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Giant Pitcher Plant (Rajah Brooke's Pitcher Plant)
Nepenthes rajah
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Taxonomy
| Family: | Nepenthaceae |
|---|---|
| Genus: | Nepenthes |
| Order: | Caryophyllales |
Overview
Nepenthes rajah is a highland tropical pitcher plant endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Malaysian Borneo. Its urn-shaped pitchers, up to 41 cm tall and able to hold 3.5 liters of water, are probably the largest in the genus.
Nepenthes rajah is a scrambling vine whose stem usually runs along the ground, climbing whenever it finds support. The stem is up to 30 mm thick and may reach 6 m, though it rarely exceeds 3 m. The large, leathery leaves have wavy margins and are peltate: the tendril joins the underside of the blade a short distance before its tip.
Lower pitchers, the most common kind, rest on the ground. They are ovoid, usually red to purple outside and lime green to purple inside, and exceptional ones are over 40 cm long, holding 3.5 L of water and more than 2.5 L of digestive fluid, although most hold no more than about 200 ml. The peristome is greatly expanded, with a scalloped edge and raised ribs ending in short, sharp teeth. The huge vaulted lid is a distinguishing feature. Mature plants may also make much smaller, funnel-shaped upper pitchers, but these are rare because the stems seldom grow long.
Plants are male or female. The inflorescence can be 80 cm tall, sometimes 120 cm, with brownish-yellow flowers reported to smell strongly sweet. N. rajah hybridizes with every other Nepenthes species that grows with it.
Geographic Information
Native Region: Mount Kinabalu and Mount Tambuyukon, Sabah, Malaysian Borneo (endemic)
Climate Zones: Tropical upper montane (1,500-2,650 m); cultivated under glass as a highland species
N. rajah grows only on serpentine (ultramafic) soils, rich in nickel and chromium, at 1,500-2,650 m (4,920-8,690 ft), particularly where ground water seeps and the soil is loose and permanently moist. It grows in open areas exposed to direct sun. At the top of its range night temperatures may approach freezing and days rarely exceed 25°C (77°F), and humidity rises from 65-75% by day to over 95% at night. The popular story that it grows only in the spray of waterfalls is a misconception. The Mesilau Nature Resort is now the only place where visitors can see it in the wild.
Physical Characteristics
Mature Size: Pitchers up to 41 cm (16 in) tall and 20 cm (8 in) wide; stem up to 6 m, usually under 3 m
Growth Rate: Slow
Trap Type: Pitfall Trap
Insects, especially ants, make up most of the prey in both lower and upper pitchers. The pitchers are large enough to drown small vertebrates, and drowned rats have been recorded, but these catches are rare and probably involve sick animals or animals seeking water.
N. rajah also has a mutualistic relationship with small mammals. The underside of the lid secretes a sweet exudate. Mountain treeshrews (Tupaia montana) by day and summit rats (Rattus baluensis) at night lick it and leave droppings in the pitcher, which are thought to supply most of the nitrogen the plant needs. Wells and colleagues (2011) filmed visits about once every 4.2 hours and identified 44 volatile compounds in the lid secretions, typical of sweet fruit and flower scents. The distance from the lid glands to the front of the mouth matches the head and body length of a treeshrew.
Care Guide
Light Requirements
Bright light. In the wild it grows in open areas in direct sun. In the tropics growers can use natural sunlight; elsewhere a bright greenhouse or strong artificial light.
About 12 hours, comparable to the tropics daily
Water Requirements
Type: Purified water recommended; it can tolerate hard water
Method: Water from above to keep the mix evenly moist, as in the seepage areas where it grows, and let it drain. Do not leave the pot standing in water.
Frequency: Keep the mix constantly moist
Humidity: About 75% or more
Soil
A 50:50 mix of long-fiber sphagnum moss and perlite is a good starting point. Use a wide pot, as the plant makes an extensive root system.
pH: Acidic (sphagnum based)
Temperature
Summer: Days 77-86°F (25-30°C), nights 50-59°F (10-15°C)
Winter: Same as summer; cool nights all year
Feeding
Frequency: Micronutrient solutions only; avoid NPK fertilizers
Trials by a commercial nursery found micronutrient solutions beneficial, while fertilizers containing nitrogen, phosphorus and potassium (NPK) were damaging.
Propagation
Methods: Plants in the trade are produced by tissue culture (in vitro propagation), generally started from seed. Seed requires a male and a female plant flowering at the same time; it is short-lived and should be sown immediately. Stem cuttings of about two leaves each can be rooted in very high humidity, though some Nepenthes take several months to root.
Difficulty: Difficult
Beginner Tips
This is not a houseplant. Start with a tissue-cultured seedling only if you can provide cool nights, high humidity and strong light all year.
Troubleshooting
Plant stalls or declines: check that nights are cool enough for a highland species. Leaf edges burning and no new pitchers: humidity too low. Damage after feeding with fertilizer: stop using NPK products.
Growing Tips
Go easy on fertilizer Troubleshooting
Nursery trials found micronutrient solutions helpful but NPK fertilizers damaging. If leaves or pitchers suffer after feeding, stop.
Give the roots room General
It forms an extensive root system, so choose a wide pot rather than a tall narrow one.
Night cooling is essential Advanced
N. rajah comes from 1,500-2,650 m on Kinabalu, where nights can approach freezing. Aim for days of 25-30°C and nights of 10-15°C.
Interesting Facts
It is named after James Brooke, the first White Rajah of Sarawak, and is often called the 'King of Nepenthes'.
Two mosquitoes, Culex rajah and Toxorhynchites rajah, were named after it in 1989; their larvae live in its pitchers.
Its pollen can be carried as far as 10 km.
It is listed on CITES Appendix I, added in 1981 after poaching depleted wild populations.
Malaysia featured it on a postage stamp in 1996.
The IUCN Red List classes it as Endangered (Clarke et al., 2000, assessment T39690A10251581).
History
Hugh Low collected the species on Mount Kinabalu in 1858, and Joseph Dalton Hooker described it the next year in The Transactions of the Linnean Society of London. Spenser St. John, who accompanied Low, gave an account of it in his 1862 Life in the Forests of the Far East, including a drowned rat in a pitcher.
Frederick William Burbidge collected it for the Veitch Nurseries in 1878, and it entered cultivation in 1881, becoming much sought after by Victorian growers. In 1882 Veitch exhibited it at the Royal Horticultural Society's show, where it won a first class certificate; in 1889 it was priced at £2 2s a plant. Its needs proved too hard to meet, and by 1905 the Veitch plants were gone. Tissue culture has since made it widely available at modest prices, largely removing the incentive to collect wild plants.
Sources
- Nepenthes rajah, Wikipedia
- Nepenthes: species of Borneo, The Carnivorous Plant FAQ (Barry Rice)
- Chin, Moran & Clarke (2010), Trap geometry in three giant montane pitcher plant species from Borneo is a function of tree shrew body size, New Phytologist 186: 461-470
- Wells, Lakim, Schulz & Ayasse (2011), Pitchers of Nepenthes rajah collect faecal droppings from both diurnal and nocturnal small mammals and emit fruity odour, Journal of Tropical Ecology 27: 347-353
- Nepenthes: basic cultivation, The Carnivorous Plant FAQ (Barry Rice)
- Nepenthes: advanced cultivation, The Carnivorous Plant FAQ (Barry Rice)
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