"The specific epithet rajah means "King" in Malay and was named after Sir James Brooke, the Rajah of Sarawak. This large and splendid Nepenthes distinguishes itself by its peltate-tipped leaf and large pitcher with a deeply vaulted lid which is always larger than the pitcher mouth, N. rajah is rather fond of wet places like swamps or the surroundings of a water fall. Marai Parai plateau is well known as a habitat of this species. Recently other places mentioned above [the Mesilau-East River (near Mesilau Cave), the Upper Kolopis River and eastern slope of Mt. Tambuyukon] are recorded as new habitats."