Nepenthes bicalcarata Hook.f.

First published in Candolle, Prodr. 17: 97 (1873)
This species is accepted
The native range of this species is NW. Borneo. It is a liana and grows primarily in the wet tropical biome.


Kew Species Profiles

General Description

Nepenthes bicalcarata is a pitcher plant from Borneo with two, distinctive fang-like structures that emerge below the lid of each pitcher. The specific epithet bicalcarata derives from the Latin bi, meaning two, and calcaratus, meaning spurred. In 1880 British explorer Frederick Burbidge described these protrusions as 'walrus-tooth-like prickles' and likened them to rat-traps.

Early speculation over the function of the spurs included the suggestion that they may deter insectivorous mammals such as tarsiers from removing insects from inside the pitchers. Now it is thought likely that the nectar that accumulates on their tips attracts insects, which then fall off the spurs into the pitcher fluid below.

In addition to feeding on captured and digested insects, N. bicalcarata also obtain nutrients through a mutually beneficial relationship with a species of ant living inside its tendrils.

Species Profile
Geography and distribution

Nepenthes bicalcarata is native to Borneo, where it is found in northwest Kalimantan, Sarawak, Brunei and southwestern Sabah.

It is locally common in peat-swamp forest and sometimes also occurs in heath forest on white sandy soils. It has been found at up to 950 m above sea level.


Overview: A terrestrial climber up to 15 m tall. Stem circular in cross-section, about 2 cm in diameter.

Leaves: Thin and stiff, up to 65 × 14 cm. Petiole (leaf stalk) up to 12 cm long, narrowly winged. Nectaries usually present on lower surface of petiole, next to stem. Ten or more longitudinal nerves on each side of midrib.

Pitchers (modified parts of leaves): Greenish orange, with orange to red flush from the covering of hairs. Peristome (collar around the opening) green, rarely red. Lid yellowish above, marbled deep red or purple below.

Lower pitchers up to 13.0 × 6.5 cm with two fringed wings. Nectaries scattered across surface of pitcher. Peristome up to 2 cm wide, ribbed, inner margin with teeth about 0.6 mm long. The uppermost 10-12 ribs are drawn out into a pair of downward curving, sharply pointed thorns up to 2.5 cm long. Lid kidney-shaped. Tendril swollen, up to 12 mm thick, with a thin-walled spot facing the pitcher surface that is often hollowed out and inhabited by ants.

Upper pitchers up to 13 × 6 cm, with two prominent ribs. Lid up to 4 × 10 cm. Tendril once-coiled.

Male flowers: Tepals deep purple to blackish, 5 × 4 mm, borne in clusters of up to 15 flowers on inflorescences up to 1 m long.

Female flowers: Borne on inflorescences that are shorter than the male inflorescences.

Fruits: Capsules with valves to 3.0 × 0.5 cm. Seeds not yet recorded.

Carnivorous lifestyle

Insects are believed to be attracted to nectar produced by large glands covering the pitchers, especially on the lower surface of the pitcher lid. The ridged and toothed edge (peristome) of the pitcher makes it difficult for any animals that fall in to climb back out. They usually die inside the pitcher, drowning in the liquid secreted in its lower half, where they are then broken down by digestive enzymes into nutrients that become available for use by the plant.

Unusual relationship with ants

Pitchers of Nepenthes bicalcarata often have a swollen tendril with a thin-walled spot that is sometimes hollowed-out and inhabited by ants. These ants ( Camponotus schmitzi ) benefit not only from a nesting space, but also obtain nutrition from extrafloral nectar and by recovering prey items from pitcher fluid.

Fanged pitcher plant is thought to benefit from this relationship in a number of ways. The ants may fend off herbivores and animals seeking to remove prey items from the pitchers. By removing and consuming large, indigestible prey items they may also protect pitchers from putrefaction. Additionally, research has found that these ants regularly clean the surface of the peristome (collar around the opening of the pitcher). This cleaning increases the prey capture efficiency (by keeping the peristome smooth) and extends the life of the pitcher (it remains functional for longer and hence does not need to be replaced by energy-expensive new growth).

Threats and conservation

Nepenthes bicalcarata is locally common in peat-swamp forest in parts of Borneo but has been assessed as Vulnerable (VU) according to IUCN Red List criteria.

Nepenthes species are listed on CITES Appendix II, meaning that trade in wild collected plants is subject to controls.


Nepenthes species are cultivated worldwide by carnivorous plant enthusiasts.


Nepenthes bicalcarata is cultivated in the Tropical Nursery (one of the behind-the-scenes areas) at Kew.

The Nepenthes collection is one of the few for which Kew still uses a small amount of peat. A coir-based mix has been tested but was not suitable and hence a perlite and peat mix is used. Kew is committed to reducing its use of peat even further and is trialling a range of alternatives from pure Seramis (expanded clay particles) to finely chipped bark.

Plants are kept at 20-24°C during the winter and vents are opened if the temperature reaches 26°C in the summer. They are misted daily (but only on sunny days during the winter), twice daily during the summer. Plants benefit from the strong light of a south-facing position and small weekly feeds of liquid fertiliser.

This species at Kew

Nepenthes bicalcarata can be seen growing in the Tropical Carnivorous Zone of Kew's Princess of Wales Conservatory (Zone 8).

This newly redeveloped zone is home to many other species including Nepenthes truncata , N. rafflesiana , N. vietchii and the recently described N. robcantleyi . Growing alongside these are Amorphophallus paeoniifolius and A. variabilis .

Dried and alcohol-preserved specimens of Nepenthes bicalcarata are held in Kew's Herbarium, where they are available to researchers from around the world, by appointment. Details of some of these specimens, including images, are available online in Kew's Herbarium Catalogue.


Leaves, pitchers and a stem of Nepenthes bicalcarata collected by British explorer Frederick Burbidge (1847-1905) are held in Kew's Economic Botany Collection, where they are available to researchers, by appointment.

Kew's work on Asian pitcher plants

Kew has a long tradition of work on Nepenthes . Joseph Hooker, a former Director of Kew, completed the first revision of this genus and described many of the world's most spectacular species.

Kew's micropropagation unit pioneered development of cultures from seed in the 1970s and 1980s. Species such as Nepenthes rajah , which had been highly threatened by the collection of plants from the wild, became widely available through subsequent tissue culture work carried out by various nurseries.

Peat-swamp forest and less commonly in heath forest.
Vulnerable (VU) B1+2c according to IUCN Red List criteria.

Small mammals and reptiles may drown, and then be digested, if they fall into the large pitchers of this species.


IUCN Red List of Threatened Species

VU - vulnerable


Cultivated as an ornamental by carnivorous plant enthusiasts.

Common Names

Fanged pitcher plant


  • Herbarium Catalogue Specimens

    • Digital Image © Board of Trustees, RBG Kew
  • IUCN Categories

    • IUCN Red List of Threatened Species
  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at and
    • © Copyright 2023 World Checklist of Vascular Plants.
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at and
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants.
  • Kew Species Profiles

    • Kew Species Profiles