Fanged pitcher plant (Nepenthes bicalcarata)
|Size||Pitcher height: up to 25 cm (2)|
Pitcher width: up to 16 cm (2)
Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3).
The tropical pitcher plants (Nepenthes) of Asia are amongst the largest and most spectacular of all carnivorous plants (4), being equipped with large, modified, pitcher-shaped leaves with which to trap and digest small organisms (5). These deadly traps hang from coiled tendrils, and are filled with acidic digestive juices. In order to prevent the digestive liquid from being diluted by rainwater, the pitchers are covered by small lids as they grow, which open up when the pitchers are fully developed (5). One of the most striking of all Nepenthes is the fanged pitcher plant, a large and impressive species famous for the two menacing fang-like spines projecting downward from its lid (6), which distinguish it from any other Nepenthes species (2). The pitcher colour of this species is typically yellowish green or orange, and occasionally red (7).
Found only on the island of Borneo, in Brunei Darussalam, Kalimantan (Indonesia), and Sabah and Sarawak (Malaysia) (1).
Commonly found in peat-swamp forest and occasionally in sandy heath forest, from sea-level to 950 metres above sea level (1) (7).
Nepenthes pitcher plants have evolved carnivorous habits as the answer to growing in extremely nutrient-poor habitats (2) (5). The plants are able to break down and absorb nitrogen and other nutrients from animals, usually invertebrates such as insects, that fall into the pitchers. This supplements any nutrition gained from the soils and therefore allows these plants to survive where others may not. Nepenthes plants attract their prey with nectar, aromas and visual signals such as colour (5). The brim of the pitcher, the peristome, produces the highest amount of nectar, and animals stepping on the slippery, waxy surface of the peristome often fall in. There, unable to escape, they drown in the pitcher fluid and their bodies are broken down by digestive enzymes (2).
Like many Nepenthes species, the fanged pitcher plant has also developed a mutualistic relationship with insects. The ant Camponotus schmitzi nests in the hollow tendrils of the plant, and is able to run up and down the walls of the pitchers without falling in, enabling it to hunt in the pitcher fluid (2) (4). In an unusual twist, these ants help the fanged pitcher plant not by feeding it, but by removing some of its larger prey. When pitcher plants catch large insects or other large prey, the animal can begin to decay before being digested, and this putrefaction can spread to the pitcher and shorten its lifespan. The ants specifically haul out these larger items from the pitcher, breaking them into smaller pieces to feed upon, and thereby also benefit from this strange relationship (4).
Nepenthes are dioecious, meaning that there are separate male and female plants. Likely pollinators include flies, moths, beetles, bugs and ants, which have all been observed visiting the flowers. The fruit takes around three months to develop, and can contain 500 or more seeds, which are very light and have long wings, and are carried by the wind to aid dispersal (2).
The main threat to tropical pitcher plants (Nepenthes) is habitat destruction. However, as popular ornamental plants, they are also widely collected from the wild, and due to their low population numbers, commercial collection and illegal trade has had a serious impact (5).
All Nepenthes species are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which restricts the legal trade of these plants. Methods have also been developed to produce tropical pitcher plants from tissue culture, and the horticulture and cultivation of plants produced by this process may significantly help reduce the impact on wild populations (5).
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- Carnivore: flesh-eating.
- Mutualistic relationship: relationship in which two organisms form a close association that benefits both organisms.
IUCN Red List (December, 2009)