Nepenthes inermis
Encyclopedia
Nepenthes inermis is a tropical pitcher plant
endemic to Sumatra
. The specific epithet inermis is Latin
for "unarmed" and probably refers to the upper pitchers of this species, which are unique in that they completely lack a peristome
.
, at an altitude of 2590 m above sea level. Two further collections were made by Bünnemeijer on Bukit Gombak on November 16, 1918, at 2300 m and 2330 m. A fourth specimen was taken on April 26, 1920, from an elevation of 1800 m on Mount Kerintji. This final specimen, Bünnemeijer 9695, was later designated as the lectotype
of N. inermis by Matthew Jebb
and Martin Cheek
.
Nepenthes inermis was first illustrated in an issue of De Tropische Natuur published in 1927. A year later, B. H. Danser
formally described
N. inermis in his seminal monograph "The Nepenthaceae of the Netherlands Indies
". He wrote: "This new species is easily distinguishable from all others by the peculiar pitchers without peristome and with very narrow lid. Probably it is most nearly related to N. Bongso."
Several of the specimens collected by Bünnemeijer were labeled with the local vernacular names galoe-galoe antoe and kandjong baroek. Danser noted that these originate from the Minangkabau language
and are also used to refer to other species, but stated that their meaning was not clear to him.
In 1986, Mitsuru Hotta
and Rusjdi Tamin included plant material belonging to N. dubia and N. inermis in their description of N. bongso
.
In a 1993 study of Nepenthes prey and pitcher infauna
, the same authors, together with M. Kato and T. Itino, identified N. inermis from Mount Gadut as N. bongso.
Despite this taxonomic confusion, N. bongso differs considerably in pitcher morphology from N. inermis and is not easily confused with it.
s are up to 10 cm long.
Leaves are sessile and coriaceous. The lamina is lanceolate-spathulate in form. It may be up to 12 cm long and 3 cm wide. It has an acute or obtuse apex and is gradually attenuate towards the base, which clasps the stem and is not decurrent. Three longitudinal veins are present on either side of the midrib. Pinnate veins are reticulate. Tendril
s can be up to 15 cm long and may or may not have a curl.
Rosette and lower pitchers are rarely produced. They are infundibular in the lower two-thirds to three-quarters, and ovoid above. They are distinctly constricted just below the peristome. Terrestrial pitchers grow to 8 cm in height and 3 cm in width. Fringed wings are usually absent, but may be present in the upper part. The pitcher mouth is round and horizontal, and raised slightly towards the rear. The peristome is cylindrical, up to 3 mm wide, and bears indistinct teeth. The lid or operculum
is ovate and lacks appendages. An unbranched spur
(≤4 mm long) is inserted at the base of the lid.
The unusual upper pitchers of N. inermis are larger than its lower pitchers, growing to 9 cm in height and 5 cm in width. They gradually or abruptly arise from the ends of the tendrils, forming a 10 to 20 mm wide curve. They are tubular to infundibular in the lower two-thirds with laterally appressed pitcher walls. As in N. dubia, there is almost no gap between the walls in mature pitchers. The upper part of the pitcher is widely infundibular throughout. Wings are reduced to ribs in upper pitchers. The mouth is round and either horizontal or slightly raised at the front and rear. The inner surface of the pitcher is glandular throughout and has no waxy zone. Mature upper pitchers completely lack a peristome, a trait that is unique to this species. The lid is very long, narrow, and cuneiform. It is never reflexed beyond 90 degrees relative to the mouth.
Nepenthes inermis has a racemose
inflorescence
. The peduncle
may be up to 5 cm long. The rachis
grows to 15 cm in length, although it is usually shorter in female inflorescences. Pedicel
s are bract
eolate and up to 8 mm long. Sepal
s are oblong-lanceolate and up to 3 mm long.
Young parts of the plant, such as developing pitchers, are covered in a dense indumentum
. However, most hairs are caducous and mature parts are virtually glabrous. An exception to this are the hairs on the ovary
and some other parts of the inflorescence, which may be persistent.
The stem, inflorescence and tendrils are characteristically purplish-red in most plants. The lamina is green, often with a red midrib. Pitchers are yellowish-green. Danser described the colour of herbarium specimens as "blackish in all parts".
Nepenthes inermis is endemic to a number peaks in the Barisan Mountains
that line the western side of Sumatra
. More specifically, it is known only from the Indonesia
n provinces of West Sumatra
and Jambi. The species has an altitudinal distribution of 1500 to 2600 m above sea level. It usually grows as an epiphyte
in mossy forest, but also occurs terrestrially in stunted upper montane vegetation above 2000 m.
Substantial populations of this species are present on Mount Talang
, Mount Gadut, and Mount Belirang. Nepenthes inermis is particularly abundant on the western slopes of the latter, where it grows terrestrially.
The conservation status
of N. inermis is listed as Vulnerable
on the 2006 IUCN Red List of Threatened Species
.
pitcher liquid. It is so viscous that if a pitcher is held upside down, the fluid will pour out, forming an unbroken stream several metres in length. This fluid coats the entire inner surfaces of the pitchers in a thin film. The pitchers of N. inermis function not only as pitfall traps but also as flypaper traps, with the sticky inner walls trapping flying insects above the surface of the fluid. The fluid also acts as a lubricant
, allowing prey items to easily slide down into the bottom of the pitcher cup.
The upper pitchers of N. inermis are frequently tipped over during downpours. The rainwater that accumulates in them is lost, but the extremely viscous fluid, together with the laterally appressed walls, ensure that the contents is retained. No longer holding heavy rainwater, the pitchers quickly spring back to an upright position. A similar trapping method may be employed by related species such as N. dubia
, which also produce very viscous pitcher fluid.
Nepenthes inermis pitchers mostly trap flying insects, particularly those of the two fly
suborders: Nematocera
and Brachycera
. However, they do not normally contain invertebrate
pitcher infauna
.
It has been suggested that glands on the lid secrete compounds that intoxicate visiting insects, such that they lose their footing and fall into the pitcher.
, N. flava
, N. jacquelineae
, N. jamban
, N. talangensis
, and N. tenuis
. These species are characterised by infundibular upper pitchers and highly viscous pitcher fluid.
Nepenthes inermis is thought to be most closely related to N. dubia
. However, it is easily distinguished from that species as it completely lacks a peristome in its upper pitchers unlike the latter. The pitchers are also usually green, while those of N. dubia tend to be yellow to orange in colour.
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.
In his description of the Bornean
species N. campanulata
, botanist Shigeo Kurata
suggested that it may be closely related to N. inermis. However, other taxonomists disagree with this hypothesis. While these two species are similar in general stature and pitcher morphology, they are not only separated by great geographical distance, but also occur in completely different habitats; N. campanulata is a lowland species endemic to limestone
substrates, where as N. inermis usually grows as an epiphyte
at elevations of 1500 to 2600 m.
on the upper slopes of Mount Talang
, where the two species grow sympatrically. N. talangensis was only described as a distinct species in 1994. Prior to this it was placed within N. bongso
and some of the older literature identifies this hybrid as N. bongso × N. inermis.
Nepenthes inermis × N. talangensis has been the subject of taxonomic confusion in the past. In an article published in 1973 on the Nepenthes of Borneo, Singapore, and Sumatra, Shigeo Kurata
incorrectly identified specimens of this hybrid as belonging to N. dubia.
In 1997, Matthew Jebb
and Martin Cheek
published their monograph "A skeletal revision of Nepenthes (Nepenthaceae)
", in which they referred to N. dubia plant material from Mount Talang
(Kurata s.n. SING). Charles Clarke
later identified Kurata s.n. as representing N. inermis × N. talangensis.
The natural hybrid is similar to N. dubia, but can be distinguished on the basis of several stable characters. The hybrid has a wider pitcher lid that is never relfexed beyond 90 degrees and the pitcher cup is not appressed in the lower parts as in N. dubia. In addition, the mouth of N. inermis × N. talangensis is raised towards the back as opposed to being horizontal.
In 2001, Kurata described this hybrid as a new species, N. pyriformis. Clarke rejected this interpretation in his monograph Nepenthes of Sumatra and Peninsular Malaysia
, published the same year. Clarke found that the type specimen of N. pyriformis, Kurata & Mikil 4230 NDC, matches the appearance of N. inermis × N. talangensis "in most respects".
and N. spathulata
.
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...
. The specific epithet inermis is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "unarmed" and probably refers to the upper pitchers of this species, which are unique in that they completely lack a 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...
.
Botanical history
Nepenthes inermis was first collected on September 7, 1918, by H. A. B. Bünnemeijer on Mount TalangMount Talang
Mount Talang is an active stratovolcano in West Sumatra, Indonesia. Talang has two crater lakes on its flanks, the largest of which is 1 x 2 km wide and is called Lake Talang....
, at an altitude of 2590 m above sea level. Two further collections were made by Bünnemeijer on Bukit Gombak on November 16, 1918, at 2300 m and 2330 m. A fourth specimen was taken on April 26, 1920, from an elevation of 1800 m on Mount Kerintji. This final specimen, Bünnemeijer 9695, was later 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. inermis 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,...
.
B. H. Danser
Benedictus Hubertus Danser , often abbreviated B. H. Danser, was a Dutch taxonomist and botanist...
formally described
Species description
A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...
N. inermis 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...
". He wrote: "This new species is easily distinguishable from all others by the peculiar pitchers without peristome and with very narrow lid. Probably it is most nearly related to N. Bongso."
Several of the specimens collected by Bünnemeijer were labeled with the local vernacular names galoe-galoe antoe and kandjong baroek. Danser noted that these originate from the Minangkabau language
Minangkabau language
The Minangkabau language is an Austronesian language, spoken by the Minangkabau of West Sumatra, the western part of Riau, South Aceh Regency, the northern part of Bengkulu and Jambi, also in several cities throughout Indonesia by migrated Minangkabau, who often trade or have a restaurant...
and are also used to refer to other species, but stated that their meaning was not clear to him.
In 1986, 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 included plant material belonging to N. dubia and N. inermis in their description of N. bongso
Nepenthes bongso
Nepenthes bongso is a tropical pitcher plant endemic to Sumatra, where it has an altitudinal distribution of 1000–2700 m above sea level. The specific epithet bongso refers to the Indonesian legend of Putri Bungsu , the spirit guardian of Mount Marapi.The species was formally described by Pieter...
.
In a 1993 study of Nepenthes prey and pitcher infauna
Nepenthes infauna
Nepenthes infauna are the organisms that inhabit the pitchers of Nepenthes plants. These include fly and midge larvae, spiders, mites, ants, and even a species of crab, Geosesarma malayanum. The most common and conspicuous predators found in pitchers are mosquito larvae, which consume large...
, the same authors, together with M. Kato and T. Itino, identified N. inermis from Mount Gadut as N. bongso.
Despite this taxonomic confusion, N. bongso differs considerably in pitcher morphology from N. inermis and is not easily confused with it.
Description
Nepenthes inermis is a climbing plant. The stem can reach 5 m in length and is up to 5 mm in diameter. It is cylindrical-triangular in cross section. 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 up to 10 cm long.
Leaves are sessile and coriaceous. The lamina is lanceolate-spathulate in form. It may be up to 12 cm long and 3 cm wide. It has an acute or obtuse apex and is gradually attenuate towards the base, which clasps the stem and is not decurrent. Three longitudinal veins are present on either side of the midrib. Pinnate veins are reticulate. 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 can be up to 15 cm long and may or may not have a curl.
Rosette and lower pitchers are rarely produced. They are infundibular in the lower two-thirds to three-quarters, and ovoid above. They are distinctly constricted just below the peristome. Terrestrial pitchers grow to 8 cm in height and 3 cm in width. Fringed wings are usually absent, but may be present in the upper part. The pitcher mouth is round and horizontal, and raised slightly towards the rear. The peristome is cylindrical, up to 3 mm wide, and bears indistinct teeth. The lid or operculum
Operculum (botany)
An operculum, in botany, is a term generally used to describe a structure within a plant, moss, or fungus acting as a cap, flap, or lid. In plants, it may also be called a bud cap.Examples of structures identified as opercula include:...
is ovate and lacks appendages. An unbranched 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...
(≤4 mm long) is inserted at the base of the lid.
The unusual upper pitchers of N. inermis are larger than its lower pitchers, growing to 9 cm in height and 5 cm in width. They gradually or abruptly arise from the ends of the tendrils, forming a 10 to 20 mm wide curve. They are tubular to infundibular in the lower two-thirds with laterally appressed pitcher walls. As in N. dubia, there is almost no gap between the walls in mature pitchers. The upper part of the pitcher is widely infundibular throughout. Wings are reduced to ribs in upper pitchers. The mouth is round and either horizontal or slightly raised at the front and rear. The inner surface of the pitcher is glandular throughout and has no waxy zone. Mature upper pitchers completely lack a peristome, a trait that is unique to this species. The lid is very long, narrow, and cuneiform. It is never reflexed beyond 90 degrees relative to the mouth.
Nepenthes inermis 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...
may be up to 5 cm long. 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...
grows to 15 cm in length, although it is usually shorter in female inflorescences. Pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
s are 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...
eolate and up to 8 mm long. 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 oblong-lanceolate and up to 3 mm long.
Young parts of the plant, such as developing pitchers, are covered in a dense 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...
. However, most hairs are caducous and mature parts are virtually glabrous. An exception to this are the hairs on the ovary
Ovary (plants)
In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
and some other parts of the inflorescence, which may be persistent.
The stem, inflorescence and tendrils are characteristically purplish-red in most plants. The lamina is green, often with a red midrib. Pitchers are yellowish-green. Danser described the colour of herbarium specimens as "blackish in all parts".
Ecology
Barisan Mountains
The Bukit Barisan or the Barisan Mountains are a mountain range on the western side of Sumatra, Indonesia, covering nearly 1,700 km from the north to the south of the island. The Bukit Barisan range consists primarily of volcanoes shrouded in dense jungle cover, including Sumatran tropical pine...
that line the western side of 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...
. More specifically, it is known only from the Indonesia
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 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...
and Jambi. The species has an altitudinal distribution of 1500 to 2600 m above sea level. It usually grows as an epiphyte
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
in mossy forest, but also occurs terrestrially in stunted upper montane vegetation above 2000 m.
Substantial populations of this species are present on Mount Talang
Mount Talang
Mount Talang is an active stratovolcano in West Sumatra, Indonesia. Talang has two crater lakes on its flanks, the largest of which is 1 x 2 km wide and is called Lake Talang....
, Mount Gadut, and Mount Belirang. Nepenthes inermis is particularly abundant on the western slopes of the latter, where it grows terrestrially.
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. inermis is listed as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
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...
.
Carnivory
Nepenthes inermis produces extremely thick mucilaginousMucilage
Mucilage is a thick, gluey substance produced by most plants and some microorganisms. It is a polar glycoprotein and an exopolysaccharide.It occurs in various parts of nearly all classes of plant, usually in relatively small percentages, and is frequently associated with other substances, such as...
pitcher liquid. It is so viscous that if a pitcher is held upside down, the fluid will pour out, forming an unbroken stream several metres in length. This fluid coats the entire inner surfaces of the pitchers in a thin film. The pitchers of N. inermis function not only as pitfall traps but also as flypaper traps, with the sticky inner walls trapping flying insects above the surface of the fluid. The fluid also acts as a lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
, allowing prey items to easily slide down into the bottom of the pitcher cup.
The upper pitchers of N. inermis are frequently tipped over during downpours. The rainwater that accumulates in them is lost, but the extremely viscous fluid, together with the laterally appressed walls, ensure that the contents is retained. No longer holding heavy rainwater, the pitchers quickly spring back to an upright position. A similar trapping method may be employed by related species such as N. dubia
Nepenthes dubia
Nepenthes dubia is a tropical pitcher plant endemic to Sumatra. The specific epithet dubia is the Latin word for "doubtful".-Botanical history:...
, which also produce very viscous pitcher fluid.
Nepenthes inermis pitchers mostly trap flying insects, particularly those of the two fly
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
suborders: Nematocera
Nematocera
Nematocera , is a suborder of elongated flies with thin, segmented antennae and mostly aquatic larvae, consisting of the mosquitoes, crane flies, gnats, and midges....
and Brachycera
Brachycera
Brachycera is a suborder of Diptera. It is a major suborder consisting of around 120 families. The most distinguishing characteristic of the suborder is reduced antenna segmentation...
. However, they do not normally contain invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
pitcher infauna
Nepenthes infauna
Nepenthes infauna are the organisms that inhabit the pitchers of Nepenthes plants. These include fly and midge larvae, spiders, mites, ants, and even a species of crab, Geosesarma malayanum. The most common and conspicuous predators found in pitchers are mosquito larvae, which consume large...
.
It has been suggested that glands on the lid secrete compounds that intoxicate visiting insects, such that they lose their footing and fall into the pitcher.
Related species
Nepenthes inermis belongs to a group of closely related montane Sumatran species that includes N. dubiaNepenthes dubia
Nepenthes dubia is a tropical pitcher plant endemic to Sumatra. The specific epithet dubia is the Latin word for "doubtful".-Botanical history:...
, N. flava
Nepenthes flava
Nepenthes flava is a tropical pitcher plant endemic to northern Sumatra, where it grows in montane forest at 1800–2200 m above sea level....
, N. jacquelineae
Nepenthes jacquelineae
Nepenthes jacquelineae is a tropical pitcher plant endemic to Sumatra. Due to its unique pitcher morphology, it is considered to be one of the most spectacular Nepenthes species native to the island.-Botanical history:...
, N. jamban
Nepenthes jamban
Nepenthes jamban is a tropical pitcher plant endemic to northern Sumatra. The specific epithet jamban is the Indonesian word for "toilet" and refers to the shape of the pitchers.-Botanical history:...
, N. talangensis
Nepenthes talangensis
Nepenthes talangensis is a tropical pitcher plant endemic to Sumatra, where it grows in upper montane forest at elevations of 1800–2500 m above sea level....
, and N. tenuis
Nepenthes tenuis
Nepenthes tenuis is a tropical pitcher plant endemic to Sumatra. The species was first collected in 1957, from a remote mountain in the western part of the island. It remained undescribed until 1994, and was only rediscovered in the wild in 2002. Prior to this, N...
. These species are characterised by infundibular upper pitchers and highly viscous pitcher fluid.
Nepenthes inermis is thought to be most closely related to N. dubia
Nepenthes dubia
Nepenthes dubia is a tropical pitcher plant endemic to Sumatra. The specific epithet dubia is the Latin word for "doubtful".-Botanical history:...
. However, it is easily distinguished from that species as it completely lacks a peristome in its upper pitchers unlike the latter. The pitchers are also usually green, while those of N. dubia tend to be yellow to orange in colour.
In 2001, 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...
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 part 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 1", which has 51% bootstrap support. Its most strongly supported subclade is the sister pair of N. inermis and N. dubia, having 95% support.
In his description of the Bornean
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....
species N. campanulata
Nepenthes campanulata
Nepenthes campanulata , the Bell-Shaped Pitcher-Plant, is a tropical pitcher plant endemic to Borneo.Forest fires destroyed the only known population of N. campanulata in 1983 and it was uncertain whether the species had survived elsewhere or was in fact extinct. It was rediscovered in 1997,...
, botanist 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....
suggested that it may be closely related to N. inermis. However, other taxonomists disagree with this hypothesis. While these two species are similar in general stature and pitcher morphology, they are not only separated by great geographical distance, but also occur in completely different habitats; N. campanulata is a lowland species endemic to limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
substrates, where as N. inermis usually grows as an epiphyte
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
at elevations of 1500 to 2600 m.
Nepenthes × pyriformis
Nepenthes inermis is known to hybridise with N. talangensisNepenthes talangensis
Nepenthes talangensis is a tropical pitcher plant endemic to Sumatra, where it grows in upper montane forest at elevations of 1800–2500 m above sea level....
on the upper slopes of Mount Talang
Mount Talang
Mount Talang is an active stratovolcano in West Sumatra, Indonesia. Talang has two crater lakes on its flanks, the largest of which is 1 x 2 km wide and is called Lake Talang....
, where the two species grow sympatrically. N. talangensis was only described as a distinct species in 1994. Prior to this it was placed within N. bongso
Nepenthes bongso
Nepenthes bongso is a tropical pitcher plant endemic to Sumatra, where it has an altitudinal distribution of 1000–2700 m above sea level. The specific epithet bongso refers to the Indonesian legend of Putri Bungsu , the spirit guardian of Mount Marapi.The species was formally described by Pieter...
and some of the older literature identifies this hybrid as N. bongso × N. inermis.
Nepenthes inermis × N. talangensis has been the subject of taxonomic confusion in the past. In an article published in 1973 on the Nepenthes of Borneo, Singapore, and Sumatra, 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....
incorrectly identified specimens of this hybrid as belonging to N. dubia.
In 1997, 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,...
published their monograph "A skeletal revision of Nepenthes (Nepenthaceae)
A skeletal revision of Nepenthes (Nepenthaceae)
"A skeletal revision of Nepenthes " is a monograph by Matthew Jebb and Martin Cheek on the tropical pitcher plants of the genus Nepenthes. It was published in the May 1997 issue of the botanical journal Blumea. The work represented the first revision of the entire genus since John Muirhead...
", in which they referred to N. dubia plant material from Mount Talang
Mount Talang
Mount Talang is an active stratovolcano in West Sumatra, Indonesia. Talang has two crater lakes on its flanks, the largest of which is 1 x 2 km wide and is called Lake Talang....
(Kurata s.n. SING). 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...
later identified Kurata s.n. as representing N. inermis × N. talangensis.
The natural hybrid is similar to N. dubia, but can be distinguished on the basis of several stable characters. The hybrid has a wider pitcher lid that is never relfexed beyond 90 degrees and the pitcher cup is not appressed in the lower parts as in N. dubia. In addition, the mouth of N. inermis × N. talangensis is raised towards the back as opposed to being horizontal.
In 2001, Kurata described this hybrid as a new species, N. pyriformis. Clarke rejected this interpretation in his 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...
, published the same year. Clarke found that the type specimen of N. pyriformis, Kurata & Mikil 4230 NDC, matches the appearance of N. inermis × N. talangensis "in most respects".
Other hybrids
Where their ranges overlap, N. inermis is also known to hybridise with N. singalanaNepenthes singalana
Nepenthes singalana is a highland Nepenthes pitcher plant species native to the island of Sumatra. It is most closely related to N. diatas and N. spathulata.-Taxonomy:...
and N. spathulata
Nepenthes spathulata
Nepenthes spathulata is a tropical pitcher plant native to Java and Sumatra, where it grows at elevations of between 1100 and 2900 m above sea level. The specific epithet spathulata is derived from the Latin word spathulatus, meaning "spatula shaped", and refers to the shape of the...
.