Nepenthes rafflesiana

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iNepenthes rafflesiana

Upper pitcher of N. rafflesiana. Bako National Park, Borneo.

Conservation status

Least concern (LR/lc)

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Caryophyllales
Family:	Nepenthaceae
Genus:	Nepenthes
Species:	N. rafflesiana

Binomial name

Nepenthes rafflesiana
Jack (1835)

Nepenthes rafflesiana (after Stamford Raffles, founder of Singapore) is a species of pitcher plant. It has a very wide distribution covering Borneo, Sumatra, Peninsular Malaysia and Singapore. N. rafflesiana is extremely variable (second only to N. mirabilis) with numerous forms and varieties described. In Borneo alone, there are at least four distinct varieties. The most impressive form, known as N. rafflesiana f. gigantea, produces enormous pitchers rivaling those of N. rajah in size.

1 Biology
2 Cultivation
3 Forms and varieties
4 Conservation
5 Gallery
6 References

[edit] Biology

Ant drinking nectar from the peristome of a N. rafflesiana pitcher

N. rafflesiana is found in tropical lowlands. It produces two distinct types of pitchers (heavily modified leaves), which are used to capture and kill insect prey for nutrients. The lower pitchers are generally round, squat and 'winged', while the upper pitchers are more narrow at their base. The species is widely variable and comes in a variety of shapes and colors - most contain varying amounts of green, white, and maroon streaks. All Nepenthes are passive carnivores with no moving parts, unlike their distant cousins the Venus flytrap. N. rafflesiana kills by luring its prey into its pitchers, whose peristomes secrete a sweet-tasting nectar. Once the insect is inside, it quickly finds the walls of the pitcher too slippery to scale and drowns. Digestive enzymes released by the plant into the liquid break down the prey and release soluble nutrients, which are absorbed by the plant through the walls of the pitcher. The carnivorous nature of Nepenthes is supposedly a consequence of living in nutrient-poor soils; since the main method of nutrient absorption in most plants (the root) is insufficient in these soils, the plants have evolved other ways to gain nutrients. As a result, the roots of Nepenthes and most other carnivorous plants are slight and fragile; hence care must be taken when repotting. All Nepenthes are dioecious, meaning that each individual plant has only male or female characteristics.

[edit] Cultivation

Plant cultivated in Kuching, Sarawak

N. rafflesiana is very popular in cultivation; it is a lowland Nepenthes (enjoying hot, humid conditions most of the time, as found in tropical jungle lowlands) but can be grown as an intermediate, with cooler nights and less humidity. It is a comparatively hardy Nepenthes that is commonly recommended as a "first plant" to new Nepenthes growers. The plant should be grown in shaded conditions, diffuse sunlight, or in a large grow chamber under artificial lights. Watering and misting should be performed frequently, and preferably with distilled water, to avoid mineral build-up that is not only unsightly but that may damage the delicate roots of Nepenthes (and most other carnivorous plants). Standing water is inadvisable. A wet, well-draining potting medium is a necessity. Methods of feeding are varied - some growers feed freeze-dried bloodworms or Koi pellets (both available in the fish section of most pet stores); others prefer orchid mixes. No carnivorous plant should ever be fed mammalian meat - this will result not only in an unpleasant smell but also the probable rotting of the pitcher and potential death of the plant. The digestive enzymes present have not evolved to handle large prey items, and the rotting material gives opportunistic bacteria and fungi a chance to take hold.

[edit] Forms and varieties

N. rafflesiana

"var. typica (Beck.)"
- f. elongata
- f. gigantea
- f. nivea (Hook. f.)
- f. nigropurpurea (Mast.)
- f. green
var. alata (Adam & Wilcock)
var. longicirrhosa (Tamin & Hottta)

[edit] Conservation

N. rafflesiana growing with Dischidia sp.

All wild populations of Nepenthes, including N. rafflesiana, are endangered due to habitat destruction and (to a lesser extent) poaching. N. rafflesiana is currently listed as a CITES Appendix I plant, so it does have some international trade restrictions (though not an outright ban). Thankfully, most N. rafflesiana plants on the market today are propagated by tissue culture or other forms of vegetative propagation. When puchasing any plant, especially those protected by CITES, it is important to ask the vendor about the plant's provenance.

[edit] Gallery

N. rafflesiana f. nivea	N. rafflesiana f. nivea in natural habitat	Upper pitcher	Insect prey caught by N. rafflesiana
Large lower pitcher	Newly opened lower pitcher	Plant with red leaves	Plant with winged tendrils, Bako National Park
Upper pitcher, Bako N. P.	Upper pitcher, Bako N. P.	Upper pitcher, Bako N. P.	Lower pitcher, Bako N. P.
N. rafflesiana growing in full sun, Bako National Park	Cultivated plant from Kuching	Cultivated plant	N. rafflesiana var. alata