Nepenthes eustachya
Encyclopedia
Nepenthes eustachya is a tropical pitcher plant
endemic to Sumatra
, where it grows from sea level to an elevation of 1600 m. The specific epithet eustachya, formed from the Greek
words eu (true) and stachys (spike), refers to the racemose
structure of the inflorescence
.
on the Sumatran coast near the port town of Sibolga
. This specimen, Teijsmann 529, was designated as the lectotype
of N. eustachya by Matthew Jebb
and Martin Cheek
in their 1997 monograph. It is deposited at the herbarium of the Bogor Botanical Gardens
along with two isotype
s.
Nepenthes eustachya was described in 1858 by Friedrich Miquel
. In 1908, John Muirhead Macfarlane
retained N. eustachya as a distinct species in his revision of the genus, titled "Nepenthaceae
".
B. H. Danser
did not support this interpretation and instead treated N. eustachya in synonymy with N. alata
in his seminal monograph, "The Nepenthaceae of the Netherlands Indies
", published in 1928. He wrote:
Danser also identified Ridley 16097 from Peninsular Malaysia
as N. alata, extending the species's range even further and making its apparent absence from Borneo
difficult to explain. Ridley 16097 is now thought to represent N. benstonei
.
Plants belonging to N. eustachya were identified as N. alata by a number of subsequent authors, including Shigeo Kurata
in 1973, Mitsuru Hotta
and Rusjdi Tamin in 1986, Mike Hopkins, Ricky Maulder and Bruce Salmon in 1990, and T. Sota, M. Mogi and K. Kato in 1998.
In 1997, N. eustachya was once again elevated to species rank by Matthew Jebb
and Martin Cheek
, who noted a number of differences between the two taxa
. Charles Clarke
supported this interpretation in his 2001 monograph, Nepenthes of Sumatra and Peninsular Malaysia
.
The specific epithet eustachya has been misspelled several times in the literature, including once by Otto Stapf
in 1886 as N. eustachys and once by Jacob Gijsbert Boerlage in 1900 as N. eustachia.
s are cylindrical in cross section and up to 12 cm long.
Leaves are coriaceous and petiolate. The lamina is oblong-lanceolate in shape and can be up to 20 cm long and 5 cm wide. It has a rounded to emarginate apex, which may be sub-peltate. The petiole
is canaliculate, not decurrent, and generally lacks wings. It clasps the stem for around half of its circumference. Two to four longitudinal veins are present on either side of the midrib. Pinnate veins arise obliquely from the midrib. Tendril
s reach 15 cm in length.
Rosette and lower pitchers are ovoid in the lowermost quarter and cylindrical above, frequently widening just below the peristome. They are up to 20 cm high and 4 cm wide. On the inner surface, the glandular region covers the ovoid portion of the pitcher cup. The pitchers lack wings, bearing a pair of ribs instead. The pitcher mouth is round and has an oblique insertion. The flattened peristome
may be up to 5 mm wide. Its inner margin is lined with indistinct teeth. The lid is sub-orbicular and lacks appendages. The spur
is up to 4 mm long and generally bifid.
Upper pitchers resemble their lower counterparts in most regards. They usually attain a slightly greater size and are infundibular in the uppermost quarter.
Nepenthes eustachya has a racemose
inflorescence
. The peduncle
is up to 40 cm long, whereas the rachis
reaches 30 cm in length. Partial peduncles are one- or two-flowered and lack bract
eoles. Sepal
s are lanceolate in form and up to 4 mm long.
Immature parts of the plant may bear a sparse indumentum
of white, mostly caducous hairs. Mature parts are glabrous throughout.
The stem and lamina are green. Pitchers are white to light pink with many red speckles. The underside of the lid is often darker than the rest of the pitcher. The peristome is usually yellowish and may bear red stripes.
Nepenthes eustachya is endemic to the Indonesia
n provinces of North Sumatra
and West Sumatra
; its natural range stretches from Sibolga
to the Padang Highlands. It has an altitudinal distribution of 0 to 1600 m above sea level.
Nepenthes eustachya usually grows in open, sunny sites on cliff faces and steep slopes at the forest margin. It is restricted to sandstone
substrates and often grows on bare rock. Where the species does occur it is common and may form dense clumps, such as those growing beside the road from Sibolga to Tarutung
in North Sumatra.
Nepenthes eustachya grows in close proximity to a number of other lowland species, including N. albomarginata
, N. ampullaria
, N. gracilis
, N. longifolia
, and N. sumatrana
. It is known to hybridise with all of these species.
The conservation status
of N. eustachya is listed as Least Concern
on the 2006 IUCN Red List of Threatened Species
.
of reddish or whitish hairs. Jebb and Cheek also compared the structure of the pitcher base: that of N. eustachya is angular and woody, being gradually attenuate towards the tendril. The base of N. alata traps, however, has a similar texture to the rest of the pitcher and is abruptly attenuate towards the tendril.
Nepenthes alata exhibits great variability across its range and it is inevitable that some plants will deviate from the characters outlined by Jebb and Cheek. However, the overall combination of morphological differences appears to be stable and it is this that demarcates these species.
Nepenthes eustachya bears a superficial resemblance to N. mirabilis
. It can be distinguished from that species on the basis of its lower pitchers, which lack wings, its fimbriate leaf margins on short shoots, and coriaceous leaves, as opposed to chartaceous in the latter.
Charles Clarke
notes that the upper pitchers of N. eustachya, which have a pronounced globose base, may resemble those of N. clipeata
from Borneo
and N. klossii
from New Guinea
. Nevertheless, it would be difficult to confuse these species as they have little else in common and are geographically isolated from each other.
In 2001, Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia
using 70 morphological characteristics of each taxon. The following is a portion of the resultant cladogram
, showing "Clade 5". It comprises the sister pair of N. eustachya and N. mirabilis
with 72% support, as well as a weakly supported subclade (69%) that includes N. longifolia and the sister taxa N. rafflesiana
and N. sumatrana
with 58% bootstrap support.
Nepenthes albomarginata
and N. eustachya grow in mixed populations at a number of locations in the Padang Highlands and Tapanuli. Natural hybrids between them appear to be relatively common around the river Tjampo in West Sumatra
. A young plant of N. albomarginata × N. eustachya pictured in Nepenthes of Sumatra and Peninsular Malaysia
was observed by Charles Clarke in 1998 on Bukit Kambut in West Sumatra
. It grew in secondary vegetation amongst a population of N. eustachya at an elevation of around 900 m. This plant was subsequently destroyed, but Clarke and Troy Davis found a number of other plants on Bukit Tjampo. The hybrids were growing in a dense thicket of ferns (Dicranopteris linearis
and Dipteris sp.) at approximately 750 m.
Nepenthes albomarginata × N. eustachya often produces reddish leaves and pitchers. The characteristic white band of N. albomarginata is present just below the peristome. In common with N. eustachya, the indumentum is almost completely absent from the leaves, which are sub-petiolate and wider than those of N. albomarginata. No mature plants of this hybrid have been observed and, as such, the upper pitchers and inflorescence remain unknown.
Nepenthes eustachya × N. longifolia
has been recorded from a number of locations near Payakumbuh
and Sibolga
, where its parent species are sympatric. It is relatively rare because N. eustachya and N. longifolia occur in markedly different habitats; the former usually grows in exposed, sunny sites, while the latter is more common in dense, shady forest. This hybrid differs from N. eustachya in having fringed lamina margins bearing short reddish-brown hairs. The peristome often has a distinctive raised section at the front, a characteristic inherited from N. longifolia. It can be distinguished from N. longifolia on the basis of its shorter tendrils and the presence of longitudinal furrows on the surface of the lamina, similar to those of N. eustachya.
In addition, putative natural hybrids with N. ampullaria
, N. gracilis
, and N. sumatrana
have been observed.
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...
endemic to Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
, where it grows from sea level to an elevation of 1600 m. The specific epithet eustachya, formed from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
words eu (true) and stachys (spike), refers to the racemose
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
structure of 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...
.
Botanical history
Nepenthes eustachya was probably first collected in February 1856 by Johannes Elias TeijsmannJohannes Elias Teijsmann
Johannes Elias Teijsmann was a botanist and plant collector. He was born in Arnhem, Netherlands.Teijsmann travelled to Java in 1830 as Gardener of Governor General van den Bosch. He was appointed the Curator of the Buitenzorg Botanic Gardens the following year, a post he held until 1869...
on the Sumatran coast near the port town of Sibolga
Sibolga
Sibolga is a city and a port on the west coast of North Sumatra province, in Indonesia. It is located on the western side of North Sumatra, facing the Indian Ocean and is a transit harbour to Nias island. It was hard hit during the 2004 Indian Ocean Earthquake.- History :Poncan Ketek Island in...
. This specimen, Teijsmann 529, was designated as the lectotype
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
of N. eustachya by Matthew Jebb
Matthew Jebb
Dr. Matthew H. P. Jebb is an Irish taxonomist and botanist specialising in the ant plant genera Squamellaria, Myrmecodia, Hydnophytum, Myrmephytum and Anthorrhiza, as well as the carnivorous plant genus Nepenthes....
and Martin Cheek
Martin Cheek
Dr. Martin Roy Cheek is a taxonomist and botanist specialising in the carnivorous plant genus Nepenthes.-Research:Cheek has described several new Nepenthes species, mostly with Matthew Jebb, including: N. argentii, N. aristolochioides, N. danseri, N. diatas,...
in their 1997 monograph. It is deposited at the herbarium of the Bogor Botanical Gardens
Bogor Botanical Gardens
The Bogor Botanical Gardens are located 60 km south of the capital of Jakarta in Bogor, Indonesia. The botanical gardens are situated in the city center of Bogor and adjoin the Istana Bogor...
along with two isotype
Isotype
Isotype can refer to:* In crystallography, an "isotype" is a synonym for isomorph* In biology, per the International Code of Botanical Nomenclature, the "isotype" is a duplicate of the holotype....
s.
Nepenthes eustachya was described in 1858 by Friedrich Miquel
Friedrich Anton Wilhelm Miquel
Friedrich Anton Wilhelm Miquel was a Dutch botanist.He was head of the botanical gardens at Rotterdam , Amsterdam and Utrecht . He directed the Rijksherbarium at Leiden from 1862...
. In 1908, John Muirhead Macfarlane
John Muirhead Macfarlane
John Muirhead Macfarlane was a Scottish botanist. He was born and educated in Scotland, where he occupied several different academic positions at the University of Edinburgh before emigrating to the United States to assume a professorial chair at the University of Pennsylvania in 1893. He held...
retained N. eustachya as a distinct species in his revision of the genus, titled "Nepenthaceae
Nepenthaceae (1908 monograph)
"Nepenthaceae" is a monograph by John Muirhead Macfarlane on the tropical pitcher plants of the genus Nepenthes. It was published in 1908 in Adolf Engler's Das Pflanzenreich...
".
B. H. Danser
B. H. Danser
Benedictus Hubertus Danser , often abbreviated B. H. Danser, was a Dutch taxonomist and botanist...
did not support this interpretation and instead treated N. eustachya in synonymy with N. alata
Nepenthes alata
Nepenthes alata is a tropical pitcher plant endemic to the Philippines. It is found on all the major islands of the archipelago, with the possible exception of Palawan. It is one of the easiest and most popular Nepenthes species in cultivation....
in his seminal monograph, "The Nepenthaceae of the Netherlands Indies
The Nepenthaceae of the Netherlands Indies
"The Nepenthaceae of the Netherlands Indies" is a seminal monograph by B. H. Danser on the tropical pitcher plants of the Dutch East Indies, North Borneo, the Malay Peninsula, and eastern New Guinea...
", published in 1928. He wrote:
N. eustachya Miq., only recorded from Sumatra and still distinguished by Macfarlane, is united with N. alata in the above. In his monograph, Macfarlane places N. alata in the group with carinate lid, N. eustachya among the species without keel on the lid ; yet he distinguishes a N. alata var. ecristata, without keel. For the rest there is hardly any difference to be stated between these two species and especially the inflorescences are strikingly alike.
Danser also identified Ridley 16097 from Peninsular Malaysia
Peninsular Malaysia
Peninsular Malaysia , also known as West Malaysia , is the part of Malaysia which lies on the Malay Peninsula. Its area is . It shares a land border with Thailand in the north. To the south is the island of Singapore. Across the Strait of Malacca to the west lies the island of Sumatra...
as N. alata, extending the species's range even further and making its apparent absence from Borneo
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....
difficult to explain. Ridley 16097 is now thought to represent N. benstonei
Nepenthes benstonei
Nepenthes benstonei is a tropical pitcher plant endemic to Peninsular Malaysia, where it occurs at elevations of 450–600 m above sea level...
.
Plants belonging to N. eustachya were identified as N. alata by a number of subsequent authors, including Shigeo Kurata
Shigeo Kurata
is a Japanese botanist and Nepenthes taxonomist whose work in the 1960s and 1970s contributed much to the current popularity of these plants. Of particular note is his 1976 guide, Nepenthes of Mount Kinabalu....
in 1973, Mitsuru Hotta
Mitsuru Hotta
is a Japanese botanist best known for his research on Araceae.Hotta was born in Osaka, Japan in 1937. He graduated from the Agricultural Department of Osaka Prefecture University in 1960. The same year, he took part in the Tonga and Fiji Expedition organised by Kyoto University...
and Rusjdi Tamin in 1986, Mike Hopkins, Ricky Maulder and Bruce Salmon in 1990, and T. Sota, M. Mogi and K. Kato in 1998.
In 1997, N. eustachya was once again elevated to species rank by Matthew Jebb
Matthew Jebb
Dr. Matthew H. P. Jebb is an Irish taxonomist and botanist specialising in the ant plant genera Squamellaria, Myrmecodia, Hydnophytum, Myrmephytum and Anthorrhiza, as well as the carnivorous plant genus Nepenthes....
and Martin Cheek
Martin Cheek
Dr. Martin Roy Cheek is a taxonomist and botanist specialising in the carnivorous plant genus Nepenthes.-Research:Cheek has described several new Nepenthes species, mostly with Matthew Jebb, including: N. argentii, N. aristolochioides, N. danseri, N. diatas,...
, who noted a number of differences between the two taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
. Charles Clarke
Charles Clarke (botanist)
Dr. Charles M. Clarke is a botanist and taxonomist specialising in the carnivorous plant genus Nepenthes. Clarke has an honours degree in Botany from Monash University in Melbourne, and a Ph.D. in Ecosystem Management at the University of New England, in Armidale, New South Wales.Clarke first...
supported this interpretation in his 2001 monograph, Nepenthes of Sumatra and Peninsular Malaysia
Nepenthes of Sumatra and Peninsular Malaysia
Nepenthes of Sumatra and Peninsular Malaysia is a monograph by Charles Clarke on the tropical pitcher plants of Sumatra, Peninsular Malaysia, and their minor surrounding islands. It was published in 2001 by Natural History Publications...
.
The specific epithet eustachya has been misspelled several times in the literature, including once by Otto Stapf
Otto Stapf
Otto Stapf FRS was an Austrian born botanist and taxonomist.Stapf trained in Vienna, moving to Royal Botanic Gardens, Kew in 1890. He was keeper of the Herbarium from 1909 to 1920...
in 1886 as N. eustachys and once by Jacob Gijsbert Boerlage in 1900 as N. eustachia.
Description
Nepenthes eustachya is a climbing plant. The stem attains a length of up to 5 m and a diameter of 0.8 cm. InternodePlant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
s are cylindrical in cross section and up to 12 cm long.
Leaves are coriaceous and petiolate. The lamina is oblong-lanceolate in shape and can be up to 20 cm long and 5 cm wide. It has a rounded to emarginate apex, which may be sub-peltate. The petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
is canaliculate, not decurrent, and generally lacks wings. It clasps the stem for around half of its circumference. Two to four longitudinal veins are present on either side of the midrib. Pinnate veins arise obliquely from the midrib. Tendril
Tendril
In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support, attachment and cellular invasion by parasitic plants, generally by twining around suitable hosts. They do not have a lamina or blade, but they can photosynthesize...
s reach 15 cm in length.
Rosette and lower pitchers are ovoid in the lowermost quarter and cylindrical above, frequently widening just below the peristome. They are up to 20 cm high and 4 cm wide. On the inner surface, the glandular region covers the ovoid portion of the pitcher cup. The pitchers lack wings, bearing a pair of ribs instead. The pitcher mouth is round and has an oblique insertion. The flattened peristome
Peristome
The word peristome is derived from the Greek peri, meaning 'around' or 'about', and stoma, 'mouth'. It is a term used to describe various anatomical features that surround an opening to an organ or structure. The term is used in plants and invertebrate animals, such as in describing the shells of...
may be up to 5 mm wide. Its inner margin is lined with indistinct teeth. The lid is sub-orbicular and lacks appendages. The spur
Spur (biology)
A spur in botany is a spike, usually part of a flower.In certain plants, part of a sepal or petal develops into an elongated hollow spike extending behind the flower, containing nectar which is sucked by long-tongued animals . Plants with such structures include Delphinium, Aquilegia, Piperia, and...
is up to 4 mm long and generally bifid.
Upper pitchers resemble their lower counterparts in most regards. They usually attain a slightly greater size and are infundibular in the uppermost quarter.
Nepenthes eustachya has a racemose
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
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...
. The peduncle
Peduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...
is up to 40 cm long, whereas the rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
reaches 30 cm in length. Partial peduncles are one- or two-flowered and lack bract
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
eoles. Sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s are lanceolate in form and up to 4 mm long.
Immature parts of the plant may bear a sparse indumentum
Indumentum
The indumentum is a covering of fine hairs or bristles on a plant or insect.In plants, the indumentum types are:*pubescent*hirsute*pilose*villous*tomentose*stellate*scabrous*scurfy...
of white, mostly caducous hairs. Mature parts are glabrous throughout.
The stem and lamina are green. Pitchers are white to light pink with many red speckles. The underside of the lid is often darker than the rest of the pitcher. The peristome is usually yellowish and may bear red stripes.
Ecology
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n provinces of North Sumatra
North Sumatra
North Sumatra is a province of Indonesia on the Sumatra island. Its capital is Medan. It is the most populous Indonesian province outside of Java. It is slightly larger than Sri Lanka in area.- Geography and population :...
and West Sumatra
West Sumatra
West Sumatra is a province of Indonesia. It lies on the west coast of the island Sumatra. It borders the provinces of North Sumatra to the north, Riau and Jambi to the east, and Bengkulu to the southeast. It includes the Mentawai Islands off the coast...
; its natural range stretches from Sibolga
Sibolga
Sibolga is a city and a port on the west coast of North Sumatra province, in Indonesia. It is located on the western side of North Sumatra, facing the Indian Ocean and is a transit harbour to Nias island. It was hard hit during the 2004 Indian Ocean Earthquake.- History :Poncan Ketek Island in...
to the Padang Highlands. It has an altitudinal distribution of 0 to 1600 m above sea level.
Nepenthes eustachya usually grows in open, sunny sites on cliff faces and steep slopes at the forest margin. It is restricted to sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
substrates and often grows on bare rock. Where the species does occur it is common and may form dense clumps, such as those growing beside the road from Sibolga to Tarutung
Tarutung
Tarutung is a town in North Sumatra province of Indonesia and it is the seat of North Tapanuli Regency.Tarutung in Batak language means durian, because there was a lot of durian trees there....
in North Sumatra.
Nepenthes eustachya grows in close proximity to a number of other lowland species, including N. albomarginata
Nepenthes albomarginata
Nepenthes albomarginata , the White-Collared Pitcher-Plant, is a tropical pitcher plant native to Borneo, Peninsular Malaysia, and Sumatra...
, N. ampullaria
Nepenthes ampullaria
Nepenthes ampullaria , the Flask-Shaped Pitcher-Plant, is a very distinctive and widespread species of Nepenthes, present in Borneo, Sumatra, Thailand, Peninsular Malaysia, Singapore, the Maluku Islands, and New Guinea...
, N. gracilis
Nepenthes gracilis
Nepenthes gracilis , or the Slender Pitcher-Plant, is a very common lowland pitcher plant that is widespread in the Sunda region. It has been recorded from Borneo, Peninsular Malaysia, Singapore, central Sulawesi, Sumatra, and southernmost Thailand...
, N. longifolia
Nepenthes longifolia
Nepenthes longifolia is a tropical pitcher plant endemic to Sumatra, where it grows at elevations of between 300 and 1100 m above sea level. The specific epithet longifolia, formed from the Latin words longus and folius , refers to the exceptionally large leaves of this species.-Botanical...
, and N. sumatrana
Nepenthes sumatrana
Nepenthes sumatrana is a tropical pitcher plant endemic to the Indonesian island of Sumatra, after which it is named.-Discovery and taxonomy:...
. It is known to hybridise with all of these species.
The conservation status
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
of N. eustachya is listed as Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
on the 2006 IUCN Red List of Threatened Species
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
.
Related species
Nepenthes eustachya differs from N. alata in a number of morphological features. Jebb and Cheek outlined these differences when they restored the former as a valid species. Nepenthes eustachya has a lanceolate lamina with a rounded to sub-peltate apex, whereas that of N. alata is lanceolate-ovate with an acute or attenuate apex. The petiole also serves to distinguish these species: in N. eustachya it is scarcely or not winged at all, whereas in N. alata it is broadly winged. The pitchers of N. eustachya bear a simple or bifurcate spur, compared to the simple and acutely pointed appendage of N. alata. Mature parts of N. eustachya are glabrous, while N. alata bears an indumentumIndumentum
The indumentum is a covering of fine hairs or bristles on a plant or insect.In plants, the indumentum types are:*pubescent*hirsute*pilose*villous*tomentose*stellate*scabrous*scurfy...
of reddish or whitish hairs. Jebb and Cheek also compared the structure of the pitcher base: that of N. eustachya is angular and woody, being gradually attenuate towards the tendril. The base of N. alata traps, however, has a similar texture to the rest of the pitcher and is abruptly attenuate towards the tendril.
Nepenthes alata exhibits great variability across its range and it is inevitable that some plants will deviate from the characters outlined by Jebb and Cheek. However, the overall combination of morphological differences appears to be stable and it is this that demarcates these species.
Nepenthes eustachya bears a superficial resemblance to N. mirabilis
Nepenthes mirabilis
Nepenthes mirabilis , or the Common Swamp Pitcher-Plant, is a tropical carnivorous plant species of the pitfall trap variety. It has by far the widest distribution of any Nepenthes species and is known from the following countries and regions: Borneo, Sumatra, Thailand, Peninsular Malaysia,...
. It can be distinguished from that species on the basis of its lower pitchers, which lack wings, its fimbriate leaf margins on short shoots, and coriaceous leaves, as opposed to chartaceous in the latter.
Charles Clarke
Charles Clarke (botanist)
Dr. Charles M. Clarke is a botanist and taxonomist specialising in the carnivorous plant genus Nepenthes. Clarke has an honours degree in Botany from Monash University in Melbourne, and a Ph.D. in Ecosystem Management at the University of New England, in Armidale, New South Wales.Clarke first...
notes that the upper pitchers of N. eustachya, which have a pronounced globose base, may resemble those of N. clipeata
Nepenthes clipeata
Nepenthes clipeata , or the Shield-Leaved Pitcher-Plant, is a tropical pitcher plant known only from the near-vertical granite cliff faces of Mount Kelam in Kalimantan, Borneo...
from Borneo
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....
and N. klossii
Nepenthes klossii
Nepenthes klossii is a tropical pitcher plant endemic to New Guinea.-Botanical history:Nepenthes klossii was discovered in southwestern New Guinea during the Wollaston Expedition of 1912 to 1913...
from New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. Nevertheless, it would be difficult to confuse these species as they have little else in common and are geographically isolated from each other.
In 2001, Clarke performed a cladistic analysis of the Nepenthes species of Sumatra and Peninsular Malaysia
Peninsular Malaysia
Peninsular Malaysia , also known as West Malaysia , is the part of Malaysia which lies on the Malay Peninsula. Its area is . It shares a land border with Thailand in the north. To the south is the island of Singapore. Across the Strait of Malacca to the west lies the island of Sumatra...
using 70 morphological characteristics of each taxon. The following is a portion of the resultant cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
, showing "Clade 5". It comprises the sister pair of N. eustachya and N. mirabilis
Nepenthes mirabilis
Nepenthes mirabilis , or the Common Swamp Pitcher-Plant, is a tropical carnivorous plant species of the pitfall trap variety. It has by far the widest distribution of any Nepenthes species and is known from the following countries and regions: Borneo, Sumatra, Thailand, Peninsular Malaysia,...
with 72% support, as well as a weakly supported subclade (69%) that includes N. longifolia and the sister taxa N. rafflesiana
Nepenthes rafflesiana
Nepenthes rafflesiana , or Raffles' Pitcher-Plant, is a species of pitcher plant. It has a very wide distribution covering Borneo, Sumatra, Peninsular Malaysia, and Singapore. Nepenthes rafflesiana is extremely variable with numerous forms and varieties described. In Borneo alone, there are at...
and N. sumatrana
Nepenthes sumatrana
Nepenthes sumatrana is a tropical pitcher plant endemic to the Indonesian island of Sumatra, after which it is named.-Discovery and taxonomy:...
with 58% bootstrap support.
Natural hybrids
Nepenthes eustachya is known to hybridise with a number of other Nepenthes species with which it is sympatric.Nepenthes albomarginata
Nepenthes albomarginata
Nepenthes albomarginata , the White-Collared Pitcher-Plant, is a tropical pitcher plant native to Borneo, Peninsular Malaysia, and Sumatra...
and N. eustachya grow in mixed populations at a number of locations in the Padang Highlands and Tapanuli. Natural hybrids between them appear to be relatively common around the river Tjampo in West Sumatra
West Sumatra
West Sumatra is a province of Indonesia. It lies on the west coast of the island Sumatra. It borders the provinces of North Sumatra to the north, Riau and Jambi to the east, and Bengkulu to the southeast. It includes the Mentawai Islands off the coast...
. A young plant of N. albomarginata × N. eustachya pictured in Nepenthes of Sumatra and Peninsular Malaysia
Nepenthes of Sumatra and Peninsular Malaysia
Nepenthes of Sumatra and Peninsular Malaysia is a monograph by Charles Clarke on the tropical pitcher plants of Sumatra, Peninsular Malaysia, and their minor surrounding islands. It was published in 2001 by Natural History Publications...
was observed by Charles Clarke in 1998 on Bukit Kambut in West Sumatra
West Sumatra
West Sumatra is a province of Indonesia. It lies on the west coast of the island Sumatra. It borders the provinces of North Sumatra to the north, Riau and Jambi to the east, and Bengkulu to the southeast. It includes the Mentawai Islands off the coast...
. It grew in secondary vegetation amongst a population of N. eustachya at an elevation of around 900 m. This plant was subsequently destroyed, but Clarke and Troy Davis found a number of other plants on Bukit Tjampo. The hybrids were growing in a dense thicket of ferns (Dicranopteris linearis
Dicranopteris linearis
Dicranopteris linearis is a common species of fern known by many common names, including Old World forked fern and uluhe . It is one of the most widely distributed ferns of the wet Old World tropics and adjacent regions, including Polynesia and the Pacific...
and Dipteris sp.) at approximately 750 m.
Nepenthes albomarginata × N. eustachya often produces reddish leaves and pitchers. The characteristic white band of N. albomarginata is present just below the peristome. In common with N. eustachya, the indumentum is almost completely absent from the leaves, which are sub-petiolate and wider than those of N. albomarginata. No mature plants of this hybrid have been observed and, as such, the upper pitchers and inflorescence remain unknown.
Nepenthes eustachya × N. longifolia
Nepenthes longifolia
Nepenthes longifolia is a tropical pitcher plant endemic to Sumatra, where it grows at elevations of between 300 and 1100 m above sea level. The specific epithet longifolia, formed from the Latin words longus and folius , refers to the exceptionally large leaves of this species.-Botanical...
has been recorded from a number of locations near Payakumbuh
Payakumbuh
Payakumbuh is a city north-east of Bukittinggi , Indonesia. It has an area of 80.43 km² and a population of over 99,300 people. Literally translated, the city name means "grassy swamp"....
and Sibolga
Sibolga
Sibolga is a city and a port on the west coast of North Sumatra province, in Indonesia. It is located on the western side of North Sumatra, facing the Indian Ocean and is a transit harbour to Nias island. It was hard hit during the 2004 Indian Ocean Earthquake.- History :Poncan Ketek Island in...
, where its parent species are sympatric. It is relatively rare because N. eustachya and N. longifolia occur in markedly different habitats; the former usually grows in exposed, sunny sites, while the latter is more common in dense, shady forest. This hybrid differs from N. eustachya in having fringed lamina margins bearing short reddish-brown hairs. The peristome often has a distinctive raised section at the front, a characteristic inherited from N. longifolia. It can be distinguished from N. longifolia on the basis of its shorter tendrils and the presence of longitudinal furrows on the surface of the lamina, similar to those of N. eustachya.
In addition, putative natural hybrids with N. ampullaria
Nepenthes ampullaria
Nepenthes ampullaria , the Flask-Shaped Pitcher-Plant, is a very distinctive and widespread species of Nepenthes, present in Borneo, Sumatra, Thailand, Peninsular Malaysia, Singapore, the Maluku Islands, and New Guinea...
, N. gracilis
Nepenthes gracilis
Nepenthes gracilis , or the Slender Pitcher-Plant, is a very common lowland pitcher plant that is widespread in the Sunda region. It has been recorded from Borneo, Peninsular Malaysia, Singapore, central Sulawesi, Sumatra, and southernmost Thailand...
, and N. sumatrana
Nepenthes sumatrana
Nepenthes sumatrana is a tropical pitcher plant endemic to the Indonesian island of Sumatra, after which it is named.-Discovery and taxonomy:...
have been observed.