The species was collected by Hugh Low on Mount Kinabalu in 1858, and described the following 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.