Nepenthes aristolochioides
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| Nepenthes aristolochioides | ||||||||||||||
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 Upper pitcher of N. aristolochioides
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| Nepenthes aristolochioides Jebb & Cheek (1997) |
Nepenthes aristolochioides (pronounced /nəˈpɛnθiːz ˈærɪstəʊləʊkiˌːɔɪdiːz/) is a tropical pitcher plant endemic to Sumatra, where it grows at elevations of between 2000 and 2500 m above sea level. It has an extremely unusual pitcher morphology, having an almost vertical opening to its traps. The specific epithet aristolochioides is formed from the genus name Aristolochia and the Latin ending -oides, meaning "resembling". It refers to the similarity that the pitchers of this species bear to the specialised flowers of Aristolochia.[1]
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[edit] Botanical history
N. aristolochioides was first collected by Willem Meijer on August 5, 1956. The holotype, Meijer 6542, was collected on that date from Mount Tujuh in Jambi at an elevation of 2000 m. It is deposited at the National Herbarium of the Netherlands in Leiden, but is in relatively poor condition.[2] An isotype is held at the Bogor Botanical Gardens (formerly the Herbarium of the Buitenzorg Botanic Gardens) in Java.[3]
Although labelled as "new species?",[2] the specimen was largely ignored for over 30 years. In 1988, botanist Joachim Nerz became aware of it upon visiting the herbarium of Leiden University. In the summer of 1996, Nerz met with Jan Schlauer and Willem Meijer in the Frankfurt Palmengarten, where Meijer showed him a photograph of the mysterious species. Together with Katrin Hinderhofer, Nerz organised a field trip to Sumatra in June 1996 which was successful in rediscovering N. aristolochioides in the wild.[2]
N. aristolochioides was finally described in 1997 by Matthew Jebb and Martin Cheek. The description was published in their monograph "A Skeletal Revision of Nepenthes (Nepenthaceae)" in the botanical journal Blumea.[1] Joachim Nerz wrote a detailed treatment of the species which was published in the Carnivorous Plant Newsletter the following year.[2]
[edit] Description
N. aristolochioides is a climbing plant. The stem grows to 8 m in length and 5 mm in diameter.[2] Internodes are cylindrical to obtusely angular in cross section and up to 15 cm long.[3]
Leaves are coriaceous and sessile. The lamina is spathulate-lanceolate in form and up to 15 cm long and 3 cm wide. It has an acute apex and is gradually attenuate towards the base. Two to five[2] longitudinal veins are present on either side of the midrib. Pinnate veins are indistinct. Tendrils reach 15 cm in length.[3]
Rosette and lower pitchers are only produced on small rosettes before the plant begins to climb or on offshoots from the climbing stem. They are infundibular in the lower two-thirds and globose above. They reach 7 cm in height and 3 cm in width. The pitcher mouth is round and oblique to almost vertical. A pair of fringed wings (≤4 mm long) runs down the front of the pitcher. The peristome is broad, incurved, and up to 5 mm wide. Its inner margin is lined with small teeth that are curled at their apex. The glandular region covers almost the entire inner surface of the pitcher. Digestive glands are overarched, 0.2 to 0.3 mm in diameter, and occur at a density of 200 to 500 per square centimetre.[2] The pitcher lid or operculum is orbicular-cordate, up to 1.5 cm wide,[2] and bears no appendages. It is usually reflexed away from the mouth at an angle of around 90 degrees. A branched or unbranched spur (≤7 mm long) is inserted at the base of the lid.[3][2]
Upper pitchers are infundibular in the lower half and utriculate above. They are larger than terrestrial pitchers, reaching 15 cm in height and 8 cm in width, and bear ribs in place of wings. The pitcher mouth is positioned almost vertically. The peristome (≤6 mm wide)[2] is expanded and incurved, bearing indistinct teeth. The pitcher lid is ovate and often held horizontally. The glandular region covers the lower two-thirds of the pitcher cup's inner surface. Digestive glands are slightly overarched, 0.2 to 0.4 mm in diameter, and occur at a density of 200 to 250 per square centimetre.[2] In most other respects, upper pitchers are similar to their terrestrial counterparts.[3]
N. aristolochioides has a racemose inflorescence. Both the peduncle and rachis may be up to 15 cm long, although the latter is usually shorter in female plants. Pedicels are simple-bracteolate, one-flowered, and up to 12 mm long.[2] Sepals are ovate and up to 4 mm long.[3] Fruits are up to 20 mm long and 4 mm wide, and bear lanceolate valves. Seeds are filiform.[2]
Most parts of the plant are glabrous. The axils, midribs and parts of the pitchers may bear a sparse indumentum of short, simple white hairs.[3]
The stem and lamina are light green. Pitchers are white to reddish with numerous red-brown speckles. The peristome is usually dark red. The undersurface of the lid is red throughout, while the upper surface is speckled like the rest of the pitcher. Herbarium specimens are brown to dark brown, the preserved pitchers having dark spots.[2]
Little variation has been observed within natural populations of N. aristolochioides. As such, no forms or varieties have been described.[3]
[edit] Ecology
N. aristolochioides inhabits Sphagnum-dominated mossy forest near the tops of steep ridges. It usually grows terrestrially, but may also occur as an epiphyte in pockets of moss on tree trunks. N. aristolochioides has an altitudinal distribution of 2000 to 2500 m above sea level. It is only known from Mount Tujuh in Jambi, although specimens collected by Herbert Christopher Robinson and Cecil Boden Kloss labelled as being collected from "Mt. Kerinci" suggest that it may be more widespread in the region. Mount Kerinci is Sumatra's highest peak and neighbours Mount Tujuh.[4] Since most of the mountain remains unexplored, there is a good chance that N. aristolochioides occurs there as well. The full range of N. aristolochioides on Mount Tujuh is also unknown, since only three of the mountain's seven peaks have been climbed.[3]
The species occurs sympatrically with N. gymnamphora and N. singalana. The former occurs in montane forest and swamps dominated by Pandanus species that line the shoreline of a crater lake. The altitudinal distribution of N. gymnamphora on Mount Tujuh (1800 to 2100 m) overlaps that of N. aristolochioides, but no natural hybrids have been observed.[2]
A small form of N. singalana occurs in the same habitat as N. aristolochioides, but appears to occupy a different ecological niche; it is generally confined to the forest floor while N. aristolochioides often climbs into the canopy.[2] A number of plants representing the natural hybrid N. aristolochioides × N. singalana have been recorded.[3]
N. aristolochioides is listed as Critically Endangered on the 2006 IUCN Red List of Threatened Species, as its known distribution is restricted to a single mountain.[5] Despite the fact that all known populations of the species lie within Kerinci Seblat National Park, it is severely threatened by over-collection, because its unique pitcher morphology makes it particularly sought-after.[3]
[edit] Carnivory
Two different trapping mechanisms have been proposed for the lower and upper pitchers of N. aristolochioides.
The lower pitchers of this species frequently develop embedded in Sphagnum moss, with only the top of the traps visible. Joachim Nerz suggested that they act as simple pitfall traps specialised for trapping ground-dwelling insects. The insects crawl into the pitcher through the small mouth and fall to the bottom of the pitcher cup. Unable to climb out, they drown in the digestive fluid.[2]
Along with N. klossii, N. aristolochioides is the only species in the genus to employ domed pitchers with white patches that allow sunlight to illuminate the interior. When viewed from the front, the peristome and lid appear dark, in contrast to the inner surface of the pitcher, which is brightly lit by light passing through the top of the pitcher dome. It has been suggested that in upper pitchers this adaptation serves to attract flying insects in a similar manner to the North American pitcher plants Darlingtonia californica, Sarracenia minor, and Sarracenia psittacina.[2][3] A similar trapping mechanism has also been proposed for N. jacquelineae.[3] Prey are often disorientated inside the pitchers of N. arisotlochioides and are unable to find the exit, eventually falling into the pitcher fluid and drowning. Most of the prey caught by N. aristolochioides consists of small flies, which are attracted to bright light sources.[3][6]
No infaunal organisms have been recorded from the pitchers of N. aristolochioides. This is not due to a lack of potential inhabitants; pitchers of N. singalana, which grow alongside N. aristolochioides, support large populations of such organisms. It is thought that the structure of the traps may serve to disorientate emerging adults and so infaunal species avoid colonising them.[3]
[edit] Related species
The unusual pitcher morphology of N. aristolochioides makes it difficult to confuse it with any other species. The almost vertical orientation of the pitcher mouth is a particularly unique characteristic.[2]
Joachim Nerz noted that N. aristolochioides shows "close affinities" to N. talangensis. However, it may be easily distinguished from that species on the basis of the pitcher mouth, which is horizontal in N. talangensis. In addition, the pitcher mouth of N. talangensis is elongated into a short neck, whereas N. aristolochioides lacks a neck altogether, with the lid being inserted in front of the pitcher. Both the mouth and lid are considerably larger in N. talangensis. The two taxa also differ somewhat in growth habit; N. talangensis occurs only terrestrially and is a weak climber, whereas N. aristolochioides occasionally grows as an epiphyte and climbs high into the forest canopy.[2][7]
In 2001, Charles Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia using 70 morphological characteristics of each taxon. The following is part of the resultant cladogram, showing "Clade 1", which has 51% bootstrap support. Its most strongly supported subclade is the sister pair of N. inermis and N. dubia, having 95% support.[3]
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Although N. aristolochioides resembles N. klossii in some respects, the two species are geographically isolated from each other and are not thought to be closely related.[2] The unique adaptations of these taxa might represent an example of convergent evolution, whereby two organisms not closely related independently acquire similar characteristics while evolving in separate, but comparable, ecosystems.
[edit] Natural hybrids
Only one natural hybrid involving N. aristolochioides is known. N. aristolochioides × N. singalana has been found in dense mossy forest on two ridges on Mount Tujuh, only one of which is populated by N. aristolochioides. It is relatively rare, which suggests that the two species flower at different times of the year. This hybrid is smaller than either of its parent species; the pitchers rarely exceed 5 cm in height. The lower pitchers resemble those of N. talangensis, but differ in having more pronounced peristome teeth. Upper pitchers are infundibular in the lower parts, ovoid in the middle, and cylindrical in the upper parts. This hybrid can be distinguished from N. aristolochioides on the basis of its narrow, cylindrical peristome and oblique mouth, as opposed to almost vertical in the latter.[3]
[edit] References
- ^ a b Jebb, M.H.P. & M.R. Cheek 1997. A Skeletal Revision of Nepenthes (Nepenthaceae). Blumea 42(1): 1–106.
- ^ a b c d e f g h i j k l m n o p q r s t u Nerz, J. 1998. Rediscovery of an outstanding Nepenthes: N. aristolochioides (Nepenthaceae). Carnivorous Plant Newsletter 27(3): 101–114.
- ^ a b c d e f g h i j k l m n o p q Clarke, C.M. 2001. Nepenthes of Sumatra and Peninsular Malaysia. Natural History Publications (Borneo), Kota Kinabalu.
- ^ Jacobs, M. 1938. Contributions to the Botany of Mount Kerintji and Adjacent Area in West Central Sumatra—I. Annales Bogorienses 3: 45–79.
- ^ Clarke, C.M., R. Cantley, J. Nerz, H. Rischer & A. Witsuba 2000. Nepenthes aristolochioides. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Listed as Critically Endangered (CR D v2.3).
- ^ Rice, B. 2007. Carnivorous plants with hybrid trapping strategies. Carnivorous Plant Newsletter 36(1): 23–27.
- ^ Nerz, J. & A. Wistuba 1994. Five new taxa of Nepenthes (Nepenthaceae) from North and West Sumatra. Carnivorous Plant Newsletter 23(4): 101–114.
[edit] External links
Miscellaneous: Nepenthes taxonomy • Nepenthes infauna
