Nepenthes thorelii
Encyclopedia
Nepenthes thorelii is a tropical pitcher plant
endemic to Indochina
. Very little is known about N. thorelii and it is unlikely to have entered cultivation, although various other taxa
are often mislabelled as this species in the plant trade. Prior to its rediscovery in 2011, N. thorelii was considered possibly extinct
, both in the wild and in cultivation.
. During this time, Thorel collected a number of specimens of N. thorelii, all of which have been designated as Thorel 1032. One of these specimens, the lectotype
, is a male plant with lower pitchers. It is deposited at the Museum National d'Histoire Naturelle
in Paris
, together with one isotype
: a female specimen with upper pitchers. A second isotype is held at Herbarium Bogoriense (BO), the herbarium of the Bogor Botanical Gardens
. An additional specimen of Thorel 1032 is deposited at the New York Botanical Garden
.
Nepenthes thorelii was formally described
in 1909 by French
botanist Paul Henri Lecomte
, who named it after Thorel. The description was published in Lecomte's Notulae systematicae. Since then, one infraspecific taxon of N. thorelii has appeared in print; Nepenthes thorelii f. rubra was mentioned by Leo C. Song in a 1979 article published in the Carnivorous Plant Newsletter
, but is considered a nomen nudum
.
In 1983, Bruce Lee Bednar wrote that cultivated plants labelled as N. kampotiana
were thought to represent a natural hybrid between N. mirabilis
and N. thorelii, and that these appeared on some lists under the unofficial name N. × lecouflei. Bednar noted that a plant known in the horticultural
trade as "thorelii-long green" was considered by many to be a Thailand
form of N. mirabilis, while another plant called "short round", which had pubescent leaves and squat pitchers, might represent the true N. thorelii. If this were the case, it would mean that artificial crosses such as N. 'Hachijo' and N. 'Effulgent Koto' are intergrades of N. mirabilis as opposed to hybrids.
In their 1997 monograph on the genus Nepenthes, Matthew Jebb
and Martin Cheek
designated the male specimen deposited at the Paris herbarium as the lectotype of N. thorelii. The authors noted that there are "problems with the delimitation" of N. thorelii and the related taxa
N. anamensis and N. smilesii
(which are now considered conspecific).
Compounds derived from plants identified as N. thorelii have been the subject of some research. A 1998 article reported that naphthoquinone
s originating from N. thorelii showed antimalarial activity. This was followed by a paper in 2007 that studied the isozymic
composition of nepenthesin
in the pitcher fluid of a number of species, including one identified as N. thorelii.
In November 2009, photographs surfaced on the internet which appeared to show N. thorelii in its natural habitat in Vietnam, growing at 0–200 m above sea level. In February 2010, Charles Clarke
and François Mey travelled to the site where the photographs had been taken, as well as to the type location, but were unable to find any remaining plants of this species.
Nepenthes thorelii was rediscovered within a military zone in Tay Ninh Province, Vietnam, in August 2011. The so-called Sữa Đá population was found by a team including François Mey, Alastair Robinson
and Luu Hong Truong, curator of the VNM Herbarium in Ho Chi Minh City
, and was estimated to number fewer than 100 individuals. The discovery was announced online by Alastair Robinson on August 6, 2011:
that produces shoots every wet season
. The rootstock is irregularly branched and measures up to 2 cm in width.
Leaves vary in shape from linear-lanceolate to narrowly obovate. The lamina or leaf blade measures up to 26 cm in length by 3 cm in width. Its apex is acute to acuminate. The base of the lamina is amplexicaul and decurrent into two wings that extend up to 2.5 cm down the stem. The ends of these wings are rounded such that they almost touch. Two to four longitudinal veins are present on either side of the midrib. Pinnate veins are numerous and curve towards the apex of the lamina.
Rosette and lower pitchers are ovoid in shape and measure up to 11.5 cm in height by 4.5 cm in width. They are light green with reddish markings and a reddish lid. A pair of wings up to 8 mm wide runs down the front of each pitcher. These wings bear fringe elements up to 5 mm long and spaced around 2 mm apart. The pitcher mouth is ovate-triangular and has an oblique insertion. The peristome
is rounded at the front and ranges in width from 2 to 4 mm at the front to 7 mm at the rear. It bears a series of ribs spaced 0.25 to 0.4 mm apart. The inner margin of the peristome is lined with rounded teeth measuring 0.2 to 0.5 mm. The lid or operculum
is ovate to rounded in shape and up to 3.5 cm long by 2.8 cm wide. Numerous prominently lipped gland
s are present on the underside of the lid, particularly near the base of the midrib, where they are 0.3 to 0.7 mm wide. Glands become less dense and smaller (around 0.15 mm wide) towards the margins. An unbranched spur
measuring 2 to 4 mm is inserted near the base of the lid.
Upper pitchers arise from uncurled tendrils. They are obovate, becoming narrower towards the mouth. They are similar in size to their lower counterparts, reaching 12.5 cm in height by 4.5 cm in width. In aerial pitchers, the broad wings of the lower pitchers are reduced to narrow structures only 1 to 1.5 mm wide, with shorter acuminate fringe elements (≤1.5 mm long) spaced 3 to 7 mm apart. As in lower pitchers, the pitcher mouth is oblique and concave. The peristome is rounded and 3 to 5 mm wide, with a regularly undulate outer margin. The lid is similar to that of the lower pitchers.
Nepenthes thorelii has a large racemose
inflorescence
. The peduncle
is 8 to 18 cm long, while the rachis
is 50 to 70 cm long. Partial peduncles are one-flowered. Pedicels
are up to 6 mm long and may or may not be shortly bract
eate.
The species has an indumentum
of simple or branched white hairs between 0.3 and 0.4 mm long.
The diploid chromosome
number of N. thorelii is 78 according to a 1969 paper by Katsuhiko Kondo. However, a 1997 study by Günther Rudolf Heubl and Andreas Wistuba
found the chromosome number to be 80, and this is now accepted as the diploid number of all species in the genus.
, where the type specimen was collected.
Nepenthes thorelii occurs in seasonally dry savannah
grassland
from sea level to an elevation of 200 m. During the dry season
it is believed to survive as a dormant rootstock while bushfires burn any above-ground vegetation. New shoots are produced annually with the advent of the wet season
.
Since the extent of its natural range is uncertain, N. thorelii is listed as Data Deficient
on the 2006 IUCN Red List of Threatened Species
based on an assessment carried out in 2000.
Nepenthes thorelii is closely related to the Indochinese
species N. smilesii
. These two taxa
share several morphological features, such as narrow linear leaf blades and leaf bases that clasp the stem. In addition, N. smilesii may grow in similar habitats to N. thorelii.
Distinguishing features of N. thorelii include the large rootstock that allows it to perennate through dry and wet seasons, the uncurled tendrils of upper pitchers, and its large inflorescence
. However, the extent of the variation of the Indochinese species is unknown, making them difficult to circumscribe.
Nepenthes thorelii is also allied to N. bokorensis
of Cambodia
, from which it differs in several aspects of vegetative morphology. Firstly, the lamina of N. bokorensis is sessile to sub-petiolate and only slightly decurrent down the stem, if at all. In comparison, N. thorelii has an amplexicaul leaf attachment and the base of the lamina is decurrent into two wings that extend up to 2.5 cm down the stem. In addition, N. thorelii has wholly ovoid lower pitchers, whereas those of N. bokorensis are only ovate in the basal third, becoming cylindrical above.
and N. thorelii have been recorded. Both simple and complex crosses with N. mirabilis are present at the Sữa Đá site, discovered in 2011.
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 Indochina
Indochina
The Indochinese peninsula, is a region in Southeast Asia. It lies roughly southwest of China, and east of India. The name has its origins in the French, Indochine, as a combination of the names of "China" and "India", and was adopted when French colonizers in Vietnam began expanding their territory...
. Very little is known about N. thorelii and it is unlikely to have entered cultivation, although various other 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...
are often mislabelled as this species in the plant trade. Prior to its rediscovery in 2011, N. thorelii was considered possibly extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
, both in the wild and in cultivation.
Botanical history
The first known collection of N. thorelii was made by Clovis Thorel between 1862 and 1866 from Ti-tinh, Lo-thieu, Guia-Toan, VietnamVietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
. During this time, Thorel collected a number of specimens of N. thorelii, all of which have been designated as Thorel 1032. One of these specimens, 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...
, is a male plant with lower pitchers. It is deposited at the Museum National d'Histoire Naturelle
Muséum national d'histoire naturelle
The Muséum national d'Histoire naturelle is the National Museum of Natural History in Paris, France.- History :The museum was formally founded on 10 June 1793, during the French Revolution...
in Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
, together with one 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....
: a female specimen with upper pitchers. A second isotype is held at Herbarium Bogoriense (BO), 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...
. An additional specimen of Thorel 1032 is deposited at the New York Botanical Garden
New York Botanical Garden
- See also :* Education in New York City* List of botanical gardens in the United States* List of museums and cultural institutions in New York City- External links :* official website** blog*...
.
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...
in 1909 by French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
botanist Paul Henri Lecomte
Paul Henri Lecomte
Paul Henri Lecomte was a French botanist.In 1884, after attaining a number of degrees, Lecomte became a professor at Lycée Saint-Louis in Paris...
, who named it after Thorel. The description was published in Lecomte's Notulae systematicae. Since then, one infraspecific taxon of N. thorelii has appeared in print; Nepenthes thorelii f. rubra was mentioned by Leo C. Song in a 1979 article published in the Carnivorous Plant Newsletter
Carnivorous Plant Newsletter
The Carnivorous Plant Newsletter is the official publication of the International Carnivorous Plant Society , the largest such organization in the world.-History and editorship:...
, but is considered a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
.
In 1983, Bruce Lee Bednar wrote that cultivated plants labelled as N. kampotiana
Nepenthes kampotiana
Nepenthes kampotiana is a tropical pitcher plant native to southern Cambodia, eastern Thailand, and western Vietnam. The specific epithet kampotiana refers to the Cambodian city of Kampot, close to which the first specimens of this species were collected.This species is closely related to...
were thought to represent a natural hybrid between 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,...
and N. thorelii, and that these appeared on some lists under the unofficial name N. × lecouflei. Bednar noted that a plant known in the horticultural
Horticulture
Horticulture is the industry and science of plant cultivation including the process of preparing soil for the planting of seeds, tubers, or cuttings. Horticulturists work and conduct research in the disciplines of plant propagation and cultivation, crop production, plant breeding and genetic...
trade as "thorelii-long green" was considered by many to be a Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
form of N. mirabilis, while another plant called "short round", which had pubescent leaves and squat pitchers, might represent the true N. thorelii. If this were the case, it would mean that artificial crosses such as N. 'Hachijo' and N. 'Effulgent Koto' are intergrades of N. mirabilis as opposed to hybrids.
In their 1997 monograph on the genus Nepenthes, 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,...
designated the male specimen deposited at the Paris herbarium as the lectotype of N. thorelii. The authors noted that there are "problems with the delimitation" of N. thorelii and the related 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...
N. anamensis and N. smilesii
Nepenthes smilesii
Nepenthes smilesii is a tropical pitcher plant native to northeastern Thailand, southern Laos, Cambodia, and western Vietnam. Nepenthes smilesii can tolerate an extended dry season and is most common in open, sandy savannah and grassland....
(which are now considered conspecific).
Compounds derived from plants identified as N. thorelii have been the subject of some research. A 1998 article reported that naphthoquinone
Naphthoquinone
Naphthoquinone is a class of natural phenols based on the C6-C4 skeleton.1,4-Naphthoquinone can be viewed as derivatives of naphthalene through the replacement of two hydrogen atoms by two ketone groups....
s originating from N. thorelii showed antimalarial activity. This was followed by a paper in 2007 that studied the isozymic
Isozyme
Isozymes are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters Isozymes (also known as isoenzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes...
composition of nepenthesin
Nepenthesin
Nepenthesin is an aspartic protease of plant origin that has so far been identified in the pitcher secretions of Nepenthes and in the leaves of Drosera peltata. It is similar to pepsin, but differs in that it also cleaves on either side of Asp residues and at Lys┼Arg...
in the pitcher fluid of a number of species, including one identified as N. thorelii.
In November 2009, photographs surfaced on the internet which appeared to show N. thorelii in its natural habitat in Vietnam, growing at 0–200 m above sea level. In February 2010, 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...
and François Mey travelled to the site where the photographs had been taken, as well as to the type location, but were unable to find any remaining plants of this species.
Nepenthes thorelii was rediscovered within a military zone in Tay Ninh Province, Vietnam, in August 2011. The so-called Sữa Đá population was found by a team including François Mey, Alastair Robinson
Alastair Robinson
Dr. Alastair S. Robinson is a British-American taxonomist and field botanist specialising in the carnivorous plant genus Nepenthes...
and Luu Hong Truong, curator of the VNM Herbarium in Ho Chi Minh City
Ho Chi Minh City
Ho Chi Minh City , formerly named Saigon is the largest city in Vietnam...
, and was estimated to number fewer than 100 individuals. The discovery was announced online by Alastair Robinson on August 6, 2011:
As of today, Nepenthes thorelii has officially been relocated in Vietnam, within Tay Ninh province, its type locality [...] the specimens studied in situ at the so-called Sữa Đá (Sua Da) site fall neatly into the description made by Lecomte in 1909, and match the specimens at the Paris herbarium perfectly. This is therefore the first time that the species has been formally identified and collected [...] by qualified botanists in one hundred and two years. Given the recent elimination of potential communities of this taxon by poachers, details of the site will not be made public for the foreseeable future, a decision made in concert with the Institute of Tropical Biology in Ho Chi Minh -- with whom we conducted the expedition -- in order to protect this critically endangered taxon.
Description
Nepenthes thorelii is a shrub with an erect stem having a smooth circular cross section and a tapering form. The stem reaches 40 cm in height and is 4 to 8 mm in diameter. The species has a well-developed perennial rootstockRootstock
A rootstock is a plant, and sometimes just the stump, which already has an established, healthy root system, used for grafting a cutting or budding from another plant. The tree part being grafted onto the rootstock is usually called the scion...
that produces shoots every wet season
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...
. The rootstock is irregularly branched and measures up to 2 cm in width.
Rosette and lower pitchers are ovoid in shape and measure up to 11.5 cm in height by 4.5 cm in width. They are light green with reddish markings and a reddish lid. A pair of wings up to 8 mm wide runs down the front of each pitcher. These wings bear fringe elements up to 5 mm long and spaced around 2 mm apart. The pitcher mouth is ovate-triangular and has an oblique insertion. The 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...
is rounded at the front and ranges in width from 2 to 4 mm at the front to 7 mm at the rear. It bears a series of ribs spaced 0.25 to 0.4 mm apart. The inner margin of the peristome is lined with rounded teeth measuring 0.2 to 0.5 mm. 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 to rounded in shape and up to 3.5 cm long by 2.8 cm wide. Numerous prominently lipped gland
Gland
A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...
s are present on the underside of the lid, particularly near the base of the midrib, where they are 0.3 to 0.7 mm wide. Glands become less dense and smaller (around 0.15 mm wide) towards the margins. 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...
measuring 2 to 4 mm is inserted near the base of the lid.
Upper pitchers arise from uncurled tendrils. They are obovate, becoming narrower towards the mouth. They are similar in size to their lower counterparts, reaching 12.5 cm in height by 4.5 cm in width. In aerial pitchers, the broad wings of the lower pitchers are reduced to narrow structures only 1 to 1.5 mm wide, with shorter acuminate fringe elements (≤1.5 mm long) spaced 3 to 7 mm apart. As in lower pitchers, the pitcher mouth is oblique and concave. The peristome is rounded and 3 to 5 mm wide, with a regularly undulate outer margin. The lid is similar to that of the lower pitchers.
Nepenthes thorelii has a large 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 8 to 18 cm long, while 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...
is 50 to 70 cm long. Partial peduncles are one-flowered. Pedicels
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....
are up to 6 mm long and may or may not be shortly 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...
eate.
The species has an 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 simple or branched white hairs between 0.3 and 0.4 mm long.
The diploid chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
number of N. thorelii is 78 according to a 1969 paper by Katsuhiko Kondo. However, a 1997 study by Günther Rudolf Heubl and Andreas Wistuba
Andreas Wistuba
Dr. Andreas Wistuba is a German taxonomist and botanist specialising in the carnivorous plant genera Heliamphora and Nepenthes. More than half of all known Heliamphora species have been described by Wistuba.-Publications:...
found the chromosome number to be 80, and this is now accepted as the diploid number of all species in the genus.
Ecology
Nepenthes thorelii is known with certainty only from VietnamVietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
, where the type specimen was collected.
Nepenthes thorelii occurs in seasonally dry savannah
Savannah
Savannah or savanna is a type of grassland.It can also mean:-People:* Savannah King, a Canadian freestyle swimmer* Savannah Outen, a singer who gained popularity on You Tube...
grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
from sea level to an elevation of 200 m. During the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
it is believed to survive as a dormant rootstock while bushfires burn any above-ground vegetation. New shoots are produced annually with the advent of the wet season
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...
.
Since the extent of its natural range is uncertain, N. thorelii is listed as Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
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...
based on an assessment carried out in 2000.
Related species
Indochina
The Indochinese peninsula, is a region in Southeast Asia. It lies roughly southwest of China, and east of India. The name has its origins in the French, Indochine, as a combination of the names of "China" and "India", and was adopted when French colonizers in Vietnam began expanding their territory...
species N. smilesii
Nepenthes smilesii
Nepenthes smilesii is a tropical pitcher plant native to northeastern Thailand, southern Laos, Cambodia, and western Vietnam. Nepenthes smilesii can tolerate an extended dry season and is most common in open, sandy savannah and grassland....
. These 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...
share several morphological features, such as narrow linear leaf blades and leaf bases that clasp the stem. In addition, N. smilesii may grow in similar habitats to N. thorelii.
Distinguishing features of N. thorelii include the large rootstock that allows it to perennate through dry and wet seasons, the uncurled tendrils of upper pitchers, and its large 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...
. However, the extent of the variation of the Indochinese species is unknown, making them difficult to circumscribe.
Nepenthes thorelii is also allied to N. bokorensis
Nepenthes bokorensis
Nepenthes bokorensis is a tropical pitcher plant endemic to Cambodia. It is known from Mount Bokor in the south of the country, and an as yet undetermined specimen suggests that it may also be present in other parts of the Dâmrei Mountains of Kampot Province...
of Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
, from which it differs in several aspects of vegetative morphology. Firstly, the lamina of N. bokorensis is sessile to sub-petiolate and only slightly decurrent down the stem, if at all. In comparison, N. thorelii has an amplexicaul leaf attachment and the base of the lamina is decurrent into two wings that extend up to 2.5 cm down the stem. In addition, N. thorelii has wholly ovoid lower pitchers, whereas those of N. bokorensis are only ovate in the basal third, becoming cylindrical above.
Natural hybrids
Putative natural hybrids between N. mirabilisNepenthes 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,...
and N. thorelii have been recorded. Both simple and complex crosses with N. mirabilis are present at the Sữa Đá site, discovered in 2011.