Posts on Flora

New Pitcher Plant Species from New Guinea

29 November 2013

It wouldn’t be far-fetched to say that we are presently experiencing a Golden Age of pitcher plant discovery. Scarcely 16 years ago there were 84 officially recognized species in the genus Nepenthes; now that total is fast approaching 150, with nearly 30 new taxa described in the past 5 years alone. Whilst most of these new taxa are only slight variations of previously described species or are ‘splits’ where a single taxon has been divided based on what are deemed significant differences, a few are unique and represent striking new forms (e.g. N. attenboroughii and N. undulatifolia).

Last month, whilst trekking through the mountains of Papua (Indonesian New Guinea) with longtime friend and colleague Dr. Charles Clarke, we were excited to encounter yet another undescribed species of Nepenthes on a remote forested ridge. Our 2-week expedition had been fraught with numerous setbacks, including illness and inter-tribal warfare which nearly thwarted our entire climb and ultimately prevented us from reaching the summit we had originally targeted. Nevertheless, we were able to explore some incredibly beautiful and pristine montane habitats and in a fortunate turn of luck, stumble across this new and distinctive species.

Because of this plant’s unique features, it’s taxonomic affinities with other Nepenthes, both within and outside of New Guinea, are not yet evident. The globose lower pitchers (below left) with their broad and strongly-toothed peristome, and the funnel-shaped upper pitchers (below right) bear little resemblance to other Papuan taxa. Additional unusual traits include the leaves, which are broad and sub-petiolate, and the dense coating of brownish hairs which cover all parts of the plant, giving it a “wooly” appearance. Unfortunately, as our expedition was purely a photographic one we did not collect herbarium specimens, and a formal description of this species will have to wait for a future survey equipped with collecting permits.

Nepenthes sp. New GuineaNepenthes sp. New Guinea

This discovery is further remarkable considering the relative paucity of Nepenthes in New Guinea. Despite the island’s vast size, the presently recognized diversity of the genus on the New Guinea mainland is quite small (only 11 species). Unlike other islands of the Indonesian archipelago such as Borneo (39 species) and Sumatra (37 species), where pitcher plants occur in abundance on most mountains exceeding 2000 m, Nepenthes are patchily distributed in New Guinea and are seemingly absent from large regions of highland areas. In 2004 and 2006 I climbed two separate mountains each exceeding 3000 m in elevation and, whilst the habitats were very rich in a variety of typically associated plants, I did not observe a single Nepenthes.

Notwithstanding the large number of new Nepenthes which have been distinguished in recent years, the addition of this interesting species shows that we still have a long way to go towards our complete understanding of the genus, with perhaps other great discoveries to be made in the mountains of Papua.

References:

Jebb, M. & M. Cheek (1997) A Skeletal Revision of Nepenthes (Nepenthaceae). Blumea 42: 1-106.

Jebb, M.H.P. 1991. An account of Nepenthes in New Guinea. Science in New Guinea 17(1): 7–54.

New Pitcher Plant Discoveries

2 February 2012

The incredible diversity of Tropical Pitcher Plants (Nepenthes) becomes more evident each year as new species continue to be discovered across Southeast Asia. As recently as 1997, a total of only 82 Nepenthes were recognized, but in the past 15 years new findings and some taxonomic splits bring the world total to nearly 140 species today. Many of these new discoveries not only showcase the fascinating ecological adaptations and trap designs that make these carnivorous plants so successful, but they also help to shed light on their possible evolutionary relationships and biogeographical pathways.

I was fortunate to be able to contribute towards several papers in a recent publication “The New Nepenthes – vol. 1″ (Dec 2011) which compiles work from multiple authors and describes eight new Nepenthes species that have been found in recent years. Two of these, N. undulatifolia (below left) and N. nigra are from Sulawesi, an island with a relatively impoverished Nepenthes flora of only 11 species. The highly unusual N. undulatifolia was an exciting find for botanists because it could not be clearly grouped with any other closely related species.

The remote Hose Mountains in central Sarawak, an area where I had discovered two other endemic Nepenthes in 2001, yielded another new species, N. appendiculata (below right), during a study in 2011. This species was named for the remarkable swollen appendage protruding from the tip of the pitcher lid, a feature unlike any other species in the genus. Presumably an aid in the attraction of insect prey, this appendage is brightly colored and riddled with large nectar glands. Further field work may determine what types of insects this plant specializes in feeding on.

Nepenthes undulatifoliaNepenthes appendiculata

References:

Jebb, M. & M. Cheek (1997) A Skeletal Revision of Nepenthes (Nepenthaceae). Blumea 42: 1-106.

Lee, C.C., G. Bourke, W. Taylor, Y.S. Teck, K. Rembold (2011) Nepenthes appendiculata, a new Pitcher Plant from Sarawak. In The New Nepenthes, Redfern Natural History Publications Ltd. 1: 24-35.

Lee, C.C., A. Wistuba, J. Nerz, U. Zimmermann, A.P. Paserang, R. Pitopang (2011) Nepenthes undulatifolia, a new Pitcher Plant from South East Sulawesi. In The New Nepenthes, Redfern Natural History Publications Ltd. 1: 492-505.

Nerz, J., A. Wistuba, C.C. Lee, G. Bourke, U. Zimmermann, S. McPherson (2011) Nepenthes nigra, a new Pitcher Plant from Central Sulawesi. In The New Nepenthes, Redfern Natural History Publications Ltd. 1: 468-491.

Nepenthes rajah and the Summit Rat

15 June 2011

Nepenthes rajah and Rattus baluensis

In late 2010 I was fortunate to be able to join a team of researchers investigating animal interactions with the giant pitcher plant Nepenthes rajah. Endemic to the cool and mist-shrouded slopes of Mount Kinabalu and Mount Tambuyuon in northern Borneo, this is not only one of the world’s largest Nepenthes but also the source of the original stories of “rat-eating” carnivorous plants. There exist a number of confirmed incidents of this plant consuming small mammals which are unfortunate enough to fall within the voluminous pitchers. Recent research however, has shed light on a far more interesting and complex animal/plant relationship, and prior to our 2010 work it had been already shown that the Mountain Treeshrew (Tupaia montana) visits the pitchers of N. rajah (as well as several other Bornean Nepenthes) to feed on the sweet nectar exuding from beneath the pitcher lid. The plant benefits from these visits by frequently collecting the treeshrew’s scat which fall inside the pitcher and are a valuable source of nutrients.

During the field work it was observed that some of the animal droppings found on and in the pitchers appeared different than those left behind by the Mountain Treeshrew. However, despite many days of watching the plants during daylight hours, treeshrews were the only mammals seen to visit the plants. It wasn’t until camera equipment was left in place to monitor the plants during the night that we ascertained the presence of another animal, the Summit Rat (Rattus baluensis) at the pitchers. This is the first instance confirming a rodent/Nepenthes relationship, and it is presumed that it matches the treeshrew/Nepenthes mutualism albeit nocturnally. The photo here, the first ever to illustrate this interaction, shows an image I obtained at night by use of an infrared camera trap positioned adjacent to the pitcher and illuminated by multiple strobes.

Unlike the related Nepenthes lowii, another Bornean pitcher plant which has lost its means to trap insects and depends entirely on the treeshrew droppings for its nutrients, N. rajah retains its carnivorous apparati, a slippery peristome and smooth pitcher walls, and still consumes prey. It is quite likely that the records of rats and treeshrews having drowned in N. rajah pitchers were not instances of these mammals seeking out a source of water (as has been assumed in the past), but rather the result of unfortunate animals falling into their “toilet”.

References:

Chin, L.J., J.A. Moran, C. Clarke (2010) Trap geometry in three giant montane pitcher plant species from Borneo is a function of tree shrew body size. New Phytologist 186: 461–470.

Clarke, C.M., U. Bauer, C.C. Lee, A.A. Tuen, K. Rembold (2009) Tree shrew lavatories: a novel nitrogen sequestration strategy in a tropical pitcher plant. Biology Letters 5: 632–635.

Greenwood, M., C. Clarke, C.C. Lee, A. Gunsalam & R.H. Clarke (2011) A Unique Resource Mutualism between the Giant Bornean Pitcher Plant, Nepenthes rajah, and Members of a Small Mammal Community. PLoS ONE 6:6.


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