Fascinating Nepenthes of Borneo
By Patricia Hului
Broadcaster and naturalist Sir David Attenborough has lent his voice to many natural history programmes for the last six decades.
With a long list of achievements, one would find it hard to keep up with Attenborough’s contributions, particularly in terms of his environmental advocacy. One of his responsibilities includes being patron to International Union for Conservation of Nature- Carnivorous Plant Specialist Group (IUCN-CPSG).
It is a group of volunteers helping in the conservation of all genera of carnivorous plants.
The Nepenthes or our local tropical pitcher plant happens to be one of them.
Known widely for its unique and fascinating characteristic features, Nepenthes comes in a great diversity of colours, growth forms, and pitcher shapes, making them attractive both to collectors and researchers interested in their ecology.
Over 150 species are recognised under this genus to date, ranging widely throughout Southeast Asia, with the peak of their speciation centered in Sumatra, Borneo, and the Philippines.
During a talk organised by Sarawak Biodiversity Centre (SBC) on Jan 16 at Telang Usan Hotel, one of IUCN-CPSG volunteers Ch’ien C Lee shared the fascinating discoveries of Nepenthes in Borneo to some 100 members of the public.
Recent discoveries have revealed that although once believed to be purely carnivorous, some Nepenthes have specialised to exploit other means of acquiring food.
According to Lee who is also the co-author of ‘Pitcher Plants of Borneo’, Nepenthes do not necessary catch every insect that visits them.
“In fact, when you look at it at from an ecological perspective, ants maybe sacrifice 10 per cent of their workers to the plant.”
In return, the other 90 per cent that visit the plant take back valuable nectar.
Meanwhile, the plant gives away nectar they generate for free from sunlight, water and carbon dioxide and they get from the ants, important nutrients.
“When you look at it from this perspective, it is more like a mutualistic relationship between some of the plants and insects, particularly social insects.”
Lee added that insects are great little packages of food; they are full of protein, lots of nitrogen but insects are not the only source of nutrients out in the forest.
“Plants have been exploiting other ways to get nutrients, through leaf litter for example.”
Lee took Nepenthes ampullaria which is part detritivore, collecting and digesting falling leaf litter in their pitches as an example.
Additionally, Nepenthes also have mutualistic relationships with animals like mountain tree-shrews.
Mountain tree-shrews are attracted to the nectar found under the surface of the Nepenthes lowii’s lids.
This tropical pitcher plant endemic to Borneo was named after Sir Huge Low who first found it on Mount Kinabalu.
While it’s collecting nectar, the animal would eventually excrete its dropping into the pitchers. Nepenthes lowii is almost fully relying on mountain tree-shrews’ droppings for its source of nutrients.
“What could be better source of nutrients than animal droppings?”
Mountain tree-shrews also visit another endemic species of nepenthes on Mount Kinabalu– Nepenthes rajah which is named after James Brooke.
But by visiting Nepenthes rajah, mountain tree-shrews have different outcomes from paying a visit to Nepenthes lowii.
“These pitchers (Nepenthes rajah) are so large that sometimes a tree-shrew might fall inside. It has actually been found that this type occasionally eats small mammals including mountain tree-shrews.”
Threats and conservation of Nepenthes
When it comes to threats to Nepenthes, Lee said it was fortunate that Nepenthes grow in unusual habitats such as mountain summits, rocky cliffs and degraded soils.
“And because of these; they are spared from the majority of habitat loss that we see in Borneo due to logging and oil palm plantations.”
He added that these problems do not usually affect Nepenthes population directly.
The other more important threat for pitcher plant is plant poaching or illegal collection.
Lee shared that plant poaching or illegal collection was not much of a problem 20 years ago when there were not so many people who had a huge interest in pitcher plants.
Then there was a huge surging interest in pitcher plants as ornamentals and people started to grow them in green houses to collect all the different species.
“This interest has resulted in a lot of problems.”
Lee cited one example which happened in Mount Santubong which used to have beautiful pitcher plants growing at the summit.
“Maybe 12 years ago, they were completely collected out. The species is not going to go extinct but population can get wiped out by collectors.”
He explained that the species could be vulnerable to collectors if they can only grow on one single mountain.
A good side to the surging interest and popularity of the pitcher plants in horticulture is that there are now a lot of nurseries propagating plants.
“This has the potential to reduce the demand for wild collected plants. In fact you’ll see a lot of trade shows now have propagated plants for sale.”
Lee said that there were flowers shows in Malaysia which only used to have bonsai and orchids, now they have carnivorous plants section.
“If you enjoy growing them, make sure that you always getting them from reputable source that artificially propagating them.”
Lee also highlighted the importance of Nepenthes for eco-tourism in which many people came all the way just to see them in the wild.
“People love to see the plants in their native habitats.”
In other conservation efforts of pitcher plants, Lee asked the members of the public to report illegal plant poaching and support protection agencies and research such as IUCN-CPSG.
All the Nepenthes are protected plants in Sarawak and under Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).