Nepenthes rajah 

This species is native to Sabah (Mount Kinabalu and Mount Tamboyukon), in Malaysian Borneo. It occurs on moist, loose soils between 1,500 and 2,650 m above sea level.

Nepenthes rajah is considered to be an endangered species, due to its localised distribution. It is thought that most (or perhaps all) of the population occurs within a protected area. The species is currently listed on CITES Appendix I, meaning that trade in wild collected plants is effectively prohibited.

In the early 1980s, plants of Nepenthes rajah were first micropropagated at the Royal Botanic Gardens, Kew, where several novel techniques were devised to facilitate this. Most plants of N. rajah that are in trade today derive from micropropagated material, and the illegal trade in plants dug from the Kinabalu National Park, once the only source of supply, is thought to have ceased as a consequence.

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This species was introduced into cultivation in 1881, though was then lost for several decades before it was reintroduced. It has been in demand ever since this revival. Advances in tissue culture technology have helped make this species more widely available.

Images of Nepenthes rajah are also used in promotional material to support tourism in Sabah, and in particular in Kinabalu National Park in Borneo.

Nepenthes rajah is cultivated in the Tropical Nursery (one of the behind-the-scenes areas) at Kew, where propagules from the Micropropagation Unit are taken from glass jars and weaned into small rubberised pots. A peat/perlite mix is used as the species requires an acid soil.

Plants are kept warm during the day and cool at night (14 to 16 °C), and misted daily, or twice daily during the summer. Plants benefit from strong lighting, a south facing position and small weekly feeds. The large pitchers that occur in the wild do not currently develop on Kew-cultivated specimens. It is thought this may be the result of the process by which propagules have, over the past 30 years, been selected for suitability for micropropagation, and that the procurement of fresh material may remedy the situation.

The original specimens collected by Hugh Low on Mount Kinabalu in the 19th century, from which Joseph Hooker named the species, are preserved in the Kew Herbarium. The Herbarium is one of the behind-the-scenes areas of Kew, where preserved specimens are made available to bona fide researchers by appointment.

Kew has a large collection (about 200 accessions) of living Nepenthes, maintained for research and conservation purposes. Public access is available mainly through annual visits from the Carnivorous Plant Society. Nepenthes rajah is grown in the Tropical Nursery, one of the behind-the-scenes areas of Kew. It has proved difficult to cultivate plants with the giant pitchers that are seen in the wild, and further research is needed to find out why this is the case.

Kew staff (mainly with Matthew Jebb of Glasnevin Botanic Garden, Dublin) have described 12 new species of Nepenthes and co-authored accounts for identifying the Nepenthes of several areas in the last ten years: European Garden Flora, Flora of China, Flora Malesiana (covering SE Asia), Flora of Peninsular Malaysia (in press) and Flora of Thailand (in prep). A world monograph of the genus is in progress.

How Kew's Micropropagation Unit provides support for our Living Collections

Micropropagation at Kew - pdf download

Science & research at Kew - find out more about the work of our Wet Tropics (SE Asia) team

Kew Discoveries 2009 - new orchids discovered on Borneo's Mount Kinbalu

Carnivorous Plant Society website

Search Kew's databases for more information on this species