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''Pinguicula'', commonly known as the butterworts, is a genus of carnivorous
flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s in the family
Lentibulariaceae Lentibulariaceae is a family of carnivorous plants containing three genera: ''Genlisea'', the corkscrew plants; ''Pinguicula'', the butterworts; and ''Utricularia'', the bladderworts. The genera ''Polypompholyx'' (two species of pink petticoats ...
. They use sticky, glandular leaves to lure, trap, and digest insects in order to supplement the poor mineral nutrition they obtain from the environment. Of the roughly 80 currently known species, 13 are native to Europe, 9 to North America, and some to northern Asia. The largest number of species is in South and Central America.


Etymology

The name ''Pinguicula'' is derived from a term coined by
Conrad Gesner Conrad Gessner (; la, Conradus Gesnerus 26 March 1516 – 13 December 1565) was a Swiss physician, naturalist, bibliographer, and philologist. Born into a poor family in Zürich, Switzerland, his father and teachers quickly realised his tale ...
, who in his 1561 work entitled ''Horti Germaniae'' commented on the glistening leaves: ''"propter pinguia et tenera folia…"'' (Latin ''pinguis'', "fat"). The common name "butterwort" reflects this characteristic.


Characteristics

The majority of ''Pinguicula'' are
perennial plant A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
s. The only known annuals are ''P. sharpii'', ''P. takakii'', ''P. crenatiloba'', and ''P. pumila''. All species form stemless rosettes.


Habitat

Butterworts can be divided roughly into two main groups based on the climate in which they grow; each group is then further subdivided based on morphological characteristics. Although these groups are not
cladistically Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...
supported by genetic studies, these groupings are nonetheless convenient for horticultural purposes. Tropical butterworts either form somewhat compact winter rosettes composed of fleshy leaves or retain carnivorous leaves year-round. They are typically located in regions where water is least seasonally plentiful, as too damp soil conditions can lead to rotting. They are found in areas in which  nitrogenous resources are known to be in low levels, infrequent or unavailable, due to acidic soil conditions.
Temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...
species often form tight buds (called hibernacula) composed of scale-like leaves during a winter dormancy period. During this time the roots (with the exception of ''P. alpina'') and carnivorous leaves wither. Temperate species flower when they form their summer rosettes while tropical species flower at each rosette change. Many butterworts cycle between rosettes composed of carnivorous and non-carnivorous leaves as the seasons change, so these two ecological groupings can be further divided according to their ability to produce different leaves during their growing season. If the growth in the summer is different in size or shape to that in the early spring (for temperate species) or in the winter (tropical species), then plants are considered
heterophyllous Heteroblasty is the significant and abrupt change in form and function, that occurs over the lifespan of certain plants. Characteristics affected include internode length and stem structure as well as leaf form, size and arrangement. It should no ...
; whereas uniform growth identifies a homophyllous species. This results in four groupings: *Tropical butterworts: species which do not undergo a winter dormancy but continue to alternately bloom and form rosettes. **''Heterophyllous tropical species'': species that alternate between rosettes of carnivorous leaves during the warm season and compact rosettes of fleshy non-carnivorous leaves during the cool season. Examples include ''P. moranensis'', ''P. gypsicola'', and ''P. laxifolia''. **''Homophyllous tropical species'': these species produce rosettes of carnivorous leaves of roughly uniform size throughout the year, such as ''P. gigantea''. *Temperate butterworts: these plants are native to climate zones with cold winters. They produce a winter-resting bud ( hibernaculum) during the winter. **''Heterophyllous temperate species'': species where the vegetative and generative rosettes differ in shape and/or size, as seen in ''P. lutea'' and ''P. lusitanica''. **''Homophyllous temperate species'': the vegetative and generative rosettes appear identical, as exhibited by ''P. alpina'', ''P. grandiflora'', and ''P. vulgaris''.


Roots

The
root system In mathematics, a root system is a configuration of vectors in a Euclidean space satisfying certain geometrical properties. The concept is fundamental in the theory of Lie groups and Lie algebras, especially the classification and representatio ...
of ''Pinguicula'' species is relatively undeveloped. The thin, white roots serve mainly as an anchor for the plant and to absorb moisture (nutrients are absorbed through carnivory). In temperate species these roots wither (except in ''P. alpina'') when the hibernaculum is formed. In the few
epiphytic An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...
species (such as ''P. lignicola''), the roots form anchoring suction cups.


Leaves and carnivory

The leaf blade of a butterwort is smooth, rigid, and succulent, usually bright green or pinkish in colour. Depending on species, the leaves are between 2 and 30 cm (1-12") long. The leaf shape depends on the species, but is usually roughly
obovate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...
,
spatulate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...
, or
linear Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear ...
. They can also appear yellow in color with a soft feel and a greasy consistency to the leaves. Like all members of the family
Lentibulariaceae Lentibulariaceae is a family of carnivorous plants containing three genera: ''Genlisea'', the corkscrew plants; ''Pinguicula'', the butterworts; and ''Utricularia'', the bladderworts. The genera ''Polypompholyx'' (two species of pink petticoats ...
, butterworts are carnivorous. The mechanistic actions that these plants use to lure and capture prey is through a means of sticky or adhesives substances that are produced by mucilage secreted by glands located on the leaf's surface. In order to catch and digest insects, the leaf of a butterwort uses two specialized glands which are scattered across the leaf surface (usually only on the upper surface, with the exception of ''P. gigantea'' and '' P. longifolia ssp. longifolia''). One is termed a ''peduncular gland'', and consists of a few secretory cells on top of a single stalk cell. These cells produce a
mucilaginous Mucilage is a thick, gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists which use it for their locomotion. The direction of their movement is always opposite to that of the secretion of ...
secretion which forms visible droplets across the leaf surface. This wet appearance probably helps lure prey in search of water (a similar phenomenon is observed in the sundews). The droplets secrete limited amounts of digestive enzymes, and serve mainly to entrap insects. On contact with an insect, the peduncular glands release additional mucilage from special reservoir cells located at the base of their stalks. The insect will begin to struggle, triggering more glands and encasing itself in mucilage. Some species can bend their leaf edges slightly by
thigmotropism Thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however plant biologists have also found thigmotropic responses in flowe ...
, bringing additional glands into contact with the trapped insect. The second type of gland found on butterwort leaves are ''sessile glands'' which lie flat on the leaf surface. Once the prey is entrapped by the peduncular glands and digestion begins, the initial flow of nitrogen triggers enzyme release by the sessile glands. These enzymes, which include
amylase An amylase () is an enzyme that catalyses the hydrolysis of starch (Latin ') into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of ...
,
esterase An esterase is a hydrolase enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis. A wide range of different esterases exist that differ in their substrate specificity, their protein structure ...
, phosphatase,
protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
, and
ribonuclease Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within ...
break down the digestible components of the insect body. These fluids are then absorbed back into the leaf surface through
cuticular A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...
holes, leaving only the chitin
exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...
of the larger insects on the leaf surface. The holes in the cuticle which allow for this digestive mechanism also pose a challenge for the plant, since they serve as breaks in the cuticle (waxy layer) that protects the plant from desiccation. As a result, most butterworts live in humid environments. Butterworts are usually only able to trap small insects and those with large wing surfaces. They can also digest pollen which lands on their leaf surface. The secretory system can only function a single time, so that a particular area of the leaf surface can only be used to digest insects once. Unlike many other carnivorous plant species, butterworts do not appear to use
jasmonates Jasmonate (JA) and its derivatives are lipid-based plant hormones that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herb ...
as a control system to switch on the production of digestive enzymes. Jasmonates are involved in the butterwort’s defense against attacking insects, but not in its response to prey. Of the eight enzymes identified in the digestive secretions of butterworts,
alpha-amylase α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose: :Endohyd ...
appears to be unique when compared to other carnivorous plants. This research suggests that butterwort may have co-opted a different set of genes in its development of carnivory.


Flowers

As with almost all
carnivorous plants Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants still generate some of their energy from photosynthesis ...
, the flowers of butterworts are held far above the rest of the plant by a long stalk, in order to reduce the probability of trapping potential pollinators. The single, long-lasting flowers are
zygomorphic Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts. Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...
, with two lower lip petals characteristic of the bladderwort family, and a spur extending from the back of the flower. The calyx has five sepals, and the petals are arranged in a two-part lower lip and a three-part upper lip. Most butterwort flowers are blue, violet or white, often suffused with a yellow, greenish or reddish tint. '' P. laueana'' and the newly described ''P. caryophyllacea'' are unique in having a strikingly red flowers. Butterworts are often cultivated and hybridized primarily for their flowers. The shape and colors of butterwort flowers are distinguishing characteristics which are used to divide the genus into subgenera and to distinguish individual species from one another.


Fruit and seed

The round to egg-shaped seed capsules open when dry into two halves, exposing numerous small (0.5–1 mm), brown seeds. If moisture is present the
silique A silique or siliqua (plural ''siliques'' or ''siliquae'') is a type of fruit (seed capsule) having two fused carpels with the length being more than three times the width. When the length is less than three times the width of the dried fruit i ...
closes, protecting the seed and opening again upon dryness to allow for
wind dispersal Biological dispersal refers to both the movement of individuals (animals, plants, fungi, bacteria, etc.) from their birth site to their breeding site ('natal dispersal'), as well as the movement from one breeding site to another ('breeding dis ...
. Many species have a net-like pattern on their seed surface to allow them to land on water surfaces without sinking, since many non-epiphytic butterworts grow near water sources. The haploid
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
number of butterworts is either n = 8 or n = 11 (or a multiple thereof), depending on species. The exception is '' P. lusitanica'', whose chromosome count is n = 6.


Diet

The diet will range depending on the taxonomy and size of the prey due to the plant's retention ability. These size limitations are known to be the main element influencing what prey sources this carnivorous plant can access They can also acquire nourishment from pollen and other plant parts that are high in protein, as other plants can become trapped on their leaves, thus, butterworts are both carnivorous and herbivorous plants. The diet consists of several species from the arthropod taxa, majority of their prey are insects that have wings and are able to fly. The luring, retaining, and seizing of prey is the first steps in the feeding procedure for carnivorous plants; the result of the process is absorption and digestion of nutrients sourced from these food supplies. Pinguicula species do not select their prey, as they passively accumulate them through methods of sticky, adhesive leaves. However, they do have the ability of visual attraction of their colorful leaves, which will increase the likelihood of luring and capturing a specific taxa. Pinguicula capture their food source/ prey by means of the mucilaginous, sticky substances produced by their stalk glands on the top of their leaf. Once the prey has become trapped in the peduncular glands, the sessile glands present will then produce enzymes needed to accomplish digestion and breaking down the digestible regions of the  prey for their nutrients; taking in the fluids of the food source by means of cuticular holes present on the leaf's surface.


Vegetative propagation

As well as
sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote th ...
by seed, many butterworts can reproduce asexually by
vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...
. Many members of the genus form offshoots during or shortly after flowering (''e.g.'', '' P. vulgaris''), which grow into new genetically identical adults. A few other species form new offshoots using stolons (''e.g.'', '' P. calyptrata'', '' P. vallisneriifolia'') while others form plantlets at the leaf margins (''e.g.'', '' P. heterophylla'', '' P. primuliflora'').


Distribution

Butterworts are distributed throughout the northern hemisphere
map
. The greatest concentration of species, however, is in humid mountainous regions of Central America (including Mexico) and South America, where populations can be found as far south as
Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla ...
. Australia and Antarctica are the only continents without any native butterworts. Butterworts probably originated in Central America, as this is the center of ''Pinguicula'' diversity – roughly 50% of butterwort species are found here. The great majority of individual ''Pinguicula'' species have a very limited
distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations * Probability distribution, the probability of a particular value or value range of a vari ...
. The two butterwort species with the widest distribution - '' P. alpina'' and '' P. vulgaris'' - are found throughout much of Europe and North America. Other species found in North America include '' P. caerulea'', '' P. ionantha'', '' P. lutea'', '' P. macroceras'', '' P. planifolia'', '' P. primuliflora'', '' P. pumila'', and '' P. villosa''.


Habitat

In general, butterworts grow in nutrient-poor, alkaline soils. Some species have adapted to other soil types, such as acidic
peat bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
s (ex. '' P. vulgaris'', '' P. calyptrata'', '' P. lusitanica''), soils composed of pure
gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywal ...
('' P. gypsicola'' and other Mexican species), or even vertical rock walls ('' P. ramosa'', '' P. vallisneriifolia'', and most of the Mexican species). A few species are epiphytes ('' P. casabitoana'', '' P. hemiepiphytica'', '' P. lignicola''). Many of the Mexican species commonly grow on mossy banks, rock, and roadsides in oak-pine forests. ''Pinguicula macroceras ssp. nortensis'' has even been observed growing on hanging dead grasses. '' P. lutea'' grows in pine
flatwoods Flatwoods, pineywoods, pine savannas and longleaf pine-wiregrass ecosystem are terms that refer to an ecological community in the southeastern coastal plain of North America. Flatwoods are an ecosystem maintained by wildfire or prescribed fire and ...
. Other species, such as '' P. vulgaris'', grow in
fen A fen is a type of peat-accumulating wetland fed by mineral-rich Groundwater, ground or surface water. It is one of the main types of wetlands along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as ...
s. Each of these environments is nutrient-poor, allowing butterworts to escape competition from other canopy-forming species, particularly grasses and sedges. Butterworts need habitats that are almost constantly moist or wet, at least during their carnivorous growth stage. Many Mexican species lose their carnivorous leaves, and sprout succulent leaves, or die back to onion-like "bulbs" to survive the winter drought, at which point they can survive in bone-dry conditions. The moisture they need for growing can be supplied by either a high
groundwater table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...
, or by high humidity or high precipitation. Unlike many other carnivorous plants that require sunny locations, many butterworts thrive in part-sun or even shady conditions.


Conservation status

The environmental threats faced by various ''Pinguicula'' species depend on their location and on how widespread their distribution is. Most endangered are the species which are
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to small areas, such as '' P. ramosa'', '' P. casabitoana'', and '' P. fiorii''. These populations are threatened primarily by
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
.
Wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...
destruction has threatened several US species. Most of these are federally listed as either threatened or endangered, and '' P. ionantha'' is listed on
CITES CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
appendix I, giving it additional protection.


Botanical history

The first mention of butterworts in botanical literature is an entry entitle

("lard herb") by Vitus Auslasser in his 1479 work on medicinal herbs entitled ''Macer de Herbarium''. The name is still used for butterworts in
Tirol Tyrol (; historically the Tyrole; de-AT, Tirol ; it, Tirolo) is a historical region in the Alps - in Northern Italy and western Austria. The area was historically the core of the County of Tyrol, part of the Holy Roman Empire, Austrian Emp ...
, Austria. In 1583, Clusius already distinguished between two forms in his ''Historia stirpium rariorum per Pannoniam, Austriam'': a blue-flowered form ('' P. vulgaris'') and a white-flowered form (''
Pinguicula alpina ''Pinguicula alpina'', also known as the alpine butterwort, is a species of carnivorous plant native to high latitudes and altitudes throughout Eurasia. It is one of the most widespread ''Pinguicula'' species, being found in mountainous regions ...
'').
Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
added '' P. villosa'' and '' P. lusitanica'' when he published his '' Species Plantarum'' in 1753. The number of known species rose sharply with the exploration of the new continents in the 19th century; by 1844, 32 species were known. It was only in the late 19th century that the carnivory of this genus began to be studied in detail. In a letter to Asa Gray dated June 3, 1874,
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
mentioned his early observations of the butterwort's digestive process and insectivorous nature. Darwin studied these plants extensively. S. J. Casper's large 1966 monograph of the genus included 46 species, a number which has almost doubled since then. Many exciting discoveries have been made in recent years, especially in Mexico. Another important development in the history of butterworts is the formation of the
International Pinguicula Study Group The ''International Pinguicula Study Group Newsletter'' was the official publication of the International ''Pinguicula'' Study Group, a ''Pinguicula'' society based in the United Kingdom that was active during the 1990s.cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s ''Pinguicula'' × 'Sethos' and ''Pinguicula'' × 'Weser'. Both are crosses of '' Pinguicula ehlersiae'' and ''
Pinguicula moranensis ''Pinguicula moranensis'' is a perennial rosette-forming insectivorous herb native to Mexico and Guatemala. A species of butterwort, it forms summer rosettes of flat, succulent leaves up to 10 centimeters (4 in) long, which are ...
'', and are employed by commercial
orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowerin ...
nurseries to combat pests. Butterworts also produce a strong bactericide which prevents insects from rotting while they are being digested. According to
Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
, this property has long been known by northern Europeans, who applied butterwort leaves to the sores of cattle to promote healing. Additionally, butterwort leaves were used to
curdle Curdling is the breaking of an emulsion or colloid into large parts of different composition through the physio-chemical processes of flocculation, creaming, and coalescence. Curdling is purposeful in the production of cheese curd and tofu; und ...
milk and form a buttermilk-like
fermented milk product Fermented milk products or fermented dairy products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria such as ''Lactobacillus'', '' Lactococ ...
called (Sweden) and (Norway).


Classification

''Pinguicula'' belong to the Bladderwort family (
Lentibulariaceae Lentibulariaceae is a family of carnivorous plants containing three genera: ''Genlisea'', the corkscrew plants; ''Pinguicula'', the butterworts; and ''Utricularia'', the bladderworts. The genera ''Polypompholyx'' (two species of pink petticoats ...
), along with ''
Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...
'' and ''
Genlisea ''Genlisea'' ( ) is a genus of carnivorous plants also known as corkscrew plants. The 30 or so species grow in wet terrestrial to semi-aquatic environments distributed throughout Africa and Central and South America. The plants use highly modifi ...
''.
Siegfried Jost Casper Siegfried Jost Casper (12 January 1929 – 13 June 2021) was a German biologist whose primary research was in limnology and the plant genus ''Pinguicula'' (the butterworts). Together with Heinz-Dieter Krausch he published a basic reference work on ...
systematically divided them into three subgenera with 15 sections. A detailed study of the phylogenetics of butterworts by Cieslak ''et al.'' (2005) found that all of the currently accepted subgenera and many of the sections were
polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...
. The diagram below gives a more accurate representation of the correct
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
. Polyphyletic sections are marked with an *. ┌────Clade I (Sections Temnoceras *, Orcheosanthus *, Longitubus, │ Heterophyllum *, Agnata *, Isoloba *, Crassifolia) │ ┌───┤ │ │ │ │ ┌──────┤ └────Clade II (Section Micranthus * = ''P. alpina'') │ │ │ │ ┌───┤ └────────Clade III (Sections Micranthus *, Nana) │ │ │ │ ───┤ └───────────────Clade IV (Section Pinguicula) │ │ └───────────────────Clade V (Sections Isoloba *, Ampullipalatum, Cardiophyllum)


References

Much of the content of this article comes from the equivalent German-language Wikipedia article (retrieved March 29, 2009).


Further reading

* * * Keddy, P.A. (2010). Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. * Givnish, T. J. (1988). Ecology and evolution of carnivorous plants. In Plant–Animal Interactions, ed. W. B. Abrahamson, pp. 243–90. New York: McGraw-Hill.


External links

* *
An exhaustive website on the genus ''Pinguicula''
* Schlauer, J
Carnivorous Plant Database
version 15 November 16: 25.
Flora Europaea: ''Pinguicula'' species list

Botanical Society of America, ''Pinguicula'' - the Butterworts
{{Authority control Carnivorous plants of Africa Carnivorous plants of Asia Carnivorous plants of Central America Carnivorous plants of Europe Carnivorous plants of North America Carnivorous plants of South America Lamiales genera