Another Nice Trip to Sumatra
Keywords: travelogue:Nepenthes¾ travelogue:Sumatra
Sumatra is definitely the trendy location for Nepenthes explorers
at the moment. In the last two years, seven species have been described
from the island and the list of Sumatran Nepenthes now rivals that
of Borneo in size. Over the last eight years, I have spent a considerable
amount of time exploring Borneo and studying its Nepenthes. During
that time, numerous reports of new species from Sumatra surfaced and the
urge for me to visit the island and see some of them grew and grew. The
CPN article by Hopkins et al. (1990) added further fuel to the
fire, as it became apparent to me that it was possible to see most of
the Sumatran species in a short space of time and with relatively little
effort compared to the exertions required to find many of the Bornean
Nepenthes. Moreover, it seemed that a number of Sumatran Nepenthes
were not very well understood taxonomically and the longer a situation
such as that goes on, the more difficult it becomes to sort out.
Finally, in September 1995, I got my chance to visit Sumatra. A letter
earlier in the year from a friend, who thought he had found a new species
from Sumatra, helped bring my plans to fruition. We decided the best way
of finding out the identity of his plant would be to go to Sumatra and
find it again, so that we could compare it with the other species in the
region and see if it was new. This provided the perfect excuse to try
to see as many other Nepenthes as possible while we were there.
This article provides an overview of the species we saw and is largely
a reply to the article by Hopkins et al. (1990). Where possible,
I have included discussion of the newly described Sumatran species, though
we did not manage to find all of these. The map of Sumatra provided by
Hopkins et al. (1990) includes all of the important destinations
we visited and can be used in conjunction with this article.
Our trip started at Medan, the capital of North Sumatra. I had been told
by many people that Medan was a place to avoid, but did not find it to
be that bad (especially when compared to Sibolga¾ see below!). We
drove from there to Berastagi, armed with the information that there were
numerous lowland Nepenthes by the road on the way. This may well
be the case, but we had almost reached Berastagi before we realised we
had left Medan! Any plants that might grow along this stretch of road
would have to wait for our return. From Berastagi, we drove around the
edge of Lake Toba to Prapat. We saw a lot of N. tobaica on the
way, but nothing else. Most of the pitchers were greenish-yellow, but
a couple were a nice coffee-brown colour.
The next day, we climbed Gunung Pangulubao. Since Kurata (1972) described
N. rhombicaulis from this mountain it has become something of a
beacon for Nepenthes enthusiasts who visit Sumatra. Recently, N.
ovata, N. mikei and N. xiphioides have been described from
G. Pangulubao (Nerz & Wistuba, 1994; Salmon & Maulder, 1995),
making it one of the richest locations for Nepenthes species in
Sumatra. The climb to and from the summit can be done in a day and we
saw N. rhombicaulis, N. ovata (Figure 1) and N. spectabilis
there. On the way down we saw N. tobaica, N. ampullaria and a species
of Paphiopedilum, but it was not in flower. Despite an extensive
search around the summit area, we did not see N. mikei or N.
xiphioides. However, the summit ridge of G. Pangulubao is quite long
and can be reached from more than one direction, so we assumed that we
were simply not in the right place at the right time. From the photos
which accompanied the description of N. mikei (Salmon and Maulder,
1995), there seems to be no doubt that it is quite distinct from any other
species, though N. xiphioides is now considered a synonym of N.
gymnamphora (Schlauer, 1996).
If N. rhombicaulis was the only known species of Nepenthes,
it would probably be considered fairly spectacular. Unfortunately, it
is not and almost all other Nepenthes are more interesting than
it is! The upper pitchers are rarely produced, though we did manage to
find one small one (Schmid-Hollinger (1994) managed to find more) and
the lower pitchers are often embedded in moss and detritus. It grows just
below the summit, often below the point at which mossy forests occur.
In this sense, it reminded me of N. hirsuta of Borneo, which also
grows in the litter layer of montane forests. Hopkins et al. (1990)
were not entirely sure about the identity of some of the pitchers they
found on G. Pangulubao. The two photographs at the top of page twenty-one
of their article illustrate N. rhombicaulis, though I am not 100%
certain about the one with the large brown peristome¾ that looks
a bit like N. ovata¾ but a lot more information is required
before any conclusions can be drawn. Perhaps those authors now know the
Fortunately, the extreme development of the peristome of N. ovata
pitchers makes up for the drabness of N. rhombicaulis. N.
ovata is largely epiphytic, but also grows in mossy banks beside the
trail. The lower pitchers are superb, with expanded dark red peristomes
and light green cups. The upper pitchers are less spectacular, but are
a very elegant shape. N. spectabilis was not quite as common as
we had expected and we got the impression that collectors had taken a
bit of a toll on the population, partly because very few immature plants
were visible. However, we did not get the chance to examine this species
on Gunung Sinabung, so we cannot really draw any serious conclusions about
the densities at which it grows. We climbed down G. Pangulubao using a
different path to the one we climbed up. We thought this would increase
our chances of seeing N. mikei, but the path did not follow the
direction we expected it to and all we saw was more N. tobaica.
Our guide then took us to a site where he said another Nepenthes
grew. We walked across rice paddies for about twenty minutes, until we
came to a small patch of swampy vegetation. The plants turned out to be
N. ampullaria, but the leaves were quite different in shape to
those of the Bornean N. ampullaria. They were larger, more acute
at the apex and the lateral venation was a lot more pronounced. We could
not figure out what they were until one of the local children picked one
of the pitchers out from the depths of the swamp!
The next day, we drove down to Sibolga to look for N. sumatrana
(Figure 2) and the other lowland species known from that area. Since Danser
(1928) united them, N. sumatrana and N. treubiana have both
been known by the latter name and the only other known location was in
Irian Jaya. Jebb (1991) examined the herbarium specimens of the Sumatran
and Irianese populations and felt that there were some substantial differences,
but stopped short of reclassifying either of them. Nerz & Wistuba
(1994) concluded that the differences between the plants at the two sites
were sufficient to reclassify them and the Irianese populations are now
known as N. treubiana, whereas the Sumatran ones have been returned
to their original name of N. sumatrana.
We were also able to confirm the observation of Hopkins et al.
(1990) that the distribution of N. tobaica does extend some distance
west of the lake towards Sibolga¾ we found plants as low as 700 m
above sea level. Growing with N. sumatrana we saw more N. ampullaria,
N. gracilis and a few pathetic specimens of N. reinwardtiana.
We found a number of plants of the black form of N. gracilis (both
here and close to Sibolga) but, contrary to the opinions of Hopkins et
al. (1990), I think they are pretty ordinary compared to the black
ones from north-western Borneo!
A little further down the road we saw a large stand of what is usually
referred to as the Sumatran N. alata (Figure 3). Some people feel
that the Sumatran populations of N. alata differ sufficiently from
those of the Philippines to be considered a separate species. Others do
not and it will be interesting to see how the current monographers such
as Martin Cheek and Matthew Jebb treat these populations. If the Sumatran
populations are returned to species status, they will assume their old
epithet: N. eustachya.
Later that day, we arrived in Sibolga and set about looking for a hotel.
Thirty minutes later, having decided that it was the grubbiest little
town we had ever had the misfortune to stumble across, we decided to drive
on to Bukittinggi, 350 km away.
We got to Bukittinggi at midnight, exhausted but glad to be somewhere
a little more civilised. This pleasant town is best known for the three
large mountains which surround it: G. Merapi, G. Singgalang and G. Sago.
Unfortunately, we only had time to climb one of these on this trip and
we chose G. Singgalang.
The climb up Gunung Singgalang starts from a radio repeater station at
about 1400 metres above sea level. From there, it was a relatively easy
(though long) walk up a clear path to the summit. A short distance along
the trail, we found a number of plants of N. gymnamphora growing
in a bamboo thicket (Figure 4). The moss forest further up the trail was
very pretty, but the trail was strewn with rubbish and there were few
Nepenthes to see. We found one very impressive plant of N. bongso
(Figure 5) on the way up, but apart from that, we had to wait until we
reached the crater lake near the summit to see any more. N. bongso
has had a very confused history and even though much of this confusion
has now been untangled (see below), it is still a difficult plant to distinguish
The crater lake at the top of G. Singgalang is quite picturesque, but
is also surrounded by piles of rubbish. The actual summit is a little
further along the trail, at the far end of the lake. We spent an hour
walking up to this, as I was expecting to see the best stand of Nepenthes
on the mountain there, but was surprised to find that none grew there
at all: they are all found around the shores of the lake and all of them
are N. singalana. This species is quite similar to N. bongso.
The upper pitchers of N. singalana are very plain, but the lower
ones are more interesting and are often a nice black colour. N. pectinata
was also known from this mountain (as well as several others in the region),
but Schlauer and Nerz (1994) showed that the specimens upon which the
description of N. pectinata was based consisted of the lower pitchers
of N. gymnamphora and the upper pitchers of N. singalana.
N. pectinata is no longer considered to be a valid species. Although
the climb up G. Singgalang was a good way to learn about the differences
between N. bongso and N. singalana, it is not a mountain
I would recommend to someone who is pressed for time and who wants to
see as many Nepenthes as possible!
Our next destination was an area west of Bukittinggi, called the Harau
Canyon. We were not sure what we would find here, but thought it was worth
taking a look. Nepenthes tenuis, a species recently described by
Nerz & Wistuba (1994) was apparently collected on a sandstone ridge
above the river Tjampo. Given that the Harau Canyon contains a lot of
steep sandstone ridges, it seemed like a good place to look, but we did
not have the time to get serious about it. Nearby we found some nice stands
of Nepenthes, in particular N. alata. I wanted to find two
plants in particular: N. adnata and N. rafflesiana var.
longicirrhosa. The former was originally described invalidly by
Tamin & Hotta (1986), with the formal description coming from Schlauer
and Nerz (1994). N. rafflesiana var. longicirrhosa was also
described invalidly by Tamin & Hotta (1986), but has not been mentioned
Upon finding N. rafflesiana var. longicirrhosa, I was immediately
certain that it was not a variety of N. rafflesiana at all and
I do not know what Tamin and Hotta (1986) were thinking of when they classified
it as such. After half an hour of head scratching, the penny dropped¾
this plant was the recently described N. longifolia (see Nerz and
Wistuba (1994)). N. longifolia is so closely related to N. sumatrana
that I sometimes find it difficult to see how these two can be distinguished
from each other at all (Figure 6). The pitchers of the two are different
in colour and there are some very minor morphological differences, but
in all other respects, including ecology, they are very similar indeed.
Growing near N. longifolia and N. alata were N. ampullaria,
N. gracilis and N. albomarginata. The N. albomarginata
from this part of Sumatra are large and robust compared to those from
Borneo and seem to be bigger than those from Peninsular Malaysia as well.
Shivas (1985) commented on these differences and it does seem that this
species exhibits greater geographical variations than most.
We saw some quite large and unusual plants of N. gracilis and
given that we had spent the whole day looking for N. adnata without
success decided that maybe that is what the latter species looks like.
Just as we were about to give up altogether, we found the real thing (Figure
7). N. adnata must be one of the smallest of all Nepenthes,
but it is also one of the prettiest. The basal rosettes rarely exceed
15 cm in diameter and the pitchers rarely exceed 8 cm in height, but the
whole plant is very beautiful and grows among thick mosses. It is an outstanding
addition to the genus and it is nice to think that even after all this
time and exploration, there are still some great botanical discoveries
to be made in the forests of Southeast Asia. Satisfied, we returned to
Bukittinggi to prepare for the next stage of our trip.
The plant we both wanted to see most was N. inermis. This species
is known from a few mountains in West Sumatra and we wanted to visit Gunung
Gadut, a locality which has only recently come to light. This mountain
is also home to N. carunculata var. robusta¾ an extreme
variety of this species described by Nerz and Wistuba (1994). Our U.S.
Air Force map (albeit an old one) showed various paths and trails going
up to this mountain from the town of Solok, which is near the better-known
Gunung Talang. We looked for these trails for almost half a day, but could
not find them. Perhaps they have been reclaimed by the jungle since the
printing of the map? Or, more likely, we simply looked in the wrong places!
We then decided to drive down to Padang and see if there was a way up
from the other side. Eventually we found a trail up from this side, but
we did not have enough time to complete the walk. Having failed at the
first attempt, we had to decide whether or not to try again the next day,
or whether to climb Gunung Talang instead. We chose G. Talang, as we wanted
to be absolutely sure of seeing N. inermis.
Our ascent of Gunung Talang was a rather unusual one and I suspect that
not many westerners have climbed it using the paths we did! We hired a
few local guides for the day and they took us along their hunting trails
in a slow, winding ascent of the mountain. We did not quite reach the
summit, which was a minor disappointment, but to climb such a spectacular
mountain along virtually unused trails was great. We saw a lot of Paphiopedilum
orchids, but once again, they were not in flower. The mossy forest on
this mountain was particularly impressive. N. gymnamphora grew
in dark places on the lower slopes of the mountain. Some of them had more
substantial peristomes than others we had seen and I wondered if this
was the plant named N. rosulata by Tamin and Hotta (1986). If so,
any differences between it and N. gymnamphora are definitely not
sufficient for it to be distinguished as a new species.
Further up, we found our goal. A large tree had fallen near the path
and there was a plant of N. inermis growing on it. Only a Nepenthes
fanatic could find this plant as amazing as we did¾ it has no
peristome, little colour and is very small (Figure 8). Nonetheless, it
is up there with the best species in my opinion. A few articles have discussed
the possible prey-trapping mechanisms of this plant (see Hopkins et
al. (1990) and Salmon (1993)). Salmon (1993) suggested that the pitcher
secretes compounds which serve to intoxicate insects which land on the
lid. These are then rendered paralysed and cannot move even if you touch
them. He also suggested that the extreme viscosity of the pitcher fluid
helped prevent the contents being washed away by rain.
In the wild, I noticed that the entire inner surfaces of N. inermis
pitchers have a thin covering of pitcher fluid, which is so viscous
that it feels sticky in the same way as the mucilage on the tentacles
of Drosera species. We saw several insects trapped on the upper
parts of the pitchers (on the inside) by this mucilage. They could not
break free from it and were in the process of sliding into the pitcher.
Because the fluid also acts as a lubricant, the captured insects slide
down into the narrow base of the pitchers very easily. There, the walls
of the pitcher are so tightly pressed together that there is no chance
of rainwater washing the contents out. Presumably, this is where the prey
are digested. It would be very interesting to see whether the secretions
on the lid do in fact contain substances which are intoxicating to insects;
whatever the case, the pitchers have a very sweet and aromatic smell.
Although controlled experiments would be required to prove exactly how
N. inermis pitchers work, it seems to me that they function partly
as pitfall traps and partly as flypapers. Regardless of the final outcomes
of such experiments, there is no doubt that N. inermis is one of
the most unusual and remarkable of all Nepenthes.
The next plant we saw on Gunung Talang was N. talangensis. For
a long time, people thought that this was N. bongso (see Hopkins
et al. (1990), p. 23). This may have been due in part to the considerable
confusion among horticulturists regarding the differences between N.
bongso, N. carunculata, N. pectinata and N. singalana.
Some of this confusion was resolved by Schlauer & Nerz (1994) but
the differences between N. bongso and N. carunculata are
still difficult to interpret (see below). N. talangensis was named
by Nerz and Wistuba (1994) and it is not known from anywhere else. It
is very common in the mossy forest near the top of G. Talang, but also
occurs lower down. We saw some plants at 1800 metres. At first, we thought
these looked like natural hybrids of N. gymnamphora and N. inermis.
They certainly do have an intermediate appearance, but once we saw
more of them higher up the mountain, it became clear that they were not
hybrids. The mossy forest on the summit ridges of G. Talang is very easy
to walk through, as there are many tracks formed by Tapir, a large black
and white coloured mammal, about the size of a large pig, which is found
in Sumatra and Peninsular Malaysia.
On the way down the mountain, we saw a couple of very large Nepenthes
plants, the first of which we decided (without much conviction) was a
true N. bongso. Having not seen a clear-cut example of N. carunculata
on the trip, I cannot honestly say that I understand the differences between
this species and N. bongso. N. carunculata usually but not
always has an appendage on the underside of the lid, towards the apex.
However, because this is not always present and the other differences
with N. bongso are slight, I could not be 100% sure of our identification.
Back to North Sumatra
Our final goal was to look for another plant which was partly (and invalidly)
described by Tamin and Hotta (1986)¾ N. spinosa. The description
of this species is yet to be sorted out, but we had time to have a quick
look for it near Solok. This attempt turned out to be unsuccessful as
well, but we did see a lot of N. reinwardtiana. As we had to get
back to Medan to meet our flights back home, we started the long drive
north, taking a different route so as to avoid visiting Sibolga again!
We drove around the base of Gunung Talakmau, in case we wanted to climb
it at some later date and there we found a few plants of N. mirabilis
growing by the road. From there we went back to Lake Toba and on to
Medan. In ten days, we saw eighteen species of Nepenthes, which
was not bad going at all. While it is clear that there is still some confusion
about certain species from Sumatra, the situation is a lot better than
it was a couple of years ago, thanks largely to the sensible approaches
taken by Nerz, Wistuba and Schlauer in describing new species.
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Southeast Asia, Carnivorous Plant Newsletter, 19: 19-28.
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in New Guinea, 17 (1): 7-54.
Kurata, S. (1972) Nepenthes from Borneo, Singapore and Sumatra,
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from North and West Sumatra, Carnivorous Plant Newsletter, 23:
Salmon, B. (1993) Some Observations on the Trapping Mechanisms of Nepenthes
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Front Cover : N. adnata (a lower pitcher and part of the rosette). Photo by Charles Clarke.
Rear Cover: A rosette & lower pitcher of N. alata (considered by some to be N. eustachya). Photo by Charles Clarke