Everything about Nepenthes Bicalcarata totally explained
Nepenthes bicalcarata (
Latin:
bi = two,
calcaratus = spur), also known as the
Fanged Pitcher-Plant, is a tropical
pitcher plant endemic to northwestern
Borneo.
Botanical history
N. bicalcarata was formally described by
Joseph Dalton Hooker in 1873, based on specimens collected by
Hugh Low and
Odoardo Beccari near
Lawas River in Borneo. The
type specimen,
Low s.n., is deposited at the
Royal Botanic Gardens, Kew. Seven years later,
Spencer Le Marchant Moore described
Nepenthes dyak, based on a specimen collected by
Johannes Elias Teijsmann,
Teijsmann 10962, from
Kapuas River near
Sintang in western Borneo. This specimen is also held at the Royal Botanic Gardens, Kew
N. dyak was later mentioned several more times in the literature, but is now considered conspecific with
N. bicalcarta.
"Then there's N. bicalcarata, a most robust habited kind with sturdy foliage and bag-like pitchers provided with a vicious-looking rat-trap-like apparatus in its lid which renders it very distinct from its neighbours."
Several years after its introduction,
N. bicalcarata was still very much a horticultural rarity. In Veitch's catalogue for 1889,
N. bicalcarata was priced at
£3.3
s per plant, while the famous giant-pitchered
N. northiana and
N. rajah were selling for £2.2s.
The leaves of
N. bicalcarata are and in texture. The is - in form and also reaches huge dimensions, growing to 80 cm in length and 12 cm in width. It is slightly on the stem, forming two narrow wings. The lamina has indistinct longitudinal veins and numerous veins.
Tendrils may be up to 60 cm long and 8 mm wide. They are hollow and swollen near the pitcher. Branches on the flower stem are up to 40 mm long and bear up to 15 flowers.
Sepals are either or and up to 4 mm long.
The
conservation status of
N. bicalcarata is listed as
Vulnerable on the
2006 IUCN Red List of Threatened Species based on an assessment carried out in 2000. In 1997,
Charles Clarke informally classified the species as
Near Threatened based on the
IUCN criteria.
Carnivory
The two thorns that give
N. bicalcarata its name are unique to this species and bear some of the largest
nectar glands in the plant kingdom. The purpose of these structures has long been debated among botanists.
Frederick William Burbidge suggested that they might serve to deter
arboreal mammals such as
tarsiers,
lorises and
monkeys from stealing the contents of the pitchers. In an article published in 1982, Cliff Dodd speculated on the function of the thorns, but didn't believe they play a role in prey capture.
Charles Clarke observed that monkeys and tarsiers rip the pitchers open at the sides in order to feed from them, rather than reaching in through the pitcher mouth. However, he found that the mammals attacked the pitchers of
N. bicalcarata less frequently than those of other species, such as
N. rafflesiana.
Together with
N. ampullaria and
N. ventricosa,
N. bicalcarata is unusual in that the glandular region of the pitcher extends almost to the peristome, such that there's little or no conductive waxy zone. The waxy zone functions by causing prey to slip and fall into the digestive fluid. A 2004 study found that the peristome of
N. bicalcarata plays a very important role in prey capture. When it's dry, the peristome is very ineffective in catching insect prey, but when wetted, the capture rate increases more than three-fold. This means that the peristome is less reflective than the pitcher cup in the violet and red bands, but more reflective in the green band. The contrast maxima in the green and blue regions seem to correspond to insect visual sensitivity maxima, while the others do not. Described as
Camponotus schmitzi in 1933, it's a member of the extremely populous and widespread genus of
carpenter ants.
This unique animal-plant interaction was noted by
Frederick William Burbidge as early as 1880. In 1904,
Odoardo Beccari suggested that the ants feed on insects found on and around the plant, but may fall prey to it themselves. In 1990, B. Hölldobler and E.O. Wilson proposed that
N. bicalcarata and
C. schmitzi form a
mutually beneficial association. At the time, however, no experimental data existed to support such a hypothesis. A series of observations and experiments carried out in
Brunei by
Charles Clarke in 1992 and 1998, and by Clarke and Kitching in 1993 and 1995, strongly support the
mutualism theory.
The ants feed by descending into the pitcher fluid and retrieving
arthropods caught by the plant. The ants seem to ignore smaller insects and only target larger prey items. Hauling food from the pitcher fluid to the peristome, a distance of no more than 5 cm, may take up to 12 hours.
Research conducted by Dennis and Marlis Merbach has shown that
C. schmitzi protect
N. bicalcarata against pitcher-destroying
weevils of the genus
Alcidodes.
The ants seem to favour upper pitchers and rarely colonise lower pitchers. This is likely due to the fact that terrestrial traps are periodically submerged in water during heavy rains. Flooding of the ants' nest chamber could result in the death of the developing eggs,
larvae, and
pupae.
A species of
mite,
Naiadacarus nepenthicola, appears to be restricted to the pitchers of
N. bicalcarata. It is thought to feed on decomposing leaves and insects that are caught in the pitchers.
Deutonymphs of this mite are dispersed through
phoresy on
C. schmitzi.
Natural hybrids
The following natural
hybrids involving
N. bicalcarata have been recorded.
N. ampullaria × N. bicalcarata
Pitchers bear the characteristic thorns of N. bicalcarata, although they're greatly reduced in size. The mouth is round and the lid is - in form. This hybrid resembles N. × hookeriana to a certain extent, but differs in having spines on the underside of the lid and more globose upper pitchers with a smaller lid.
N. bicalcarata has been artificially crossed with N. hirsuta. A particularly robust-pitchered cultivar of this hybrid was named Nepenthes 'Hortulanus Otten', in honour of Karel Otten, former curator of the Botanic Garden in Ghent, Belgium.
A cultivar of the artificial cross N. bicalcarata × N. × dyeriana was registered in 1988 under the name Nepenthes 'Nina Dodd'. It is named after a relative of Cliff Dodd, who created the hybrid.
Two further cultivars of manmade hybrids involving N. bicalcarata have been named. These are Nepenthes 'Bella' ((N. ampullaria × N. bicalcarata) × N. truncata) and Nepenthes 'Rapa' (N. ampullaria × N. bicalcarata). However, both of these names are not established, as they were published without a description.[Further Information]
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