Nepenthes bicalcarata (/nɪˈpɛnθiːz baɪˌkælkəˈrɑːtə, - bɪˌkælkəˈreɪtə/; from Latin for "two-spurred"), also known as the fanged pitcher-plant,[4] is a tropical pitcher plant endemic to northwestern Borneo, Indonesia.

[5] Nepenthes bicalcarata was formally described by Joseph Dalton Hooker in his 1873 monograph, "Nepenthaceae", based on specimens collected by Hugh Low and Odoardo Beccari near the Lawas River in Borneo.

[3][7] This specimen is also held at the Royal Botanic Gardens, Kew[6] and a duplicate is deposited at the National Herbarium of the Netherlands in Leiden.

[11] Nepenthes bicalcarata was introduced to Europe in 1879 by British explorer Frederick William Burbidge, who collected plants for the famous Veitch Nursery.

It is most common in the peat swamp forests of the western coast of the island, which stretch across Sarawak, Sabah, Kalimantan, and Brunei.

[11] Specimens growing in undisturbed peat swamp forest, where sunlight is greatly diffused and high humidity prevails, reach the largest dimensions.

[11] Nepenthes bicalcarata has a shallow root system that only penetrates the top layer of peat and leaf litter, to a depth of about 25 cm.

[4] Nepenthes bicalcarata is generally found below 300 m in altitude, although Johannes Gottfried Hallier reported a single collection in 1894 from between 700 and 950 m above sea level.

[20] The two thorns that give N. bicalcarata its name are unique to this species and bear some of the largest nectaries in the plant kingdom.

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.

[11][24] In an article published in 1982, Cliff Dodd speculated on the function of the thorns, but did not believe they play a role in prey capture.

[26] A similar trapping method is employed by the Sumatran endemic N. lingulata, which has a single filiform appendage positioned over the pitcher mouth.

[27] 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 is little or no conductive waxy zone.

When it is dry, the peristome is highly ineffective in catching insect prey, but when wetted, the capture rate increases more than three-fold.

[31] Based on their findings, the authors made the "tentative prediction" that the upper pitchers of N. bicalcarata are less successful at catching anthophilous (flower-visiting) prey than those of sympatric N. rafflesiana.

[31] Nepenthes bicalcarata plays host to an unusual species of ant that makes its nest in the plant's hollow tendrils.

Nepenthes bicalcarata is a myrmecotroph (ant-fed plant), obtaining nutrients from C. schmitzi in the form of egesta and, occasionally, ant remains.

[5] The ants increase nutrient retention in the pitchers by preying on infaunal flies, which would otherwise eventually leave their hosts and thereby act as kleptoparasites.

[45][46] At other times, the ants are very passive, remaining hidden under the inner peristome fold, presumably so as not to dissuade visitation by potential prey species.

[45] John Thompson has suggested that N. bicalcarata may be the only plant species that obtains nutrients through both insect capture and ant-hosting habits.

[47] Camponotus schmitzi is able to swim in the pitcher fluid using tripod-like leg coordination similar to that of terrestrial locomotion[48][49] and can remain submerged for up to 30 seconds.

[11][51] The ants have been observed to clean the peristome of fungal hyphae and other contaminants, thereby maintaining high trapping efficiency over the pitcher's lifespan.

[52][53] Research conducted by Dennis and Marlis Merbach has shown that C. schmitzi also benefits N. bicalcarata by protecting it from pitcher-destroying weevils of the genus Alcidodes.

The pitcher fluid of N. bicalcarata is also less viscoelastic than that of most Nepenthes species, and appears to lack functional digestive enzymes.

Indeed, plants not inhabited by C. schmitzi do not appear to benefit significantly from carnivory, with any gains from prey digestion being offset by the high costs of pitcher construction.

[59] Left centre: Effect of C. schmitzi occupancy on leaf apex abortion and pitcher production rates.

In the first chart (A), cases where the tendril was found to be cut are grouped under unknown fate (denoted with a question mark) and "pitcher" encompasses both living and dead traps (in non-pitchering plants, the latter).

Charles Clarke reported a single plant displaying characters intermediate between those of N. bicalcarata, N. rafflesiana and N. mirabilis var.

[11] Nepenthes bicalcarata may be cultivated in a similar manner to other members of the genus, though it requires relatively hot and humid conditions.

Under satisfactory conditions, this plant will grow quite fast for a Nepenthes, reaching a large size relatively rapidly.