territory. It is thought that in exchange for providing nectar, the faeces provide N. rajah with the majority of the nitrogen it requires.[32][33][34][35][36] In N. lowii, N. macrophylla and N. rajah, the colour of the lower lid surface corresponds to visual sensitivity maxima of the mountain treeshrew in the green and blue wavebands, making the lid underside stand out against adjacent parts of the pitcher.[37] Of the three species, N. rajah shows the tightest 'fit', particularly in the green waveband.[37]
In 2011, it was reported that N. rajah has a similar mutualistic relationship with the summit rat (Rattus baluensis).[27][38] Whereas the mountain treeshrew visits pitchers during daylight hours, the summit rat is primarily active at night; this may be an example of resource partitioning. Daily scat deposition rates were found to be similar for both mammalian species.[38]
Although Nepenthes are most famous for trapping and digesting animals, their pitchers also play host to a large number of other organisms (known as infauna). These include fly and midge larvae, spiders (most notably the crab spider Misumenops nepenthicola), mites, ants, and even a species of crab, Geosesarma malayanum. The most common and conspicuous predators found in pitchers are mosquito larvae, which consume large numbers of other larvae during their development. Many of these animals are so specialised that they cannot survive anywhere else, and are referred to as nepenthebionts.[39]
The complex relationships between these various organisms are not yet fully understood. The question of whether infaunal animals "steal" food from their hosts, or whether they are involved in a mutually beneficial (symbiotic) association has yet to be investigated experimentally and is the source of considerable debate. Clarke suggests that mutualism is a "likely situation", whereby "the infauna receives domicile, protection and food from the plant, while in return, the infauna helps to break down the prey, increase the rate of digestion and keep bacterial numbers low".[40]
As the size and shape of Nepenthes pitchers vary greatly between species, but little within a given taxon, it is not surprising that many infaunal organisms are specially adapted to life in only the traps of particular species. N. rajah is no exception, and in fact has two mosquito taxa named after it. Culex (Culiciomyia) rajah and Toxorhynchites (Toxorhynchites) rajah were described by Masuhisa Tsukamoto in 1989, based on larvae collected in pitchers of N. rajah on Mount Kinabalu three years earlier.[41] The two species were found to live in association with larvae of Culex (Lophoceraomyia) jenseni, Uranotaenia (Pseudoficalbia) moultoni and an undescribed taxon, Tripteroides (Rachionotomyia) sp. No. 2. Concerning C. rajah, Tsukamoto noted that the "body surface of most larvae are covered in Vorticella-like protozoa".[42] At present, nothing is known of this species with regards to its adult biology, habitat, or medical importance as a vector of diseases. The same is true for T. rajah; nothing is known of its biology except that adults are not haematophagous.
Another species, Culex shebbearei, has also been recorded as an infaunal organism of N. rajah in the past. The original 1931 record by F. W. Edwards[43] is based on a collection by H. M. Pendlebury in 1929 from a plant growing on Mount Kinabalu. However, Tsukamoto notes that in light of new information on these species, "it seems more likely to conclude that the species [C. rajah] is a new species which has been misidentitied as C. shebbearei for a long time, rather than to think that both C. shebbearei and C. rajah n. sp. are living in pitchers of Nepenthes rajah on Mt. Kinabalu".[42]
Not all interactions between Nepenthes and fauna are beneficial to the plant. Nepenthes rajah is sometimes attacked by insects which feed on its leaves and damage substantial portions of the lamina. Also, monkeys and tarsiers are known to occasionally rip pitchers open to feed on their contents.[44]
Due to its size, unusual morphology and striking colouration, N. rajah has always been a very popular and highly sought-after insectivorous plant. However, despite its popularity amongst pitcher plant enthusiasts, N. rajah remains a little-known species outside the field of carnivorous plants. Due to its specialised growing requirements, it is not a suitable candidate for a houseplant and, as such, is only cultivated by a relatively small number of hobbyists and professional growers worldwide. This being the case, N. rajah is nonetheless probably the most famous of all pitcher plants. Its reputation for producing some of the most magnificent pitchers in the genus dates back to the late 19th century.[45]
Nepenthes rajah was first collected by Hugh Low on Mount Kinabalu in 1858.[14] It was described the following year by Joseph Dalton Hooker, who named it after James Brooke, the first White Rajah of Sarawak. The description was published in The Transactions of the Linnean Society of London:[4]
Nepenthes Rajah, H. f. (Frutex, 4-pedalis, Low). Foliis maximis 2-pedalibus, oblongo-lanceolatis petiolo costaque crassissimis, ascidiis giganteis (cum operculo l-2-pedalibus) ampullaceis ore contracto, stipite folio peltatim affixo, annulo maximo lato everso crebre lamellato, operculo amplissimo ovato-cordato, ascidium totum æquante.—(Tab. LXXII.)
Hab.—Borneo, north coast, on Kina Balu, alt. 5,000 feet (Low). This wonderful plant is certainly one of the most striking vegetable productions hitherto discovered, and, in this respect, is worthy of taking place side by side with the Rafflesia Arnoldii. It hence bears the title of my friend Rajah Brooke, of whose services, in its native place, it may be commemorative among botanists. . . . I have only two specimens of leaves and pitchers, both quite similar, but one twice as large as the other. Of these, the leaf of the larger is 18 inches long, exclusive of the petioles, which is as thick as the thumb and 7–8 broad, very coriaceous and glabrous, with indistinct nerves. The stipes of the pitcher is given off below the apex of the leaf, is 20 inches long, and as thick as the finger. The broad ampullaceous pitcher is 6 inches in diameter, and 12 long: it has two fimbriated wings in front, is covered with long rusty hairs above, is wholly studded with glands within, and the broad annulus is everted, and 1–11⁄2 inch in diameter. Operculum shortly stipitate, 10 inches long and 8 broad.
The inflorescence is hardly in proportion. Male raceme, 30 inches long, of which 20 are occupied by the flowers; upper part and flowers clothed with short rusty pubescence. Peduncles slender, simple or bifid. Fruiting raceme stout. Peduncles 11⁄2 inches long, often bifid. Capsule, 3⁄4 inch long, 1⁄3 broad, rather turgid, densely covered with rusty tomentum.
Spenser St. John wrote the following account of his encounter with N. rajah on Mount Kinabalu in Life in the Forests of the Far East published in 1862:[46]
Another steep climb of 800 feet brought us to the Marei Parei spur, to the spot where the ground was covered with the magnificent pitcher-plants, of which we had come in search. This one has been called the Nepenthes Rajah, and is a plant about four feet in length, with broad leaves stretching on every side, having the great pitchers resting on the ground in a circle about it. Their shape and size are remarkable. I will give the measurement of one, to indicate the form: the length along the back nearly fourteen inches; from the base to the top of the column in front, five inches; and its lid a foot long by fourteen inches broad, and of an oval shape. Its mouth was surrounded by a plaited pile, which near the column was two inches broad, lessening in its narrowest part to three-quarters of an inch. The plaited pile of the mouth was also undulating in broad waves. Near the stem the pitcher is four inches deep, so that the mouth is situated upon it in a triangular manner. The colour of an old chalice is a deep purple, but that of the others is generally mauve outside, very dark indeed in the lower part, though lighter towards the rim; the inside is of the same colour, but has a kind of glazed and shiny appearance. The lid is mauve in the centre, shading to green at the edges. The stems of the female flowers we found always a foot shorter than those of the male, and the former were far less numerous than the latter. It is indeed one of the most astonishing productions of nature. [...] The pitchers, as I have before observed, rest on the ground in a circle, and the young plants have cups of the same form as those of the old ones. While the men were cooking their rice, we sat before the tent enjoying our chocolate and observing one of our followers carrying water in a splendid specimen of the Nepenthes Rajah, desired him to bring it to us, and found that it held exactly four pint bottles. It was 19 inches in circumference. We afterwards saw others apparently much larger, and Mr. Low, while wandering in search of flowers, came upon one in which was a drowned rat.
Nepenthes rajah was first collected for the Veitch Nurseries by Frederick William Burbidge in 1878, during his second trip to Borneo.[47] Shortly after being introduced into cultivation in 1881, N. rajah proved very popular among wealthy Victorian horticulturalists and became a much sought-after species. A note in The Gardeners' Chronicle of 1881 mentions the Veitch plant as follows: "N. rajah at present is only a young Rajah, what it will become was lately illustrated in our columns...".[48] A year later, young N. rajah plants were displayed at the Royal Horticultural Society's annual show for the first time.[49] The specimen exhibited at the show by the Veitch Nurseries, the first of this species to be cultivated in Europe, won a first class certificate.[50] In Veitch's catalogue for 1889, N. rajah was priced at £2.2s per plant.[51] During this time, interest in Nepenthes had reached its peak. The Garden reported that Nepenthes were being propagated by the thousands to keep up with European demand.
However, dwindling interest in Nepenthes at the turn of the century saw the demise of the Veitch Nurseries and consequently the loss of several species and hybrids in cultivation, including N. northiana and N. rajah. By 1905, the final N. rajah specimens from the Veitch nurseries were gone, as the cultural requirements of the plants proved too difficult to reproduce.[49] The last surviving N. rajah in cultivation at this time was located at the National Botanic Gardens at Glasnevin in Ireland, however this soon perished also.[49] It would be many years before N. rajah was reintroduced into cultivation.
Early publications: Transact. Linn. Soc., XXII, p. 421 t. LXXII (1859); MIQ., Ill., p. 8 (1870); HOOK. F., in D.C., Prodr., XVII, p. 95 (1873); MAST., Gard. Chron., 1881, 2, p. 492 (1881); BURB., Gard. Chron., 1882, 1, p. 56 (1882); REG., Gartenfl., XXXII, p. 213, ic. p. 214 (1883); BECC., Mal., III, p. 3 & 8 (1886); WUNSCHM., in ENGL. & PRANTL, Nat. Pflanzenfam., III, 2, p. 260 (1891); STAPF, Transact. Linn. Soc., ser. 2, bot., IV, p. 217 (1894); BECK, Wien. Ill. Gartenz., 1895, p. 142, ic. 1 (1895); MOTT., Dict., III, p. 451 (1896); VEITCH, Journ. Roy. Hort. Soc., XXI, p. 234 (1897); BOERL., Handl., III, 1, p. 54 (1900); HEMSL., Bot. Mag., t. 8017 (1905); Gard. Chron., 1905, 2, p. 241 (1905); MACF., in ENGL., Pflanzenr., IV, 111, p. 46 (1908); in BAIL., Cycl., IV, p. 2129, ic. 2462, 3 (1919); MERR., Bibl. Enum. Born., p. 284 (1921); DANS., Trop. Nat., XVI, p. 202, ic. 7 (1927).[13]
Early illustrations: Transact. Linn. Soc., XXII, t. LXXII (1859) optima; Gard. Chron., 1881, 2, p. 493 (1881) bona, asc. 1; Gartenfl., 1883, p. 214 (1883) bona, asc. 1; Wien. Ill. Gartenfl., 1895, p. 143, ic. 1 (1895) asc. 1; Journ. Roy. Hort. Soc., XXI, p. 228 (1897) optima; Bot. Mag., t. 8017 (1905) optima; BAIL., Cycl., IV, ic. 2462, 3 (1919) asc. 1; Trop. Nat., XVI, p. 203 (1927) asc. 1.[13]
Early collections: North Borneo. Mt. Kinabalu, IX 1913, Herbarium of the Sarawak Museum (material without flowers or fruits); Marai-parai Spur, 1-4 XII 1915, Clemens 11073, Herbarium Bogoriense, the Herbarium of the Buitenzorg Botanic Gardens (male and female material); 1650 m, 1892, Haviland 1812/1852, Herbarium of the Sarawak Museum (male and female material).[13]
In recent years there has been renewed interest in Nepenthes worldwide. Much of the plants' current popularity can probably be attributed to Shigeo Kurata, whose book Nepenthes of Mount Kinabalu (1976), which featured the best colour photography of Nepenthes to date, did much to bring attention to these unusual plants.
Not surprisingly, N. rajah is a relatively well known plant in Malaysia, especially its native Sabah. The species is often used to promote Sabah, and specifically Kinabalu National Park, as a tourist destination, and features prominently on postcards from the region. Nepenthes rajah has appeared on the covers of several popular Nepenthes publications, including Nepenthes of Mount Kinabalu (Kurata, 1976) and Nepenthes of Borneo (Clarke, 1997), both published in Kota Kinabalu, Malaysia. On April 6, 1996, Malaysia issued a series of four postage stamps depicting some of its more famous Nepenthes species. Two 30¢ stamps, featuring N. macfarlanei and N. sanguinea, as well as two 50¢ stamps, depicting N. lowii and N. rajah, were released.[52] The N. rajah stamp has been assigned a unique identification number in two popular stamp numbering systems: Scott #580 and Yvert #600. Curiously, the peltate leaf attachment that is so characteristic of this species is not shown. Nepenthes rajah was featured in the first episode of Kingdom of Plants 3D, a natural history documentary series presented by David Attenborough.[53]
Nepenthes rajah is not generally considered to be closely related to any other species, due to its unusual pitcher and leaf morphology. However, several attempts have been made to deduce natural groupings within the genus Nepenthes, which have grouped N. rajah with other species thought to share certain traits with it.
The Nepenthes were first split up in 1873, when Hooker published his monograph on the genus, titled "Nepenthaceae". Hooker distinguished N. pervillei from all other taxa based on its seeds, which lack the appendages typical of most Nepenthes. He placed it in the monotypic subgenus Anourosperma. All other species were subsumed in the second subgenus, Eunepenthes.
A second attempt to establish a natural subdivision within the genus was made in 1895 by Günther Beck von Mannagetta und Lerchenau in "Die Gattung Nepenthes".[54] Beck kept the two subgenera created by Hooker, but divided Eunepenthes into three subgroups: Retiferae, Apruinosae and Pruinosae. Nepenthes rajah formed part of the Apruinosae (Latin: pl. of apruinosa: not frosted).
Nepenthes taxonomy was once again revised in 1908 by John Muirhead Macfarlane in his own monograph, "Nepenthaceae".[55] Oddly, Macfarlane did not name the groups he distinguished. His revision is not generally considered to be a natural division of the genus.
In 1928, B. H. Danser published his seminal monograph, "The Nepenthaceae of the Netherlands Indies", in which he divided Nepenthes into six clades, based on observations of herbarium material.[56] The clades were: the Vulgatae, Montanae, Nobiles, Regiae, Insignes and Urceolatae. Danser placed N. rajah in the Regiae (Latin: pl. of rēgia: royal). The Regiae clade as proposed by Danser is shown in the adjacent table.
Most of the species in this clade are large plants with petiolate leaves, an indumentum of coarse reddish-brown hairs, raceme-like inflorescence, and funnel-shaped (infundibulate) upper pitchers. All bear a characteristic appendage on the lower surface of the lid near the apex. With the exception of N. lowii, the Regiae all have a mostly flattened or expanded peristome. The majority of species comprising Regiae are endemic to Borneo. Based on current understanding of the genus, Regiae appears to reflect the relationships of its members quite well, although the same cannot be said for the other clades.[57] Despite this, Danser's classification was undoubtedly a great improvement on previous attempts.
The taxonomical work of Danser (1928) was revised by Hermann Harms in 1936. Harms divided Nepenthes into three subgenera: Anurosperma Hooker.f. (1873), Eunepenthes Hooker.f. (1873) and Mesonepenthes Harms (1936) (Latin: meso: middle; "middle" Nepenthes). The Nepenthes species found in the subgenera Anurosperma and Mesonepenthes differ from those in the Vulgatae, where Danser had placed them. Harms included N. rajah in the subgenus Eunepenthes together with the great majority of other Nepenthes; Anurosperma was a monotypic subgenus, while Mesonepenthes contained only three species. He also created an additional clade, the Distillatoriae (after N. distillatoria).
In his 1976 book, Nepenthes of Mount Kinabalu, Shigeo Kurata presented detailed photographs of lid nectar glands and the digestive glands of the trap interior. He divided the latter into the "lower", "upper" and "middle" parts.
More recently, biochemical analysis has been used as a means to determine cladistical relationships between Nepenthes species. In 1975, David E. Fairbrothers et al.[58] first suggested a link between chemical properties and certain morphological groupings, based on the theory that morphologically similar plants produce chemical constituents with similar therapeutic effects.
In 2002, phytochemical screening and analytical chromatography were used to study the presence of phenolic compounds and leucoanthocyanins in several naturally occurring hybrids and their putative parental species (including N. rajah) from Sabah and Sarawak. The research was based on leaf material from nine dry herbarium specimens. Eight spots containing phenolic acids, flavonols, flavones, leucoanthocyanins and 'unknown flavonoid' 1 and 3 were identified from chromatographic profiles. The distributions of these in the hybrid N. × alisaputrana and its putative parental species N. rajah and N. burbidgeae are shown in the adjacent table. A specimen of N. × alisaputrana grown from tissue culture (in vitro) was also tested.
Phenolic and ellagic acids were undetected in N. rajah, while concentrations of kaempferol were found to be very weak. Chromatographic patterns of the N. × alisaputrana samples studied showed complementation of its putative parental species.
Myricetin was found to be absent from all studied taxa. This agrees with the findings of previous authors (R. M. Som in 1988; M. Jay and P. Lebreton in 1972)[59][60] and suggests that the absence of a widely distributed compound like myricetin among the Nepenthes examined might provide "additional diagnostic information for these six species".
Several proteins and nucleotides of N. rajah have been either partially or completely sequenced. These are as follows:
In 1998, a striking new species of Nepenthes was discovered in the Philippines by Andreas Wistuba. Temporarily dubbed N. sp. Palawan 1, it bears a close resemblance to N. rajah in terms of pitcher and leaf morphology.[1][2][3] In 2007, the species was described by Wistuba and Joachim Nerz as N. mantalingajanensis.[63]
Nepenthes rajah has a very localised distribution, being restricted to Mount Kinabalu and neighbouring Mount Tambuyukon, both located in Kinabalu National Park, Sabah, Malaysian Borneo.[3] Mount Kinabalu is a massive granitic dome structure that is geologically young and formed from the intrusion and uplift of a granitic batholith. At 4095.2 m, it is by far the tallest mountain on the island of Borneo and one of the highest peaks in Southeast Asia.[64] The lower slopes of the mountain are mainly composed of sandstone and shale, transformed from marine sand and mud about 35 million years ago. Intrusive ultramafic (serpentine) rock was uplifted with the core of the batholith and forms a collar around the mountain. It is on these ultramafic soils that the flora of Mount Kinabalu exhibits the greatest levels of endemicity and many of the area's rarest species can be found here.
Nepenthes rajah seems to grow exclusively on serpentine soils containing high concentrations of nickel and chromium, which are toxic to many plant species.[15] Its tolerance of these, therefore, means that it can grow in an ecological niche where it faces less competition for space and nutrients.[65] The root systems of N. × alisaputrana[66] and N. villosa[67] are also known to be resistant to the heavy metals present in serpentine substrates. These soils are also rich in magnesium and are slightly alkaline as a result. They often form a relatively thin layer over a base of ultramafic rock and are thus known as ultramafic soils. Ultramafic soils are thought to cover approximately 16% of Kinabalu National Park. These soils have high levels of endemicity in many taxonomic groups, not least the Nepenthes. Four species in the genus, including N. rajah, can only be found within the boundaries of the park.
Nepenthes rajah usually grows in open, grassy clearings on old land slips and flat ridge tops, particularly in areas of seeping ground water, where the soil is loose and permanently moist. Although these sites can receive very high rainfall, excess water drains away quickly, preventing the soil from becoming waterlogged. N. rajah can often be found growing in grassy undergrowth, especially among sedges.
Nepenthes rajah has an altitudinal distribution of 1500–2650 m a.s.l.[9][26] and is thus considered an (ultra) highland or Upper Montane plant.[68] In the upper limit of its range, night-time temperatures may approach freezing and day-time maxima rarely exceed 25 °C.[69] Due to the night-time temperature drop, relative air humidity increases significantly, rising from 65 to 75% to over 95%. Vegetation at this height is very stunted and slow-growing due to the extreme environmental conditions that prevail. Plants are often subjected to fierce winds and driving rain, as well as exposure to intense direct sunlight. The relatively open vegetation of the upper montane forest also experiences greater fluctuations in temperature and humidity compared with lower altitudes. These changes are largely governed by the extent of cloud cover. In the absence of clouds, temperatures rise rapidly, humidity drops, and light levels may be very high. When cloud cover returns, temperatures and light levels fall, while humidity levels increase.[70] Average annual precipitation in this region is around 3000 mm.
Nepenthes rajah is classified as Endangered (EN – B1+2e) on the IUCN Red List of Threatened Species.[1] It is also listed on Schedule I, Part II of the Wildlife Conservation Enactment (WCE) 1997[71] and CITES Appendix I,[2] which prohibits commercial international trade in plants collected from the wild. However, due to its popularity among collectors, many plants have been removed from the wild illegally,[72] even though the species' distribution lies entirely within the bounds of Kinabalu Park. This led to some populations being severely depleted by over-collection in the 1970s and eventually resulted in the species' inclusion in CITES Appendix I in 1981.[73] Together with N. khasiana, it is one of only two species in the genus to feature on this list; all other Nepenthes species are covered by Appendix II.
This being the case, however, the short-term future of N. rajah seems to be relatively secure and it would perhaps be more accurately classified as Vulnerable (VU) or, taking into account protected populations in National Parks, Lower Risk conservation dependent (LR (cd)).[74] This agrees with the conservation status of N. rajah according to the World Conservation Monitoring Centre (WCMC), under which it is also considered Vulnerable. Furthermore, the species was originally treated as Vulnerable (V) by the IUCN prior to the introduction of the 1994 threat categories.
Although N. rajah has a restricted distribution and is often quoted as a plant in peril,[75] it is not rare in the areas where it does grow and most populations are now off-limits to visitors and lie in remote parts of Kinabalu National Park. Furthermore, N. rajah has a distinctive leaf shape making it difficult to illegally ship abroad even if the pitchers are removed, as an informed customs official should be able to identify it.
The recent advent of artificial tissue culture, or more specifically in vitro, technology in Europe and the United States has meant that plants can be produced in large numbers and sold at relatively low prices (~US$20–$30 in the case of N. rajah). In vitro propagation refers to production of whole plants from cell cultures derived from explants (generally seeds). This technology has, to a large extent, removed the incentive for collectors to travel to Sabah to collect the plant illegally, and demand for wild-collected plants has fallen considerably in recent years.[76]
Rob Cantley, a prominent conservationist and artificial propagator of Nepenthes plants, assesses the current status of plants in the wild as follows:[77]
This species grows in at least 2 distinct sub-populations, both of which are well protected by Sabah National Parks Authority. One of the populations grows in an area public access to which is strictly prohibited without permit. However, there has been a decline in population of mature individuals in the better known and less patrolled site. This is largely due to damage to habitat and plants by careless visitors rather than organised collection of plants. Nepenthes rajah has become common in cultivation in recent years as a result of the availability of inexpensive clones from tissue culture. I believe that these days commercial collection of this species from the wild is negligible.
This being the case, however, it appears that the genetic variability of cultivated N. rajah plants is very small, as all commercially available tissue-cultured plants are thought to belong to just four clones originating from the Royal Botanic Gardens, Kew in London, England.
However, illegal collection is not the only threat facing plants in the wild. The El Niño climatic phenomenon of 1997/98 had a catastrophic effect on the Nepenthes species on Mount Kinabalu.[78] The dry period that followed severely depleted some natural populations. Forest fires broke out in 9 locations in Kinabalu Park, covering a total area of 25 square kilometres and generating large amounts of smog. During the El Niño period, many plants were temporarily transferred to the park nursery to save at least some individuals. These were later replanted in the "Nepenthes Garden" in Mesilau (see below). In spite of this, N. rajah was one of the less affected species and relatively few plants perished as a result. Since then, Ansow Gunsalam has established a nursery close to the Mesilau Lodge at the base of Kinabalu Park to protect the endangered species of that area, including N. rajah.
The newly opened Mesilau Nature Resort, which lies near the golf course behind the village of Kundasang, is now the only place where regular visitors can hope to see this species in its natural habitat.[79] Here, several dozen N. rajah plants grow near the top of a steep landslide. Both young and mature plants are present, some with sizable pitchers that may occasionally exceed 40 cm in height[5] (see image). Daily guided tours are organised to the "Nepenthes Garden" where these plants are located. The "Nepenthes rajah Nature Trail" is subject to a fee and operates daily from 9:00 am to 4:00 pm. Almost all other natural populations of this species occur in remote parts of Kinabalu National Park, which are off-limits to tourists.[79] Visitors to the park can also see N. rajah on display in the nursery adjoining the "Mountain Garden" at Kinabalu Park Headquarters.[80]
Other known localities of wild N. rajah populations include the Marai Parai plateau, Mesilau East River near Mesilau Cave, the Upper Kolopis River, and the eastern slope of Mount Tambuyukon.[81] On Pig Hill, N. rajah grows at 1950–2320 m[82] and is sympatric with N. burbidgeae, N. tentaculata, and the natural hybrid N. × alisaputrana.[83]
Nepenthes rajah is known to hybridise with several other species with which it is sympatric. It seems to flower at any time of year and for this reason it hybridises relatively easily. Charles Clarke also notes that "N. rajah, more than any other species, appears to have been successful in having its pollen transported over considerable distances. Consequently, a number of putative N. rajah hybrids exist without the parent plant growing nearby". However, it appears that the limit as to how far pollen can be transported is approximately 10 km.[84] Hybrids between N. rajah and all other Nepenthes species on Mount Kinabalu have been recorded.[3][85] Due to the slow-growing nature of N. rajah, few hybrids involving it have been artificially produced yet.[86]
At present, the following natural hybrids are known:[26]
The "Mountain Garden" of Kinabalu National Park contains a number of well-grown Nepenthes, including the rare hybrid N. rajah × N. stenophylla. This plant has leaves resembling those of N. stenophylla, but the lid and wings are typical of N. rajah. The peristome is strongly influenced by N. stenophylla and bristles are present at the border of the lid, a unique characteristic of this hybrid.[88] It occurs at an altitude of 1500–2600 m.
A single example of N. lowii × N. rajah grows along the Mesilau nature trail.[85][87]
Two hybrids of N. rajah have been formally described and given specific names: N. × alisaputrana and N. × kinabaluensis. Both are listed on CITES Appendix II and the latter is also considered Endangered (EN (D)) under current IUCN criteria.[89]
Nepenthes × alisaputrana (originally published as "Nepenthes × alisaputraiana")[90] is named in honour of Datuk Lamri Ali, Director of Sabah Parks. It is only known from a few remote localities within Kinabalu National Park where is grows in stunted, open vegetation over serpentine soils at around 2000 m above sea level, often amongst populations of N. burbidgeae. This plant is notable for combining the best characters of both parent species, not least the size of its pitchers, which rival those of N. rajah in volume (≤35 cm high, ≤20 cm wide).[91] The other hybrids involving N. rajah do not exhibit such impressive proportions. The pitchers of N. × alisaputrana can be distinguished from those of N. burbidgeae by a broader peristome, larger lid and simply by their sheer size. The hybrid differs from its other parent, N. rajah, by its lid structure, indumentum of short, brown hairs, narrower and more cylindrical peristome, and pitcher colour, which is usually yellow-green with red or brown flecking. For this reason, Phillipps and Lamb (1996) gave it the common name Leopard pitcher-plant, though this is rarely used. The peristome is green to dark red and striped with purple bands. Leaves are often slightly peltate. The plant climbs well and aerial pitchers are frequently produced. N. × alisaputrana more closely resembles N. rajah than N. burbidgeae, but it is difficult to confuse this plant with either. However, this mistake has previously been made on at least one occasion; a pitcher illustrated in Insect Eating Plants & How To Grow Them (Slack, 1986) as being N. rajah was in fact N. burbidgeae × N. rajah.[92][93]
Nepenthes × kinabaluensis is another impressive plant. The pitchers get large also, but do not compare to those of N. rajah or N. × alisaputrana. It is a well-known natural hybrid of what many consider to be the two most spectacular Nepenthes species of Borneo: N. rajah and N. villosa. Nepenthes × kinabaluensis is only found on Mount Kinabalu (hence the name) and nearby Mount Tambuyukon, where the two parent species are occur sympatrically.[94] More specifically, plants are known from a footpath near Paka Cave and several places along an unestablished route on a southeast ridge, which lies on the west side of the Upper Kolopis River.[95] The only accessible location from which this hybrid is known is the Kinabalu summit trail, between Layang-Layang and the helipad, where it grows at about 2900 m in a clearing dominated by Dacrydium gibbsiae and Leptospermum recurvum trees. Nepenthes × kinabaluensis has an altitudinal distribution of 2420 to 3030 m.[96] It grows in open areas in cloud forest. This hybrid can be distinguished from N. rajah by the presence of raised ribs that line the inner edge of the peristome and end with elongated teeth. These are more prominent than those found in N. rajah and are clue as to the hybrid's parentage (N. villosa has highly developed peristome ribs). The peristome is coarse and expanded at the margin (but not scalloped like that of N. rajah), the lid orbiculate or reniformed and almost flat. In general, pitchers are larger than those of N. villosa and the tendril joins the apex about 1–2 cm below the leaf tip, a feature which is characteristic of N. rajah.[97] In older plants, the tendril can be almost woody. Nepenthes × kinabaluensis has an indumentum of villous hairs covering the pitchers and leaf margins, which is approximately intermediate between the parents. Lower pitchers have two fringed wings, whereas the upper pitchers usually lack these. The colour of the pitcher varies from yellow to scarlet. Nepenthes × kinabaluensis seems to produce upper pitchers more readily than either of its parents. In all respects N. × kinabaluensis is intermediate between the two parent species and it is easy to distinguish from all other Nepenthes of Borneo. However, it has been confused once before, when the hybrid was labelled as N. rajah in Letts Guide to Carnivorous Plants of the World (Cheers, 1992).[98]
Nepenthes × kinabaluensis was first collected near Kambarangoh by Lilian Gibbs in 1910 and later mentioned by Macfarlane as "Nepenthes sp." in 1914.[99] Although Macfarlane did not formally name the plant, he noted that "[a]ll available morphological details suggest that this is a hybrid between N. villosa and N. rajah".[100] The name N. × kinabaluensis was first published in Shigeo Kurata's 1976 book, Nepenthes of Mount Kinabalu, but was a nomen nudum at the time as it lacked an adequate description and information on the type specimen. The name was subsequently published validly by Kurata in 1984.[101]
Nepenthes × alisaputrana and N. × kinabaluensis are often fertile and thus may breed among themselves. Clive A. Stace writes that we may speak of "stabilised hybrids when they have developed a distributional, morphological or genetic set of characters which is no longer strictly related to that of its parents, ... if the hybrid has become an independent, recognisable, self-producing unit, it is de facto a separate species".[102] Nepenthes hurrelliana and N. murudensis are two examples of species that have a putative hybrid origin. Nepenthes × alisaputrana and N. × kinabaluensis are sufficiently stabilised that a species status has been discussed.[16] Indeed, N. kinabaluensis was described as a species by Adam & Wilcock in 1996.
Due to their dioecious nature, a hybrid involving a pair of Nepenthes species can represent one of two possible crosses, depending on which species was the female and which was the male. When the cross is known, the female (or pod) parent is usually referred to first, followed by the male (or pollen) parent. This is an important distinction, as the hybrid will usually display different morphological features according to the type of cross; the pod parent is thought to be dominant in most cases and hybrid offspring usually resemble it more than the pollen parent. Most wild plants of N. × kinabaluensis, for example, show a greater affinity to N. rajah than N. villosa and are thus thought to represent the cross N. rajah × N. villosa. However, specimens have been found that seem to be more similar to N. villosa, suggesting that they might be the reverse cross (see [4]). The same is true for other hybrids involving N. rajah.
Nepenthes rajah has always been considered to be one of the more difficult Nepenthes species to cultivate. However, in recent years, it has become apparent that the plant may not be deserving of its reputation.
Nepenthes rajah is a montane species or "highlander", growing at altitudes ranging from 1500 to 2650 m. As such, it requires warm days, with temperatures ranging (ideally) from approximately 25 to 30 °C,[103] and cool nights, with temperatures of about 10 to 15 °C.[103] The temperatures themselves are not vital (when kept within reasonable limits), but rather the temperature drop itself; N. rajah needs considerably cooler nights, with a drop of 10 °C or more being preferable. Failure to observe this requirement will almost certainly doom the plant in the long term or, at best, limit it to being a small, unimpressive specimen.
In addition, like all Nepenthes, this plant needs a fairly humid environment to grow well. Values in the region of 75% R.H.[103] are generally considered optimal, with increased humidity at night (~90% R.H.). However, N. rajah does tolerate fluctuations in humidity, especially when young, provided that the air does not become too dry (below 50% R.H.). Humidity can be easily controlled using an ultrasonic humidifier in conjunction with a humidistat.
In its natural habitat, N. rajah grows in open areas, where it is exposed to direct sunlight – it therefore needs to be provided with a significant amount of light in cultivation as well. To meet this need, many growers have used metal halide lamps in the 500–1000 watt range, with considerable success. The plant should be situated a fair distance from the light source, 1 to 2 m is recommended.[103] Depending on location, growers can utilise natural sunlight as a source of illumination. However, this is only recommended for those living in equatorial regions, where light intensity is sufficient to satisfy the needs of the plant. A photoperiod of 12 hours is comparable to that experienced in nature, since Borneo lies on the equator.[103]
Pure long-fibre Sphagnum moss is an excellent potting medium, though combinations involving any of the following – peat, perlite, vermiculite, sand, lava rock, pumice, Osmunda fibre, orchid bark and horticultural charcoal – may be used with equal success. The potting medium should be well-drained and not too compacted. Moss is useful for moisture retention near the roots. The mix should be thoroughly soaked in water prior to potting the plant.
It has been noted that N. rajah produces a very extensive root system (for a Nepenthes) and, for this reason, it is recommended that a wide pot be used to allow for proper development of the root system.[103] This also eliminates the need for frequent re-potting, which can lead to transplant shock and the eventual death of the plant.[103]
Purified water should be used for watering purposes, although 'hard water' is tolerated. This is done to minimise the build-up of minerals and chemicals in the soil. Water purity greater than 100 p.p.m. of total dissolved solids is often quoted as ideal.[104] A reverse osmosis unit can be used to filter the water or, alternatively, bottled distilled water can be purchased. Watering should be done regularly. However, plants should not be allowed to sit in water, as this may lead to root rot.
Nepenthes rajah is a carnivorous plant and, as such, supplements nutrients gained from the soil with captured prey (especially insects) to alleviate deficiencies in important elements such as nitrogen, phosphorus and potassium. Just as in nature, a cultivated plant's 'diet' may include insects and other prey items, although this is not necessary for successful cultivation. Crickets are recommended for their size and low cost. These can be purchased online or at specialist pet stores. They can simply be dropped into the pitchers by hand or placed inside using metal tongs or similar, whether dead or alive.
From trials carried out by a commercial Nepenthes nursery,[105] it appears that micronutrient solutions have "a beneficial effect on plants of improved leaf colouration, with no deleterious effects" as far as can be seen. However, more research is required to verify these results. Actual fertilisers (containing NPK) were, on the other hand, found to "cause damage to plants, promote pathogens and have no observable benefits". Hence, the use of chemical fertilisers is usually not advised.
Nepenthes rajah is a slow growing Nepenthes. Under optimal conditions, N. rajah can reach flowering size within 10 years of seed germination.
Nepenthes rajah has been a well known and highly sought after species for over a century and, as a result, there are many stories woven around this plant. One such example is the famous legend that N. rajah grows exclusively in the spray zones of waterfalls, on ultramafic soils. Although the latter is true, N. rajah is certainly not found solely in the spray zones of waterfalls and this statement seems to have little basis in fact.[3] It is likely this misconception was popularised by Shigeo Kurata's 1976 book Nepenthes of Mount Kinabalu, in which he states that "N. rajah is rather fond of wet places like swamps or the surroundings of a waterfall".[9]
This being the case, certain N. rajah plants do in fact grow in the vicinity of waterfalls (as noted by H. Steiner, 2002) "providing quite a humid microclimate",[16] which may indeed be the source of this particular misconception.
Another myth surrounding this species is that it occasionally catches small monkeys and other large animals in its pitchers. Such tales have persisted for a very long time, but can probably be explained as rodents being mistaken for other species.[106] It is interesting to note that one common name for Nepenthes plants is 'Monkey Cups'. The name refers to the fact that monkeys have been observed drinking rainwater from these plants.
Nepenthes rajah /nɪˈpɛnθiːz ˈrɑːdʒə/ is a carnivorous pitcher plant species of the family Nepenthaceae. It is endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Malaysian Borneo. Nepenthes rajah grows exclusively on serpentine substrates, particularly in areas of seeping ground water where the soil is loose and permanently moist. The species has an altitudinal range of 1,500–2,650 metres (4,920–8,690 ft) a.s.l. and is thus considered a highland or sub-alpine plant. Due to its localised distribution, N. rajah is classified as an endangered species by the IUCN and listed on CITES Appendix I.
The species was collected by Hugh Low on Mount Kinabalu in 1858, and described the next year by Joseph Dalton Hooker, who named it after James Brooke, the first White Rajah of Sarawak. Hooker called it "one of the most striking vegetable productions hither-to discovered". Since being introduced into cultivation in 1881, Nepenthes rajah has always been a much sought-after species. For a long time, the plant was seldom seen in private collections due to its rarity, price, and specialised growing requirements. However, recent advances in tissue culture technology have resulted in prices falling dramatically, and N. rajah is now relatively widespread in cultivation.
Nepenthes rajah is most famous for the giant urn-shaped traps it produces, which can grow up to 41 cm high and 20 cm wide. These are capable of holding 3.5 litres of water and in excess of 2.5 litres of digestive fluid, making them probably the largest in the genus by volume. Another morphological feature of N. rajah is the peltate leaf attachment of the lamina and tendril, which is present in only a few other species.
Nepenthes rajah traps vertebrates and even small mammals, with drowned rats having been observed in the pitcher-shaped traps. It is one of only three Nepenthes species documented as having caught mammalian prey in the wild, the others being N. rafflesiana and N. attenboroughii. N. rajah is also known to occasionally trap small vertebrates such as frogs, lizards, and even birds, although these cases probably involve sick animals and certainly do not represent the norm. Insects, and particularly ants, comprise the staple prey in both aerial and terrestrial pitchers.
Although Nepenthes rajah is most famous for trapping and digesting animals, its pitchers are also host to a large number of other organisms, which are thought to form a mutually beneficial (symbiotic) association with the plant. Many of these animals are so specialised that they cannot survive anywhere else, and are referred to as nepenthebionts. N. rajah has two such mosquito taxa named after it: Culex rajah and Toxorhynchites rajah.
Another key feature of N. rajah is the relative ease with which it is able to hybridise in the wild. Hybrids between it and all other Nepenthes species on Mount Kinabalu have been recorded. However, due to the slow-growing nature of N. rajah, few hybrids involving the species have been artificially produced yet.
Nepenthes rajah aŭ raĝa kruĉo estas orientalisa insektodigesta planto, kiu havas modifiĝintajn foliojn por kapti insektojn. La folio havas glatan, refaldiĝantan randon, kiu malebligas eskapon de la insektoj. La planto produktas digestajn enzimojn, kiuj disigas restaĵojn de la insektoj kaj la planto uzas tiujn materialojn.
La raĝa kruĉo kreskas sur insulo Borneo, havas kaptan kruĉon de 38x15 cm kaj volumenon de kelkajn litrojn (kelkfoje).
La planto estis malkovrita kaj priskribita far la botanikisto Joseph Dalton Hooker en la 19-a jarcento.
Nepenthes rajah aŭ raĝa kruĉo estas orientalisa insektodigesta planto, kiu havas modifiĝintajn foliojn por kapti insektojn. La folio havas glatan, refaldiĝantan randon, kiu malebligas eskapon de la insektoj. La planto produktas digestajn enzimojn, kiuj disigas restaĵojn de la insektoj kaj la planto uzas tiujn materialojn.
La raĝa kruĉo kreskas sur insulo Borneo, havas kaptan kruĉon de 38x15 cm kaj volumenon de kelkajn litrojn (kelkfoje).
La planto estis malkovrita kaj priskribita far la botanikisto Joseph Dalton Hooker en la 19-a jarcento.
Nepenthes rajah est une espèce de plantes carnivores à piège passif formé d'ascidies (urnes), de la famille des Nepenthaceae. Il s'agit d'une espèce endémique qui vit dans une zone très localisée, restreinte au mont Kinabalu et à son voisin, le mont Tambuyukon, dans l'État de Sabah en Malaisie sur l'île de Bornéo[1]. Nepenthes rajah est célèbre pour ses pièges géants en forme d'urnes, ils mesurent jusqu'à 35 cm de haut[2] et 18 cm de large[3]. Ces urnes peuvent contenir 3,5 litres d'eau[4] et plus de 2,5 litres de liquide digestif, ce qui en fait probablement l'espèce aux plus grandes urnes du genre Nepenthes.
Joseph Dalton Hooker décrit N. rajah en 1859, il l'a nommé en l'honneur de Sir James Brooke, le premier des Rajahs blancs de Sarawak[5]. Le nom scientifique latin fut au départ écrit Nepenthes Rajah, avec une majuscule à Rajah puisqu'il dérive d'un nom propre. Cependant la majuscule n'est plus considérée comme correcte. Le nom anglophone commun Rajah Brooke's Pitcher Plant (Plante à urnes du Râja Brooke) est rarement employé pour cette espèce, son nom scientifique binomial est celui le plus employé pour la désigner. L'épithète spécifique rajah signifie « roi » en malais et ceci, associé aux dimensions impressionnante de ses urnes, a conduit N. rajah a souvent être considéré comme le « Roi des népenthès » (« King of Nepenthes »)[6].
Nepenthes rajah, comme pratiquement toutes les espèces du genre, croît comme une plante grimpante. La tige pousse généralement sur le sol, mais tente de grimper dès qu'elle est en contact avec un objet pouvant la soutenir. La tige est relativement épaisse (diamètre inférieur ou égal à 30 mm) et peut atteindre jusqu'à 6 m de long, bien qu'elle n'excède que rarement 3 m[7]. N. rajah ne développe pas de stolons comme certaines espèces du genre, mais les plantes âgées sont connues pour former des caïeux à la base (sorte de ramification à fonction multiplicative). C'est particulièrement courant chez les plantes bouturées, qui produisent des caïeux très tôt.
Les feuilles sont produites à intervalles réguliers le long de la tige. Elles sont rattachées à la tige par une structure particulière qui entoure la tige, le pétiole. Un long et étroit cirrhe émane à l'extrémité de chaque feuille. Au bout du cirrhe se situe un bourgeon qui, lorsqu'il est physiologiquement activé, se développe en un piège fonctionnel. Ainsi, les urnes sont des feuilles transformées et non pas des fleurs spécialisées comme on le croit souvent. La structure verte la plus proche d'une feuille ordinaire est spécifiquement connue comme le limbe.
Les feuilles de N. rajah sont très distinctes et atteignent une grande taille. Elles ont une texture coriace avec un bord extérieur ondulé. Les feuilles sont nettement peltées, l'attache du pétiole se situe sous le limbe. De trois à cinq nervures longitudinales parcourent chaque face du limbe et des nervures pennées rejoignent les bords. Le limbe est de forme oblongue à lancéolée, mesurant jusqu'à 80 cm de long pour une large maximale de 15 cm. Les cirrhes sont insérés à moins de 5 cm de l'apex de la feuille et atteignent une longueur d'environ 50 cm[8].
Les urnes de tous les Nepenthes partagent des caractéristiques communes. Les pièges sont constitués d'une urne (ou ascidie), qui est recouverte par un opercule dont la fonction supposée est d'empêcher l'eau de pluie d'entrer dans l'urne et d'emporter ou de diluer son contenu. L'ouverture de l'ascidie est généralement cerclée d'un anneau, appelé péristome, constitué de tissus rigides et orienté vers le bas. Une paire d'« ailes » avec des franges, située à l'avant de l'urne, descend jusqu'à sa base. Ces ailes serviraient à guider les insectes terrestres vers la bouche de l'ascidie. Elles sont très réduites ou complètement absentes au niveau des urnes aériennes, pour lesquelles seuls les insectes volants constituent la majorité des proies.
N. rajah produit deux types distincts d'ascidies : les ascidies « inférieures » ou terrestres sont les plus fréquentes. Elles sont très volumineuses, richement colorées et de forme ovoïde. Des spécimens exceptionnels peuvent mesurer jusqu'à 40 cm de haut et contenir jusqu'à 3,5 litres d'eau[4] et plus de 2,5 litres de liquide digestif, bien que la majorité des urnes n'excède pas 200 mL[9]. Les urnes inférieures de N. rajah sont probablement les plus volumineuses du genre Nepenthes, seules les urnes de N. merrilliana, N. truncata et les formes géantes de N. rafflesiana (variété gigantea) peuvent rivaliser.
Ces pièges reposent sur le sol et prennent souvent appui sur des éléments environnants. Les urnes sont généralement rouges ou pourpres à l'extérieur, tandis que la surface intérieure est vert citron à pourpre. Cela contraste fortement avec les autres parties de la plante qui sont vert jaunâtre. Les urnes inférieures de N. rajah sont caractéristiques et ne peuvent être confondues avec d'autres espèces de Nepenthes de Bornéo[10].
Les plantes âgées peuvent également développer des ascidies « supérieures » ou « aériennes », qui sont plus petites, en forme d'entonnoir et habituellement moins colorées que les inférieures. De vraies urnes supérieures sont rarement observées. En effet la tige de N. rajah n'atteint que rarement des longueurs supérieures à quelques mètres avant de mourir et d'être remplacée par des caïeux provenant de la racine principale[11].
Les urnes supérieures et inférieures diffèrent significativement au niveau de leur morphologie, elles sont spécialisées pour attirer et capturer des proies différentes. Les ascidies qui n'entrent pas directement dans l'une ou l'autre de ces catégories sont simplement dites « intermédiaires » ; tous les intermédiaires existent a priori.
Le péristome de N. rajah est très étendu, et possède un pourtour festonné très distinctif, formant une lèvre attirante autour de la bouche de l'ascidie. Une série de saillies ou nervures strient le péristome. Ces côtes se terminent en de courtes dents effilées qui bordent le rebord intérieur du péristome. Les deux ailes à franges rejoignant l'attache du cirrhe partent du bord inférieur du péristome.
L’important opercule en forme de voûte de N. rajah, le plus grand du genre, est une autre caractéristique distinctive de cette espèce. Il est de forme ovale à oblongue et est pourvu d'une carène (ou arête centrale), le parcourant par le milieu. L'éperon à l'arrière de l'opercule mesure environ 20 mm de long et n'est pas ramifié[3].
N. rajah possède d'importantes glandes sécrétrices de nectar couvrant ses ascidies. Ces glandes sont assez différentes de celles des autres Nepenthes et sont facilement reconnaissables. La surface interne des ascidies, en particulier, est entièrement glandulaire, avec 300 à 800 glandes par cm²[12].
N. rajah semble fleurir à n'importe quelle saison de l'année. Les fleurs sont nombreuses formant une inflorescence qui se développe à l'apex de la tige principale. Le népenthès produit une très grande inflorescence qui peut mesurer 80 cm et parfois même 120 cm de hauteur[3],[4]. Les fleurs individuelles de N. rajah possèdent un pédoncule partiel (proche d'une queue), alors l'inflorescence est appelée une « grappe » (par opposition à un « panicule », avec des grappes de plusieurs fleurs). Ces fleurs sont décrites comme brun jaune et dégagent un parfum sucré fort. Les sépales sont elliptiques à oblongues et mesurent moins de 8 mm de long[3]. Comme tous les Nepenthes, N. rajah est dioïque, ce qui signifie que chaque individu produit soit des fleurs mâles (staminées) soit des fleurs femelles (pistillées), mais jamais les deux. Les fruits sont orange brun et mesurent de 10 à 20 mm de long (voir commons:Image:Nep_rajah28.jpg).
Toutes les parties de la plante sont couvertes, dans les premiers stades de développement, de longs poils blancs qui ont tendance à disparaître quand la plante devient mature. Cette couverture de poils est connue sous le nom de indumentum.
La couleur des spécimens conservés en herbier est d'un brun foncé dans différentes nuances. (Voir commons:Image:Nep_rajah19.jpg).
De petites variations ont été observées parmi les populations naturelles de Nepenthes rajah cependant, aucune forme ou variété n'a été décrite. En outre, N. rajah ne possède pas de synonymes publiés[13], à l'inverse de beaucoup d'autres espèces de Nepenthes, qui présentent des variations majeures.
Nepenthes rajah est une plante carnivore avec des pièges passifs de type « piège à urne ». Il est connu pour piéger occasionnellement des vertébrés et même de petits mammifères. Il existe au moins deux mentions de rats trouvés noyés dans des urnes de N. rajah. La première observation date de 1862 et a été faite par Spencer St. John, qui accompagna Hugh Low lors de deux ascensions du mont Kinabalu[6]. En 1988, Anthea Phillipps et Anthony Lamb confirment la plausibilité de ces captures quand ils réussissent à observer des rats noyés dans de grandes urnes de N. rajah[6],[14]. N. rajah piège occasionnellement d'autre petits vertébrés, dont des grenouilles, des lézards ou même des oiseaux, quoique ces cas aient probablement impliqué des animaux malades, cela ne représente donc certainement pas une norme. Les insectes, et en particulier les fourmis, représentent la majorité des proies des urnes aussi bien terrestres qu'aériennes[9].
Bien que les Nepenthes soient célèbres pour leur capacité à piéger et à digérer des animaux, leurs urnes servent également d'habitat pour un grand nombre d'organismes, connus sous le nom d'endofaune (infauna en anglais). Parmi ces organismes, on trouve des larves de mouche et de moucheron, des araignées (en particulier l'araignée-crabe Misumenops nepenthicola), des acariens, des fourmis, et même une espèce de crabe : Geosesarma malayanum. Le plus commun et visible des prédateurs trouvés dans des urnes est la larve de moustique, qui consomme un grand nombre d'autres larves pendant son développement. Beaucoup de ces animaux sont tellement spécialisés qu'ils ne peuvent survivre nulle part ailleurs, et sont qualifiés de symbiote des Nepenthes (nepenthebionts en anglais)[15].
Les relations complexes entre ces organismes variés ne sont actuellement pas complètement comprises. Des recherches sont nécessaires pour trancher si l'endofaune « vole » la nourriture de son hôte, ou si elle participe à une association symbiotique (bénéfices réciproques), la question fait actuellement débat. Charles Clarke suggère que le mutualisme est « une situation probable », par laquelle l'endofaune reçoit domicile, protection et nourriture de la plante, tandis qu'en retour, l'endofaune aide à la décomposition des proies, améliore le taux de digestion et conserve un nombre de bactéries faible[16].
Nepenthes rajah n'est généralement pas considéré comme étant proche d'une autre espèce, du fait de ses ascidies particulières et de la morphologie de ses feuilles. Toutefois, plusieurs tentatives ont été faites pour déduire des groupes logiques parmi le genre des Nepenthes, et ceci dans le but de montrer les relations entre les taxons inférieurs au genre. Ces tentatives ont groupé N. rajah avec d'autres espèces, censées partager des caractéristiques.
Le genre des Nepenthes a été scindé pour la première fois en 1873, quand Hooker publie sa monographie à propos de ce genre. Hooker distingue le N. pervillei de tous les autres espèces, car les graines de cette espèce ne portent pas les appendices qu'on trouve chez tous les autres Nepenthes (quoique grandement réduits chez N. madagascariensis). Il place N. pervillei dans le sous-genre monotypique Anurosperma (du latin, anuro : avec des nervures et sperma : graines). Toutes les autres espèces sont placées dans un second sous-genre, Eunepenthes (du latin, eu : vrai, les vrais Nepenthes).
Une seconde tentative pour l'établissement d'une division logique au sein du genre fut faite en 1895 par Beck dans son Monographische Skizze (en allemand, Monographische : monographie, Skizze: croquis)[17]. Beck conserve les deux sous-genres créés par Hooker, mais divise les Eunepenthes en trois sous-groupes : les Retiferae, les Apruinosae et les Pruinosae. N. rajah appartenant alors aux Apruinosae (du latin, pluriel de apruinosa : non dépoli). La plupart des taxonomistes contemporains de Beck ne donnaient qu'une faible valeur taxonomique à son groupement, puisque celui-ci était fondé sur des traits arbitraires et non utilisables en tant que base pour une classification.
La taxonomie des Nepenthes est révisée une fois de plus en 1908 par Macfarlane dans sa propre monographie[18]. Singulièrement, Macfarlane ne nomme pas les groupes qu'il distingue. Sa proposition est souvent considérée comme non naturelle.
En 1928, B. H. Danser publia une monographie, dans laquelle il divise les Nepenthes en six clades qui sont : Vulgatae, Montanae, Nobiles, Regiae, Insignes et Urceolatae. Danser place le N. rajah dans le clade des Regiae (du latin, rēgia : royal). Le clade des Regiae, tel que proposé par Danser, est détaillé dans le tableau de droite.
La majorité des espèces de ce clade sont de grandes plantes avec des feuilles pétiolées, un indumentum de poils grossiers brun rouge, une inflorescence en racème, et des ascidies supérieures en forme d'entonnoir. Toutes sont pourvues d'un appendice caractéristique sur la surface inférieure de l'opercule près de l'apex. À l'exception de N. lowii, les Regiae possèdent toutes un péristome étendu et fascié (marqué de côtes). De plus une grande majorité des espèces appartenant à ce clade sont endémiques à Bornéo. En se fondant sur la compréhension actuelle du genre, le clade Regiae semble plutôt bien refléter les relations unissant ses membres, bien qu'il n'en soit pas de même pour les autres clades[19]. En dépit de cela, la classification de Danser est indubitablement une grande avancée au regard des tentatives antérieures.
Le travail taxonomique de Danser (1928) est révisé par Harms en 1936. Harms divise les Nepenthes en trois sous-genres : Anurosperma Hooker.f. (1873), Eunepenthes Hooker.f. (1873) et Mesonepenthes Harms (1936) (du latin, meso: milieu, Nepenthes « moyens »). Les espèces de Nepenthes situées dans les sous-genres Anurosperma et Mesonepenthes diffèrent de celles situées parmi les Vulgatae, où Danser les avait placées. Harms inclut N. rajah dans le sous-genre Eunepenthes avec la grande majorité des Nepenthes ; Anurosperma est un sous-genre monotypique, tandis que Mesonepenthes contient seulement trois espèces. Il crée également un clade supplémentaire, les Distillatoriae (d'après N. distillatoria).
En 1976, Kurata suggère que les glandes présentes dans les ascidies des Nepenthes sont particulières à chaque espèce et peuvent ainsi être utilisées pour distinguer des taxons proches ou même être utilisées comme base de la classification. Kurata étudies deux types de glandes : les glandes à nectar sur l'opercule et les glandes digestives à l'intérieur de l'ascidie. Il divise ces dernières selon trois zones : supérieure, moyenne et inférieure. Bien que cette nouvelle approche apporte un éclairage supplémentaire sur les similarités entre certaines espèces, elle a depuis été largement abandonnée par les taxonomistes et botanistes spécialisées dans ce genre, en faveur d'une nomenclature classique fondée sur une description des caractères morphologiques.
Plus récemment, des analyses biochimiques ont servi comme moyen de détermination des relations unissant différentes espèces de Nepenthes au sein d'un clade. En 1975, David E. Fairbrothers et al.[20] suggèrent les premiers l'existence d'une relation entre les propriétés chimiques et certains groupements sur une base morphologique. Ils se fondent sur la théorie selon laquelle des espèces végétales similaires sur le plan morphologique produisent des molécules chimiques aux effets thérapeutiques similaires[21].
En 2002, une étude fondée sur des criblages phytochimiques et des chromatographies analytiques a été conduite sur la présence de composés phénoliques et de leucoanthocyanines chez plusieurs hybrides naturelles et leurs espèces parentes présumées (N. rajah y compris) provenant de Sabah et Sarawak[21]. Elle a été effectuée sur des feuilles provenant de neuf spécimens séchés en herbier. Huit bandes ont été distinguées, elle contenaient des acides phénoliques, des flavonols, des flavones, des leucoanthocyanines et des « flavonoïdes inconnus » (numérotés 1 et 3). Leur répartition chez l'hybride N. × alisaputrana et ses espèces parentes présumées N. rajah et N. burbidgeae sont représentées dans le tableau suivant. Un spécimen de N. × alisaputrana issu de bouturage (in vitro) a également été testé.
Distribution de composés phénoliques et de leucoanthocyanines chez N. × alisaputrana, N. burbidgeae et N. rajah Taxon 1 2 3 4 5 6 7 8 Spécimen N. × alisaputrana + ++ 3+ 3+ + ++ 3+ + J2442 in vitro + ++ 3+ 3+ + ++ + + N. burbidgeae 3+ ++ 3+ 3+ - + - - J2484 N. rajah - - + ± ++ ++ 3+ + J2443 Légende : 1: acide phénolique, 2: acide ellagique, 3: quercétine, 4: kaempférol, 5: lutéoline, 6: 'Flavonoïde inconnu 1', 7: 'Flavonoïde inconnu 3', 8: Cyanidine± : bande très faible, + : faible bande, ++ : bande bien présente, 3+ : bande très présente,
- : absent, J = Jumaat
Source : OnLine Journal of Biological Sciences 2 (9): 623-625, 2002.[PDF]
Les acides phénoliques et ellagiques n'ont pas été détectés chez N. rajah, tandis que des concentrations très faibles de kaempférol ont été détectées. Les chromatogrammes de N. × alisaputrana ont montré la complémentarité de ses deux parents présumés[21].
La myricétine est absente chez tous les taxa étudiés. C'est en accord avec les résultats antérieurs obtenus par d'autres auteurs (Som en 1988 ; Jay et Lebreton, 1972)[22],[23]. L'absence de ce composé, largement présent au sein de la biosphère, chez les Nepenthes étudiés pourraient offrir « additional diagnostic information » (des informations supplémentaires) pour ces six espèces[21].
Plusieurs protéines et acides nucléiques du N. rajah ont été partiellement ou complètement séquencés. Les voici :
Récemment, une nouvelle espèce remarquable de Nepenthes a été découverte aux Philippines par Andreas Wistuba. Surnommé temporairement N. sp. Palawan 1, ce népenthès ressemble fortement au N. rajah au niveau de la morphologie des ascidies et des feuilles. (Voir [1][2][3]). Du fait de la distance géographique séparant les deux espèces, il est peu probable qu'elles soient étroitement apparentées de quelque façon que ce soit. Ainsi, ce cas pourrait représenter un exemple d'évolution convergente, processus par lequel deux organismes non étroitement apparentés acquièrent indépendamment des caractéristiques similaires, évoluant dans des écosystèmes différents, mais comparables. La description formelle de N. sp. Palawan 1 est en cours.
Du fait de ses dimensions, de sa morphologie particulière et de ses couleurs remarquables, N. rajah a toujours été une plante carnivore appréciée et convoitée. Toutefois, en dépit de sa popularité parmi les amateurs du genre, il faut reconnaître que Nepenthes rajah demeure peu connu en dehors du domaine des plantes carnivores. En raison des besoins spécifiques requis pour sa croissance, ce n'est pas une plante d'appartement appropriée, ainsi, seul un petit cercle de passionnés et de professionnels de par le monde la cultive. La réputation de ses ascidies, comme étant parmi les plus belles du genre, date de la fin du XVIIe siècle.
Nepenthes rajah a été découvert le 7 mars 1851 (ou juste avant) par Hugh Low, pendant sa première ascension du mont Kinabalu. Il fut décrit et formellement nommé par Hooker huit ans plus tard. L'espèce a été ramassée pour la première fois pour les pépinières Veitch par Frederick William Burbidge en 1878, pendant son second voyage à Bornéo. Peu de temps après son introduction en culture en 1881, N. rajah se révèle être très populaire parmi les riches horticulteurs victoriens et plutôt recherché. Un an plus tard, de jeunes spécimens de N. rajah sont exposés pour la première fois à l'exposition annuelle de la Royal Horticultural Society[26]. Pendant ce temps, l'intérêt pour les Nepenthes atteint des sommets. The Garden (un magazine britannique) signale que ces Nepenthes sont diffusés par milliers pour répondre à la demande européenne.
Toutefois, l'intérêt décroissant pour les Nepenthes à la fin du XIXe siècle a vu la cession des pépinières Veitch et par conséquent la perte de plusieurs espèces et hybrides cultivés, y compris N. northiana et N. rajah. En 1905, les derniers spécimens de N. rajah des pépinières Veitch meurent, les conditions de culture difficiles ne permettant pas la reproduction. Le dernier N. rajah cultivé en vie, à cette époque, est situé au Jardin botanique national de Glasnevin en Irlande, néanmoins celui-ci périt peu après[26]. Il faudra attendre un long moment avant la réintroduction en culture de N. rajah.
Un renouveau de l'intérêt pour les Nepenthes eut lieu récemment à travers le monde. La popularité actuelle de ces plantes peut en grande partie être attribuée à Shigeo Kurata, qui signa en 1976 le livre Nepenthes of Mount Kinabalu (Nepenthes du mont Kinabalu), qui présente parmi les meilleures photographies de Nepenthes à ce jour. Ce livre a sûrement attiré l'attention sur ces plantes peu habituelles.
De façon peu étonnante, N. rajah est une plante relativement connue en Malaisie, spécialement dans sa région native, le Sabah. L'espèce est souvent un sujet de promotion touristique du mont Kinabalu et figurent sur les cartes postales de la région. N. rajah apparaît sur la couverture de plusieurs publications sur les Nepenthes, dont : Nepenthes of Mount Kinabalu (Kurata, 1976) et Nepenthes of Borneo (Clarke, 1997), tous deux publiés à Kota Kinabalu. Le 6 avril 1996, la Malaisie a émis une série de quatre timbres représentant certains de leurs plus célèbres népenthès. Ce sont deux timbres de 30¢, représentant N. macfarlanei et N. sanguinea, ainsi que deux timbres de 50¢, représentant N. lowii et N. rajah[27]. Le timbre N. rajah s'est vu assigné un numéro unique au sein de deux systèmes de numérotation de timbres, le numéro 600 dans Yvert et Tellier et 580 dans le Scott catalogue. Curieusement, l'attache peltée de la feuille qui est caractéristique de cette espèce n'est pas représentée.
Nepenthes rajah vit dans une région très localisée, cette région étant réduite au mont Kinabalu et au mont Tambuyukon voisin, tous deux situés dans le parc national du Kinabalu dans l'État de Sabah en Malaisie[1] Le mont Kinabalu est un dôme granitique massif qui est géologiquement jeune et formé par intrusion d'un batholite granitique. Avec 4 095,2 m d'altitude c'est de loin le plus haut sommet de l'île de Bornéo et l'un des plus hauts d'Asie du Sud-Est[28]. Les versants inférieurs du mont sont principalement constitués de grès et de schistes, issus de la sédimentation de sable marin et de boue vieille de quelque 35 millions d'années. Une roche ultramafique intrusive (serpentine) est remontée avec le cœur de batholite formant un anneau autour du mont. C'est sur ces sols ultramafiques que la flore du mont Kinabalu montre le plus haut niveau d'endémisme et beaucoup des espèces les plus rares de la région peuvent y être trouvées.
N. rajah semble pousser uniquement sur des sols riches en serpentine, contenant de hautes concentrations de nickel et de chrome, éléments toxiques pour beaucoup d'espèces végétales. Cette tolérance signifie qu'il occupe une niche écologique où il n'a pas à faire face à une grande compétition pour l'espace ou les éléments nutritifs. Ces sols sont également riches en magnésium et sont donc faiblement alcalins. Ils forment souvent une relativement faible couche sur un socle ultramafique et sont donc appelés des sols ultramafiques. On évalue la proportion de sols ultramafiques au sein du parc national du Kinabalu à approximativement 16 %. Ces sols recèlent un haut niveau d'endémicité au sein de plusieurs groupes taxonomiques, pas seulement les Nepenthes. Quatre espèces du genre, incluant N. rajah, vivent seulement à l'intérieur des frontières du parc.
N. rajah pousse habituellement dans des espaces ouverts, des clairières herbeuses sur de vieux glissements de terrain ou sur des arêtes larges, en particulier dans des zones où de l'eau suinte, où la terre est lourde et humide en permanence. Bien que ces sites puissent recevoir d'importantes précipitations, l'eau en excès est rapidement drainée, empêchant ainsi le sol de devenir sursaturé en eau. N. rajah peut souvent être trouvé dans des sous-bois herbeux, spécialement parmi des carex.
N. rajah vit en altitude autour de 1500 à 2650 m au-dessus du niveau de la mer[13],[5], il est donc considéré comme un népenthès highland, c'est-à-dire de haute montagne[29]. Dans les plus hautes régions de son habitat, la température, la nuit, peut approcher 0°C et le jour, ne dépasse rarement les 25 °C[30]. Du fait de la chute des températures nocturnes, l'humidité relative (hygrométrie) augmente nettement, de 65-75 % à plus de 95 %. La végétation à cette altitude est particulièrement chétive et croît lentement à cause des conditions environnementales qui y prévalent. Les plantes sont souvent sujettes à des vents violents et des pluies torrentielles, mais aussi à une exposition intense aux rayons du Soleil. La végétation relativement dégagée de la forêt de haute montagne connaît donc de plus grandes fluctuations de température et d'humidité que la végétation inférieure. Ces changements sont principalement régis par l'importance de la couverture nuageuse. En l'absence de nuages, les températures augmentent rapidement, l'humidité chute, et l'ensoleillement peut être fort. Quand les nuages couvrent le ciel, on observe les phénomènes inverses[31]. Le taux moyen de précipitations est de 3 000 mm dans la région.
Nepenthes rajah est classé parmi les espèces menacées (EN – B1+2e) sur la Liste rouge de l'UICN de l'UICN[32],[33]. Il figure également sur l'Annexe I, Partie II du Wildlife Conservation Enactment (WCE) de 1997[34] et plus notoirement sur l'Annexe I du CITES[35], ce qui interdit le commerce international de plantes prélevées dans la nature. Toutefois, du fait de la grande popularité du N. rajah parmi les collectionneurs, beaucoup d'individus ont été prélevés illégalement dans la nature, bien que l'espèce ne vive qu'à l'intérieur des frontières du parc national du Kinabalu. Au cours des années 1970, cela a conduit à une sévère diminution des effectifs de certaines populations, c'est peut-être ce qui a amené à son classement au sein de l'Annexe I en 1981[36]. Avec le N. khasiana, ce sont les deux seules espèces du genre à y figurer.
Pourtant, le futur à court terme de N. rajah semble sûr et pour cette raison il pourrait être plus exactement classé comme vulnérable (VU) ou, en prenant en compte les populations protégées des parcs, comme préoccupation mineure dépendant des mesures de conservation (LR (cd))[37]. Ceci est en accord avec le centre de surveillance de la conservation de la nature qui le classe comme vulnérable. De plus, l'espèce était considérée comme vulnérable (V) par l'UICN avant l'introduction des catégories de 1994.
Quoique N. rajah pousse dans une zone restreinte et est souvent cité comme une plante en péril[38], il n'est pas rare dans sa zone de distribution et la plupart des populations sont à l'écart des visiteurs dans des parties reculées du parc national du Kinabalu. De plus, N. rajah possède des feuilles de forme remarquable ce qui rend difficile son exportation à l'étranger même si les ascidies sont retirées, puisqu'il est aisé pour un officier de douane informé de les identifier.
Les récentes avancées en matière de micropropagation, ou plus spécifiquement en techniques in vitro, en Europe et aux États-Unis, permettent de produire des plantes en grand nombre à un prix relativement bas (il est possible de trouver des pieds de N. rajah autour de 20 à 25 €). La technique de propagation in vitro permet de faire pousser une plante entière à partir d'explants (fragments d'organe ou de tissu) par exemple des graines, des méristèmes… Cette technique a, dans une large mesure, supprimé les motivations des collectionneurs à aller à Sabah pour prélever une plante illégalement, ainsi la demande de plantes collectées dans la nature a considérablement chuté[39].
Rob Cantleyn, un important avocat de la conservation et cultivateur de Nepenthes évalue le statut de conservation actuel du N. rajah :
« Cette espèce se répartit en, au moins, deux sous-populations, qui sont bien protégées par les services des parcs nationaux de Sabah. L'une des populations vit dans une zone où l'accès est strictement interdit au public sans autorisation. Néanmoins, il y a eu un déclin au sein de la population de plantes matures dans les zones les plus connues et les moins patrouillées. C'est largement le fait d'une dégradation de l'habitat et des plantes par négligence des visiteurs qu'une collecte organisée de plantes. N. rajah est récemment devenu une plante commune en culture grâce aux possibilités de clonage peu onéreuses de la micropropagation. Je pense qu'aujourd'hui la collecte commerciale de cette plante dans la nature est négligeable[40] (traduction approximative). »
Cela dit, il semble que la variabilité génétique de plants de N. rajah cultivés soit très faible, puisque toutes les plantes commercialisées semblent issues de seulement quatre souches provenant des jardins botaniques royaux de Kew à Londres.
Toutefois, les récoltes illégales ne sont pas les seules menaces pour N. rajah en milieu naturel. Le phénomène climatique El Niño de 1997/98 a eu un effet catastrophique sur les espèces de Nepenthes du mont Kinabalu. La période de sécheresse qui a suivi, a sévèrement réduit certaines populations naturelles. Neuf feux de forêt ont été recensés dans le parc de Kinabalu, couvrant une surface totale de 2 500 hectares et produisant d'épais nuages de fumée. Pendant la période El Niño, beaucoup de plantes ont été temporairement transférées dans la pépinière du parc dans le but de sauver au moins quelques individus. Ceux-ci ont été replantés dans le « jardin des Nepenthes » à Mesilau (voir ci-après). Malgré ces événements, N. rajah fut l'une des espèces les moins touchées et relativement peu de plantes périrent. Depuis, Ansow Gunsalam a fondé une pépinière fermée au pavillon de Mesilau au pied du mont Kinabalu pour protéger les espèces menacées dont N. rajah.
La Station nature de Mesilau récemment ouverte, qui se situe près du terrain de golf derrière le village de Kundasang, est maintenant le seul endroit où des visiteurs peuvent espérer observer cette espèce spectaculaire dans son habitat naturel[41]. Ici, plusieurs dizaines de plants de N. rajah poussent près du sommet d'un éboulement escarpé. Des plantes jeunes et d'autres matures sont visibles, certaines présentent des urnes approchant 35 cm de haut (voir commons:Image:Nepenthes_rajah.jpg). Du fait de leur grande taille, on pense que certains individus sont vieux de plus de 100 ans. Des visites guidées quotidienne sont organisées au « Jardin des Nepenthes » où ces plantes sont situées. Presque toutes les autres populations de Nepenthes rajah vivent dans des coins reculés du parc national du Kinabalu, qui ne sont pas visitables[41]. Les visiteurs du parc peuvent également admirer un exemplaire de N. rajah de taille moyenne situé dans la pépinière attenante au « Jardin de la montagne ».
Parmi les autres localisations connues de populations sauvages de Nepenthes rajah, il y a le plateau de Marai Parai, la rivière est de Mesilau près de la grotte de Mesilau, la rivière supérieure de Kolopis et le versant est du mont Tambuyukon[42].
Nepenthes rajah est réputé être le népenthès le plus difficile à cultiver, toutefois cette réputation semble être exagérée.
N. rajah est une espèce de montagne ou highland (haute terre), qui pousse à des altitudes comprises entre 1 500 et 2 650 m. Ainsi, elle a besoin de journées chaudes, avec des températures allant de 25 à 30 °C[43], et de nuits fraîches, avec des températures d'environ 10 à 15 °C[43]. Les températures en elles-mêmes ne sont pas vitales (toute proportion gardée), mais plutôt les écarts entre elles ; N. rajah a besoin de nuits plus froides de 10 °C ou plus. Si ces exigences ne sont pas respectées la plante déclinera, ou au mieux, restera chétive et insignifiante.
Comme tous les Nepenthes, cette plante nécessite un environnement relativement humide pour une bonne croissance. Des valeurs telles que 75 % d'humidité relative[43] sont généralement considérées comme optimales, avec une élévation de l'humidité la nuit (autour de 90 %). Toutefois, N. rajah tolère des fluctuations d'humidité, en particulier les spécimens jeunes, tant qu'elle n'est pas inférieure à 50 %. Elle peut facilement être contrôlée grâce à un humidificateur à ultrasons et un hygromètre.
Dans son habitat naturel, N. rajah pousse dans des espaces ouverts, exposé directement à la lumière du soleil ; pour cette raison il a également besoin d'une importante luminosité en culture. Beaucoup de cultivateurs utilisent des lampes halogènes de 500 à 1 000 watts. Il est souvent recommandé de les placer de 1 à 2 m des plantes[43]. Selon la localisation géographique, la lumière naturelle peut être suffisante. Toutefois ceci est seulement possible dans des régions équatoriales, où la luminosité est suffisante pour répondre au besoin de la plante. Une photopériode de douze heures se rapproche des conditions naturelles[43].
Des fibres pures de sphaigne (genre Sphagnum) font un excellent substrat de base, des combinaisons sont alors possible avec les matériaux suivants : tourbe, perlite, vermiculite, sable, roche de lave, pierre ponce, fibre d'Osmunda, substrat pour orchidée et charbon de bois d'horticulture. Le substrat doit être bien drainé et pas trop compact. La mousse permet de retenir l'humidité près des racines. Le mélange peut être entièrement détrempé dans de l'eau avant son installation.
Nepenthes rajah est une espèce de plantes carnivores à piège passif formé d'ascidies (urnes), de la famille des Nepenthaceae. Il s'agit d'une espèce endémique qui vit dans une zone très localisée, restreinte au mont Kinabalu et à son voisin, le mont Tambuyukon, dans l'État de Sabah en Malaisie sur l'île de Bornéo. Nepenthes rajah est célèbre pour ses pièges géants en forme d'urnes, ils mesurent jusqu'à 35 cm de haut et 18 cm de large. Ces urnes peuvent contenir 3,5 litres d'eau et plus de 2,5 litres de liquide digestif, ce qui en fait probablement l'espèce aux plus grandes urnes du genre Nepenthes.
Nepenthes rajah (Hook.f., 1859) è una pianta carnivora appartenente alla famiglia Nepenthaceae, diffusa nel Borneo malese.
È una pianta famosa per la produzione di ascidi di considerevoli dimensioni, dato che possono raggiungere l'altezza di 35 cm e la larghezza di 18 cm[2]. Questi ascidi sono in grado di contenere 3,5 litri di acqua[3] e più di 2,5 litri di enzimi digestivi.
La N. rajah è una delle due nepente (l'altra è la N. rafflesiana) per le quali è stata documentata la cattura come prede di piccoli mammiferi. Phillips, nel 1987 ha trovato due ratti annegati all'interno di due differenti ascidi di una Nepenthes rajah[4]. È capace di catturare anche altri piccoli vertebrati, come lucertole, rane e uccelli, sebbene si pensa che questi casi riguardino animali malati e di certo non rappresentano la norma. Generalmente, infatti, la maggior parte delle prede è costituita da insetti, soprattutto formiche.
Gli ascidi della nepente ospitano anche un grande numero di organismi animali commensali o simbionti. Molti di questi animali sono così legati agli ascidi della pianta che non sono in grado di sopravvivere lontano da essi e vengono chiamati Nepenthebionti. Due di questi sono i ditteri Culex rajah e Toxorhynchites rajah.
Nepenthes rajah, come quasi tutte le specie del suo genere, è una pianta rampicante. Lo stelo di solito cresce adiacente al terreno, ma si arrampica ogni volta che viene in contatto con un oggetto in grado di sostenerlo. Lo stelo è relativamente sottile (≤30 mm) e può raggiungere la lunghezza di circa 6 m, sebbene raramente supera i 3 m[5].
N. rajah non produce stoloni come le altre nepente, ma le piante più vecchie producono dei getti basali. Questo è comune specialmente nelle piante che derivano da coltura tissutale.
Le foglie sono prodotte ad intervalli regolari lungo lo stelo, cui sono attaccate mediante i piccioli.
Dalla parte apicale di ogni foglia si diparte un viticcio lungo e stretto, che può raggiungere la lunghezza di 50 cm[6]. Nella sua parte terminale si trova una piccola gemma che, se attivata fisiologicamente, si sviluppa in una trappola funzionante. Quindi gli ascidi sono foglie modificate e non fiori specializzati come spesso si crede.
Le foglie di N. rajah sono molto distinguibili e raggiungono grandi dimensioni. Possono essere lunghe fino ad 80 cm e larghe fino a 15 cm.
Sono peltate e di forma lanceolata, con il margine esterno ondulato. Il viticcio si diparte dalla parte inferiore della foglia, poco prima del meristema apicale. Questa caratteristica è più evidente in N. rajah che nelle altre nepente, con l'eccezione di N. clipeata.
Lungo ogni faccia della foglia corrono da tre a cinque venature longitudinali, e da queste si dipartono verso il margine fogliare delle venature pennate.
Tutti gli ascidi delle nepenthes condividono delle caratteristiche di base. Le trappole sono costituite da una coppa principale, che è coperta da un opercolo che impedisce all'acqua piovana di penetrare al suo interno e diluirne il contenuto enzimatico. Un anello di tessuto, il peristoma, circonda la bocca dell'ascidio. Un paio di "ali" frangiate attraversano la parte frontale delle trappole terrestri e servono presumibilmente per guidare gli insetti all'interno della bocca dell'ascidio. Queste ali sono assenti o molto ridotte negli ascidi aerei, che catturano principalmente insetti volanti.
N. rajah, come la maggior parte delle nepente, produce due tipi di ascidi. Gli ascidi inferiori o terrestri sono i più comuni. Sono molto grandi, riccamente colorati e di forma ovoidale. L'attaccatura del viticcio si trova nella parte frontale della coppa dell'ascidio, vicino al peristoma ed alle ali. Gli ascidi di alcuni esemplari sono in grado di raggiungere l'altezza di 40 cm e la capacità di 3,5 litri di acqua e di più di 2,5 litri di fluido digestivo, sebbene la maggior parte non superi i 200 ml[7]. Questi ascidi sono probabilmente i più grandi per volume di tutte le nepente, rivaleggiati solo da quelli di poche altre specie, quali la N. merrilliana, la N. truncata e la N. rafflesiana. Queste trappole si trovano sul terreno e sono spesso reclinate, appoggiandosi a qualsiasi oggetto in grado di sostenerle. Sono in genere di un colore che va dal rosso al porpora nella parte esterna, mentre la parte interna va dal verde al porpora. Gli ascidi inferiori di N. rajah sono inconfondibili e per questo motivo è facile distinguere questa specie da tutte le altre specie di Nepenthes del Borneo[8].
Le piante mature possono produrre, anche se raramente, degli ascidi superiori o aerei, più piccoli, imbutiformi e generalmente meno colorati di quelli terrestri. L'attaccatura del viticcio in questi ascidi si trova nella parte posteriore della coppa.
I due tipi di ascidi differiscono notevolmente nella morfologia poiché sono specializzati nella cattura di differenti tipi di prede. Gli ascidi che non ricadono in nessuna delle due categorie sono chiamati ascidi "intermedi".
Il peristoma presenta un margine dentato ben distinguibile che forma un attraente labbro attorno alla bocca dell'ascidio. Una serie di protrusioni rialzate, note come costole, intersecano il peristoma e, terminando in piccoli e corti denti, ne determinano il margine superiore. Due ali frangiate corrono dall'attaccatura del viticcio fino al margine inferiore del peristoma.
Il grande opercolo di N.rajah, il più grande del Genere, è un'altra caratteristica distintiva di questa specie. Ha una forma ovoidale o oblunga e presenta una chiglia che attraversa la sua parte mediana. Lo "sperone" posto dietro l'opercolo è lungo circa 20 mm[2].
Gli ascidi di N. rajah sono ricoperti da grandi ghiandole secernenti nettare che sono abbastanza diverse da quelle di altre Nepenthes. La superficie superiore dell'ascidio, in particolare, presenta da 300 a 800 ghiandole/cm2[9].
N. rajah fiorisce durante tutto l'anno.
I fiori sono prodotti in grande numero su dei racemi, infiorescenze con un singolo asse di ramificazione, che si sviluppano dall'apice dello stelo principale e che possono essere alti fino a 120 cm[3]. Producono un forte odore zuccherino e sono di colore bruno-giallo.
I sepali sono ellittici o oblunghi e lunghi fino a 8 mm[2].
Come tutte le specie di Nepenthes, anche N. rajah è una pianta dioica, con fiori unisessuali presenti su piante maschili e femminili.
I frutti son arancio-bruni e lunghi da 10 a 20 mm.
Il sistema radicale di N.rajah è notevolmente esteso, sebbene sia relativamente superficiale come nella maggior parte delle Nepenthaceae.
In tutte le parti delle piante giovani è presente l'indumentum, una copertura di peli lunghi e bianchi, che sono del tutto assenti nelle piante adulte.
A differenza di molte altre specie di nepente, nelle popolazioni naturali di N. rajah è stata osservata poca variabilità genetica e di conseguenza non sono state descritte né forme né varietà.
Nepenthes rajah è una pianta carnivora appartenente alla varietà che presenta la trappola ad ascidio. È famosa perché occasionalmente intrappola vertebrati o persino piccoli mammiferi. Sono stati registrati almeno due casi di ritrovamento di ratti soffocati negli ascidi di N. rajah. La prima osservazione risale al 1862 da parte di Spenser St. John, che accompagnò Hugh Low a due scalate del Monte Kinabalu.[10] Nel 1988, Anthea Phillipps e Anthony Lamb confermarono la plausibiltà di quella registrazione quando riuscirono ad osservare ratti soffocati in un largo ascidio di N. rajah.[10][11] N. rajah è conosciuta anche per la cattura occasionale di piccoli vertebrati, includendo rane, lucertole e persino uccelli, sebbene questi casi riguardino probabilmente animali malati, o che cercano un riparo oppure dell'acqua nell'ascidio, e certamente non rappresentano la norma.[12] Insetti, e particolarmente le formiche, costituiscono la maggior parte delle prede che rimangono intrappolate negli ascidi.[13] Altri artropodi, come centopiedi, cadono anch'essi preda della N. rajah.
N. rafflesiana è l'unica altra pianta della specie Nepenthes ampiamente documentata in dipendenza del fatto che cattura mammiferi nel suo ambiente naturale. Nel Brunei, rane, gechi e scinchi sono stati trovati negli ascidi di questa specie.[14] Sono stati riportati anche ritrovamenti di resti di topi.[15]
Il 29 settembre 2006, al Jardin botanique de Lyon in Francia, fu fotografata una N. truncata coltivata che conteneva il corpo in decomposizione di un topo.[16]
Lo stesso argomento in dettaglio: Simbionti delle nepenthes. Sebbene le Nepenthes siano famose per la loro capacità di intrappolare e digerire varie specie animali, le loro trappole offrono anche ospitalità ad una grande varietà di organismi (denominati infauna). Questi includono larve di mosche e moscerini, ragni (principalmente il ragno granchio Misumenops nepenthicola), acari, formiche, e anche una specie di granchio, Geosesarma malayanum. I più comuni predatori rinvenuti negli ascidi sono le larve di zanzara, che si nutrono di molte altre larve durante il loro sviluppo. Molti di questi organismi sono tanto specializzati da non poter vivere in alcun altro luogo, e sono definiti nepenthebionti.[25]
Le complesse relazioni tra questi organismi e le piante ospitanti sono ancora non del tutto comprese. Va ancora verificato sperimentalmente se l'infauna "ruba" il cibo alle Nepenthes, o se è coinvolta in un rapporto simbiontico con esse, anzi, ciò è attualmente causa di considerevoli dibattiti. Clarke avanza l'ipotesi che la simbiosi sia una "situazione accettabile", poiché "l'infauna riceve un rifugio, protezione e cibo dalla pianta, mentre in cambio l'infauna contribuisce a demolire le prede, aumentare l'efficienza della digestione e mantiene basso il numero di batteri".
Dalla N. rajah prendono nome due specie di zanzare: Culex rajah e Toxorhynchites rajah, descritte da Masuhisa Tsukamoto nel 1989, basandosi su larve raccolte in ascidi di N. rajah sul Monte Kinabalu tre anni prima. Le due specie vivevano in associazione con larve di Culex (Lophoceraomyia) jenseni, Uranotaenia (Pseudoficalbia) moultoni e un taxon non descritto, Tripteroides (Rachionotomyia) sp. No. 2. Riguardo alla C. rajah, Tsukamoto ha notato che "la superficie corporea della maggior parte di larve è ricoperta da protozoi Vorticella vivi". Attualmente, niente si sa di queste specie sulla biologia adulta, habitat, o importanza medica come vettore di malattie. Lo stesso per T. rajah; non si sa nulla della sua biologia tranne che gli adulti non sono ematofagi.
Un'altra specie, Culex shebbearei, è stata registrata come organismo appartenente all'infauna della N. rajah in passato. La segnalazione originale, nel 1931, di F. W. Edwards si basa su un prelievo di H. M. Pendlebury nel 1929 da una pianta del Monte Kinabalu. Comunque, Tsukamoto annota che alla luce di nuove informazioni su questa specie, "sembra più probabile che la specie C. rajah sia una nuova specie identificata erroneamente in C. shebbearei per un lungo periodo, che sia C. shebbearei, sia C. rajah n. sp. vivano negli ascidi delle Nepenthes rajah del Mt. Kinabalu".
È endemica del Monte Kinabalu e del vicino Monte Tambuyukon, che si trovano a Sabah, nel Borneo malese[17].
Cresce esclusivamente su substrati serpentini, in particolare in aree in cui il suolo è permanentemente umido e povero di nutrienti.
Si sviluppa ad altitudini comprese tra i 1500 ed i 2650 m s.l.m. ed è quindi considerata una pianta sub-alpina.
Nepenthes rajah (Hook.f., 1859) è una pianta carnivora appartenente alla famiglia Nepenthaceae, diffusa nel Borneo malese.
È una pianta famosa per la produzione di ascidi di considerevoli dimensioni, dato che possono raggiungere l'altezza di 35 cm e la larghezza di 18 cm. Questi ascidi sono in grado di contenere 3,5 litri di acqua e più di 2,5 litri di enzimi digestivi.
La N. rajah è una delle due nepente (l'altra è la N. rafflesiana) per le quali è stata documentata la cattura come prede di piccoli mammiferi. Phillips, nel 1987 ha trovato due ratti annegati all'interno di due differenti ascidi di una Nepenthes rajah. È capace di catturare anche altri piccoli vertebrati, come lucertole, rane e uccelli, sebbene si pensa che questi casi riguardino animali malati e di certo non rappresentano la norma. Generalmente, infatti, la maggior parte delle prede è costituita da insetti, soprattutto formiche.
Gli ascidi della nepente ospitano anche un grande numero di organismi animali commensali o simbionti. Molti di questi animali sono così legati agli ascidi della pianta che non sono in grado di sopravvivere lontano da essi e vengono chiamati Nepenthebionti. Due di questi sono i ditteri Culex rajah e Toxorhynchites rajah.
Didysis ąsotenis (Nepenthes rajah) – ąsoteninių (Nepenthaceae) šeimos vabzdžiaėdis augalas.
Ąsotėlis didelis, į jį telpa iki trijų litrų skysčio. Įprastas augalo grobis - vabzdžiai, ypač skruzdėlės, tačiau kartais įkliūna ir smulkūs stuburiniai gyvūnai (varlės, driežai, paukščiai), nors manoma, kad pastarieji būna ligoti.
Paplitęs Kalimantano saloje.
Rūšis įrašyta į Tarptautinę raudonąją knygą.
Didysis ąsotenis (Nepenthes rajah) – ąsoteninių (Nepenthaceae) šeimos vabzdžiaėdis augalas.
Ąsotėlis didelis, į jį telpa iki trijų litrų skysčio. Įprastas augalo grobis - vabzdžiai, ypač skruzdėlės, tačiau kartais įkliūna ir smulkūs stuburiniai gyvūnai (varlės, driežai, paukščiai), nors manoma, kad pastarieji būna ligoti.
Paplitęs Kalimantano saloje.
Rūšis įrašyta į Tarptautinę raudonąją knygą.
Nepenthes Rajah é uma planta carnívora da família das nepentáceas. É endêmica do Monte Kinabalu e também do Monte Tambuyukon em Sabah, Bornéu.[1] N. Rajah cresce exclusivamente sobre substratos de serpentina, particularmente em áreas de infiltração, onde o solo é solto e permanentemente úmido. A espécie vive numa faixa de 1.500 a 2.650 m de altitude sendo uma planta altiplana ou sub-alpina. Devido à sua distribuição localizada, N. Rajah é classificada como uma espécie em perigo pela IUCN e listado no Anexo I do CITES.
Inicialmente exemplares foram coletados por Hugh Low no monte Kinabalu em 1858, e descrito no ano seguinte, por Joseph Dalton Hooker, que o nomeou de James Brooke, o primeiro rajá branco de Sarawak, Índia. Hooker chamou de "uma das plantas descobertas mais marcantes".[2] Desde que foi introduzido para o cultivo em 1881, N. Rajah sempre foi uma das mais procuradas. Por um longo tempo, a planta era raramente vista em coleções particulares, devido à sua raridade, preço e exigências especiais crescentes. No entanto, recentes avanços em tecnologia de cultura de tecidos resultaram na queda dos preços dramaticamente, e N. Rajah é agora relativamente difundida no cultivo.
N. Rajah é mais famosa pela sua trepadeira em forma de jarro, que pode crescer até 35 cm de altura e 18 cm de largura.[1] Esta planta consegue absorver 3,5 litros de água [3] e 2,5 litros de líquido digestivo, tornando-se, provavelmente, o maior do gênero em volume. Outra característica morfológica do N. Rajah é a penhora de folhas peltadas de lâmina e gavinha, que está presente em apenas algumas outras espécies.
A planta pode ocasionalmente prender pequenos vertebrados e até pequenos mamíferos, como ratos, enganados nas armadilhas em forma de jarro[4]. É uma das duas únicas espécies de Nepenthes documentadas como capturadores de insetos, pequenos vertebrados, como sapos, lagartos e até mesmo aves e mamíferos, a outra é Nepenthes rafflesiana.
Outra característica fundamental do N. Rajah é a relativa facilidade com que pode se hibridizar na natureza.[5] Híbridos entre elas e todas as outras espécies de Nepenthes no monte Kinabalu foram registrados. No entanto, devido ao crescimento natural lento da N. Rajah, alguns híbridos foram artificialmente produzidos por enquanto.
Nepenthes Rajah é uma planta carnívora da família das nepentáceas. É endêmica do Monte Kinabalu e também do Monte Tambuyukon em Sabah, Bornéu. N. Rajah cresce exclusivamente sobre substratos de serpentina, particularmente em áreas de infiltração, onde o solo é solto e permanentemente úmido. A espécie vive numa faixa de 1.500 a 2.650 m de altitude sendo uma planta altiplana ou sub-alpina. Devido à sua distribuição localizada, N. Rajah é classificada como uma espécie em perigo pela IUCN e listado no Anexo I do CITES.
Inicialmente exemplares foram coletados por Hugh Low no monte Kinabalu em 1858, e descrito no ano seguinte, por Joseph Dalton Hooker, que o nomeou de James Brooke, o primeiro rajá branco de Sarawak, Índia. Hooker chamou de "uma das plantas descobertas mais marcantes". Desde que foi introduzido para o cultivo em 1881, N. Rajah sempre foi uma das mais procuradas. Por um longo tempo, a planta era raramente vista em coleções particulares, devido à sua raridade, preço e exigências especiais crescentes. No entanto, recentes avanços em tecnologia de cultura de tecidos resultaram na queda dos preços dramaticamente, e N. Rajah é agora relativamente difundida no cultivo.
N. Rajah é mais famosa pela sua trepadeira em forma de jarro, que pode crescer até 35 cm de altura e 18 cm de largura. Esta planta consegue absorver 3,5 litros de água e 2,5 litros de líquido digestivo, tornando-se, provavelmente, o maior do gênero em volume. Outra característica morfológica do N. Rajah é a penhora de folhas peltadas de lâmina e gavinha, que está presente em apenas algumas outras espécies.
A planta pode ocasionalmente prender pequenos vertebrados e até pequenos mamíferos, como ratos, enganados nas armadilhas em forma de jarro. É uma das duas únicas espécies de Nepenthes documentadas como capturadores de insetos, pequenos vertebrados, como sapos, lagartos e até mesmo aves e mamíferos, a outra é Nepenthes rafflesiana.
Outra característica fundamental do N. Rajah é a relativa facilidade com que pode se hibridizar na natureza. Híbridos entre elas e todas as outras espécies de Nepenthes no monte Kinabalu foram registrados. No entanto, devido ao crescimento natural lento da N. Rajah, alguns híbridos foram artificialmente produzidos por enquanto.
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