Nepenthes × trusmadiensis (icon; after Mount Trus Madi

Mount Trus Madi

Mount Trus Madi or Trusmadi is Malaysia's second highest mountain at . It lies in the state of Sabah, close to Mount Kinabalu. The mountain supports a wide range of unique flora and fauna, perhaps most notably Nepenthes macrophylla, a species of pitcher plant.The natural hybrid Nepenthes ×...

), or the Trus Madi Pitcher-Plant, is a natural hybrid of two famous Bornean

Borneo

Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

 pitcher plant

Pitcher plant

Pitcher plants are carnivorous plants whose prey-trapping mechanism features a deep cavity filled with liquid known as a pitfall trap. It has been widely assumed that the various sorts of pitfall trap evolved from rolled leaves, with selection pressure favouring more deeply cupped leaves over...

 species: N. lowii

Nepenthes lowii

Nepenthes lowii , or Low's Pitcher-Plant, is a tropical pitcher plant endemic to Borneo. It is named after Hugh Low, who discovered it on Mount Kinabalu...

and N. macrophylla

Nepenthes macrophylla

Nepenthes macrophylla , the Large-Leaved Pitcher-Plant, is a tropical pitcher plant known only from a very restrictive elevation on Mount Trus Madi in Sabah, Malaysian Borneo...

. It is restricted to Mount Trus Madi

Mount Trus Madi

Mount Trus Madi or Trusmadi is Malaysia's second highest mountain at . It lies in the state of Sabah, close to Mount Kinabalu. The mountain supports a wide range of unique flora and fauna, perhaps most notably Nepenthes macrophylla, a species of pitcher plant.The natural hybrid Nepenthes ×...

, where both of its parent species are sympatric.

Botanical history

Nepenthes × trusmadiensis was discovered by Johannes Marabini and John Briggs in 1983. It was described the same year by Marabini. Briggs wrote the following account of its discovery:

We were about to leave the summit around 8.00 a.m. when Johannes Marabini emerged from a dense bush [...] holding two huge pitchers quite unlike any other species. The most striking feature was the sheer size of the pitchers—they were bigger than anything else on Trus Madi. Later on, we were to realise that they were the second biggest pitchers of all the Borneo Nepenthes—exceeded only by those of N. rajah

Nepenthes rajah

Nepenthes rajah is an insectivorous pitcher plant species of the Nepenthaceae family. It is endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Malaysian Borneo. Nepenthes rajah grows exclusively on serpentine substrates, particularly in areas of seeping ground water where the...

on Kinabalu

Mount Kinabalu

Mount Kinabalu is a prominent mountain on the island of Borneo in Southeast Asia. It is located in the East Malaysian state of Sabah and is protected as Kinabalu National Park, a World Heritage Site. Kinabalu is the tallest peak in Borneo's Crocker Range and is the tallest mountain in the Malay...

. [...] The evidence strongly suggested the new pitcher-plant was a hybrid of N. lowii and N. edwardsiana

Nepenthes edwardsiana

Nepenthes edwardsiana , or the Splendid Pitcher-Plant, is a tropical pitcher plant endemic to Mount Kinabalu and neighbouring Mount Tambuyukon in Sabah, Malaysian Borneo...

. The great size of the pitchers agreed with this idea—being characteristic of hybrids. There was no time to investigate the distribution of this new plant. So, after collecting a few specimens we set off down the mountain for the three-day trek back to Tambunan.

Description

Nepenthes × trusmadiensis has petiolate leaves measuring up to 50 cm in length. The pitchers of this hybrid are some of the largest of any Bornean Nepenthes species, reaching 35 cm in height. They are roughly intermediate in form between those of its parent species. The lid is held away from the mouth as in N. lowii and bears short britles on its lower surface. The peristome has prominent ribs and teeth, but is not as developed as that of N. macrophylla. The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 of N. × trusmadiensis may be up to 50 cm long and has two-flowered pedicels

Pedicel (botany)

A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....

. Despite the size of the pitchers, this hybrid is not large in stature.

Ecology

Nepenthes × trusmadiensis is restricted to the summit ridge of Mount Trus Madi and has been recorded from elevations of 2500 to 2600 m above sea level.