''Drosera'', which is commonly known as the sundews, is one of the largest

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

of carnivorous plants, with at least 194

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. 2 volumes. These members of the family

Droseraceae Droseraceae is a family of carnivorous flowering plants, also known as the sundew family. It consists of approximately 180 species in three extant genera, the vast majority being in the sundew genus '' Drosera''. The family also contains the wel ...

lure, capture, and digest insects using stalked

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, with the direction of their movement always opposite to that of the secretion of ...

glands covering their leaf surfaces. The insects are used to supplement the poor mineral nutrition of the soil in which the plants grow. Various species, which vary greatly in size and form, are native to every continent except

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

performed much of the early research into ''Drosera'', engaging in a long series of experiments with '' Drosera rotundifolia'' which were the first to confirm carnivory in plants. In an 1860 letter, Darwin wrote, “…at the present moment, I care more about ''Drosera'' than the origin of all the species in the world.”

Taxonomy

The botanical name from the Greek ''drosos'' "dew, dewdrops" refer to the glistening drops of

mucilage Mucilage is a thick gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists which use it for their locomotion, with the direction of their movement always opposite to that of the secretion of ...

at the tip of the glandular

trichome Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

s that resemble drops of morning

dew Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening due to condensation. As the exposed surface cools by thermal radiation, radiating its heat, atmospheric moisture condenses at a rate grea ...

. The English common name ''sundew'' also describes this, derived from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''ros solis'' meaning "dew of the sun". The ''Principia Botanica'', published in 1787, states “Sun-dew (''Drosera'') derives its name from small drops of a liquor-like dew, hanging on its fringed leaves, and continuing in the hottest part of the day, exposed to the sun.”

Phylogenetics

The unrooted

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

to the right shows the relationship between various subgenera and classes as defined by the analysis of Rivadavia ''et al.'' The monotypic section '' Meristocaulis'' was not included in the study, so its place in this system is unclear. More recent studies have placed this group near section ''Bryastrum'', so it is placed there below. Also of note, the placement of the section ''Regiae'' in relation to ''Aldrovanda'' and ''Dionaea'' is uncertain. Since the section ''Drosera'' is

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

, it shows up multiple times in the cladogram (*). This phylogenetic study has made the need for a revision of the genus even clearer.

Description

Sundews are

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

(or rarely annual)

herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition o ...

s, typically forming prostrate or upright rosettes between in height, depending on the species. Climbing species form scrambling stems which can reach much longer lengths, up to in the case of '' D. erythrogyne''. Sundews have been shown to be able to achieve a lifespan of 50 years. The genus is specialized for

nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

uptake through its carnivorous behavior, for example the pygmy sundew is missing the

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s ( nitrate reductase, in particular) that plants normally use for the uptake of earth-bound nitrates.

Growth form

The genus can be divided into several

habits A habit (or wont, as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously. A 1903 paper in the ''American Journal of Psychology'' defined a "habit, from the standpoint of psychology, hibernaculum in a winter dormancy period (= Hemicryptophyte">hibernaculum (botany)">hibernaculum in a winter dormancy period (= Hemicryptophyte). All of the North American and European species belong to this group. ''Drosera arcturi'' from Australia (including Tasmania) and New Zealand is another temperate species that dies back to a horn-shaped hibernaculum. * Subtropical sundews: These species maintain vegetative growth year-round under uniform or nearly uniform climatic conditions. * Pygmy sundews: A group of roughly 40 Australian species, they are distinguished by miniature growth, the formation of gemmae for asexual reproduction">Gemma (botany)">gemmae for asexual reproduction, and dense formation of hairs in the crown center. These hairs serve to protect the plants from Australia's intense summer sun. Pygmy sundews form the subgenus '' Bryastrum''. * Tuberous sundews: These nearly 50 Australian species form an underground Drosera subg. Bryastrum">Bryastrum''. * Tuberous sundews: These nearly 50 Australian species form an underground tuber to survive the extremely dry summers of their habitat, re-emerging in the autumn. These so-called tuberous sundews can be further divided into two groups, those that form rosettes and those that form climbing or scrambling stems. Tuberous sundews comprise the subgenus '' Ergaleium''. Drosera derbyensis ne1

* ''Petiolaris'' complex: A group of tropical Australian species, they live in constantly warm but sometimes wet conditions. Several of the 14 species that comprise this group have developed special strategies to cope with the alternately drier conditions. Many species, for example, have Petiole (botany)">petioles densely covered in

s, which maintain a sufficiently humid environment and serve as an increased condensation surface for morning dew. The ''Petiolaris'' complex comprises the subgenus ''Drosera subg. Lasiocephala, Lasiocephala''. Although they do not form a single strictly defined growth form, a number of species are often put together in a further group: * Queensland sundews: A small group of three species ('' D. adelae'', '' D. schizandra'' and '' D. prolifera''), all are native to highly humid habitats in the dim understories of the Australian rainforest.

Leaves and carnivory

Sundews are characterised by the glandular tentacles, topped with sticky secretions, that cover their

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

. The trapping and digestion mechanism usually employs two types of glands: stalked glands that secrete sweet mucilage to attract and ensnare insects and enzymes to digest them, and sessile

gland A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

s that absorb the resulting nutrient soup (the latter glands are missing in some species, such as '' D. erythrorhiza''). Small prey, mainly consisting of insects, are attracted by the sweet secretions of the peduncular glands. Upon touching these, the prey become entrapped by sticky mucilage which prevents their progress or escape. Eventually, the prey either succumb to death through exhaustion or through asphyxiation as the mucilage envelops them and clogs their spiracles. Death usually occurs within 15 minutes. The plant meanwhile secretes esterase, peroxidase,

phosphatase In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid Ester, monoester into a phosphate ion and an Alcohol (chemistry), alcohol. Because a phosphatase enzyme catalysis, catalyzes the hydrolysis of its Substrate ...

and

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalysis, catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products ...

enzymes An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as pro ...

. These enzymes dissolve the insect and free the nutrients contained within it. This nutrient mixture is then absorbed through the leaf surfaces to be used by the rest of the plant. Drosera Glandular Hair

All species of sundew are able to move their tentacles in response to contact with edible prey. The tentacles are extremely sensitive and will bend toward the center of the leaf to bring the insect into contact with as many stalked glands as possible. According to

, the contact of the legs of a small gnat with a single tentacle is enough to induce this response. This response to touch is known as

thigmonasty In biology, thigmonasty or seismonasty is the nastic movement, nastic (non-directional) response of a plant or fungus to touch or vibration. Conspicuous examples of thigmonasty include many species in the Fabaceae, leguminous family (biology), su ...

, and is quite rapid in some species. The outer tentacles (recently coined as "snap-tentacles") of '' D. burmanni'' and '' D. sessilifolia'' can bend inwards toward prey in a matter of seconds after contact, while '' D. glanduligera'' is known to bend these tentacles in toward prey in tenths of a second. In addition to tentacle movement, some species are able to bend their leaves to various degrees to maximize contact with the prey. Of these, '' D. capensis'' exhibits what is probably the most dramatic movement, curling its leaf completely around prey in 30 minutes. Some species, such as '' D. filiformis'', are unable to bend their leaves in response to prey. DroseraIndicaEmergences

A further type of (mostly strong red and yellow) leaf coloration has recently been discovered in a few Australian species ('' D. hartmeyerorum'', '' D. indica''). Their function is not known yet, although they may help in attracting prey. The leaf morphology of the species within the genus is extremely varied, ranging from the sessile

ovate Ovate may refer to: * Ovate (egg-shaped) leaves, tepals, or other botanical parts *Ovate, a type of prehistoric stone hand axe * Ovates, one of three ranks of membership in the Welsh Gorsedd * Vates or ovate, a term for ancient Celtic bards ...

leaves of ''D. erythrorhiza'' to the bipinnately divided acicular leaves of '' D. binata''. While the exact physiological mechanism of the sundew's carnivorous response is not yet known, some studies have begun to shed light on how the plant is able to move in response to mechanical and chemical stimulation to envelop and digest prey. Individual tentacles, when mechanically stimulated, fire action potentials that terminate near the base of the tentacle, resulting in rapid movement of the tentacle towards the center of the leaf. This response is more prominent when marginal tentacles further away from the leaf center are stimulated. The tentacle movement response is achieved through auxin-mediated acid growth. When action potentials reach their target cells, the plant hormone

auxin Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essent ...

causes protons (H⁺ ions) to be pumped out of the plasma membrane into the cell wall, thereby reducing the pH and making the cell wall more acidic. The resulting reduction in pH causes the relaxation of the cell wall protein, expansin, and allows for an increase in cell volume via osmosis and turgor. As a result of differential cell growth rates, the sundew tentacles are able to achieve movement towards prey and the leaf center through the bending caused by expanding cells. Among some ''Drosera'' species, a second bending response occurs in which non-local, distant tentacles bend towards prey as well as the bending of the entire leaf blade to maximize contact with prey. While mechanical stimulation is sufficient to achieve a localized tentacle bend response, both mechanical and chemical stimuli are required for the secondary bending response to occur.

Flowers and fruit

The flowers of sundews, as with nearly all carnivorous plants, are held far above the leaves by a long stem. This physical isolation of the flower from the traps is commonly thought to be an adaptation meant to avoid trapping potential

pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...

s. The mostly unforked

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

s are spikes, whose flowers open one at a time and usually only remain open for a short period. Flowers open in response to light intensity (often opening only in direct sunlight), and the entire inflorescence is also heliotropic, moving in response to the sun's position in the sky. Drosera with flower stem

The radially symmetrical ( actinomorphic) flowers are always perfect and have five parts (the exceptions to this rule are the four-petaled '' D. pygmaea'' and the eight to 12-petaled '' D. heterophylla''). Most of the species have small flowers (<1.5 cm or 0.6 in). A few species, however, such as '' D. regia'' and '' D. cistiflora'', have flowers or more in diameter. In general, the flowers are white or pink. Australian species display a wider range of colors, including orange ('' D. callistos''), red ('' D. adelae''), yellow ('' D. zigzagia'') or metallic violet ('' D. microphylla''). The

ovary The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/ oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are end ...

is superior and develops into a

dehiscent Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part. Structures that op ...

seed capsule bearing numerous tiny seeds. The

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

grain type is compound, which means four

microspore Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Megaspo ...

s (pollen grains) are stuck together with a protein called callose.

Roots

The root systems of most ''Drosera'' are often only weakly developed or have lost their original functions. They are relatively useless for nutrient uptake, and they serve mainly to absorb water and to anchor the plant to the ground; they have long

hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and ...

s. A few South African species use their roots for water and food storage. Some species have wiry root systems that remain during frosts if the stem dies. Some species, such as ''D. adelae'' and '' D. hamiltonii'', use their roots for asexual propagation, by sprouting plantlets along their length. Some Australian species form underground

corm Corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen, underground plant stem that serves as a storage organ that some plants use to survive winter or other adverse conditions such as summer drought and heat (perennation). The word ''c ...

s for this purpose, which also serve to allow the plants to survive dry summers. The roots of pygmy sundews are often extremely long in proportion to their size, with a 1-cm (0.4-in) plant extending roots over beneath the soil surface. Some pygmy sundews, such as '' D. lasiantha'' and '' D. scorpioides'', also form adventitious roots as supports. '' D. intermedia'' and '' D. rotundifolia'' have been reported to form arbuscular mycorrhizae, which penetrate the plant's tissues, they also host fungi like

endophyte An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; ...

s to collect nutrients when they grow in poor soil and form symbiotic relationships.

Reproduction

Many species of sundews are self-fertile; their flowers will often self-pollinate upon closing. Often, numerous seeds are produced. The tiny black seeds germinate in response to moisture and light, while seeds of temperate species also require cold, damp, stratification to germinate. Seeds of the tuberous species require a hot, dry summer period followed by a cool, moist winter to germinate.

Vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is a form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or specializ ...

occurs naturally in some species that produce stolons or when roots come close to the surface of the soil. Older leaves that touch the ground may sprout plantlets. Pygmy sundews reproduce asexually using specialized scale-like leaves called gemmae. Tuberous sundews can produce offsets from their corms. In culture, sundews can often be propagated through leaf, crown, or root cuttings, as well as through seeds.

Distribution

The range of the sundew genus stretches from Alaska in the north to New Zealand in the south. The centers of

diversity Diversity, diversify, or diverse may refer to: Business *Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce *Diversity marketing, marketing communication targeting diverse customers * ...

are Australia, with roughly 50% of all known species, and South America and southern Africa, each with more than 20 species. A few species are also found in large parts of Eurasia and North America. These areas, however, can be considered to form the outskirts of the generic range, as the ranges of sundews do not typically approach temperate or Arctic areas. Contrary to previous supposition, the evolutionary

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

of this genus is no longer thought to have occurred with the breakup of

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

through

continental drift Continental drift is a highly supported scientific theory, originating in the early 20th century, that Earth's continents move or drift relative to each other over geologic time. The theory of continental drift has since been validated and inc ...

. Rather, speciation is now thought to have occurred as a result of a subsequent wide dispersal of its range. The origins of the genus are thought to have been in Africa or Australia. Europe is home to only three species: '' D. intermedia'', '' D. anglica'', and '' D. rotundifolia''. Where the ranges of the two latter species overlap, they sometimes hybridize to form the sterile '' D. × obovata''. In addition to the three species and the hybrid native to Europe, North America is also home to four additional species; '' D. brevifolia'' is a small annual native to coastal states from

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

, while '' D. capillaris'', a slightly larger plant with a similar range, is also found in areas of the Caribbean. The third species, '' D. linearis'', is native to the northern United States and southern Canada. '' D. filiformis'' has two

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

native to the East Coast of North America, the Gulf Coast, and the

Florida panhandle The Florida panhandle (also known as West Florida and Northwest Florida) is the northwestern part of the U.S. state of Florida. It is a Salient (geography), salient roughly long, bordered by Alabama on the west and north, Georgia (U.S. state ...

. This genus is often described as

cosmopolitan Cosmopolitan may refer to: Internationalism * World citizen, one who eschews traditional geopolitical divisions derived from national citizenship * Cosmopolitanism, the idea that all of humanity belongs to a single moral community * Cosmopolitan ...

, meaning it has worldwide distribution. The botanist

Ludwig Diels Friedrich Ludwig Emil Diels (24 September 1874 – 30 November 1945) was a German botanist. Diels was born in Hamburg, the son of the classical scholar Hermann Alexander Diels. From 1900 to 1902 he traveled together with Ernst Georg Pritzel thro ...

, author of the only

monograph A monograph is generally a long-form work on one (usually scholarly) subject, or one aspect of a subject, typically created by a single author or artist (or, sometimes, by two or more authors). Traditionally it is in written form and published a ...

of the family to date, called this description an "arrant misjudgment of this genus' highly unusual distributional circumstances (''arge Verkennung ihrer höchst eigentümlichen Verbreitungsverhältnisse'')", while admitting sundew species do "occupy a significant part of the Earth's surface (''einen beträchtlichen Teil der Erdoberfläche besetzt'')". He particularly pointed to the absence of ''Drosera'' species from almost all

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

climate zones, countless

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

s, the American Pacific Coast,

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

, the Mediterranean region, and North Africa, as well as the scarcity of species diversity in temperate zones, such as Europe and North America.

Habitat

Sundews generally grow in seasonally moist or more rarely constantly wet habitats with acidic soils and high levels of sunlight. Common habitats include

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 musk ...

s, fens,

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

es, the tepuis of Venezuela, the wallums of coastal Australia, the

fynbos Fynbos (; , ) is a small belt of natural shrubland or heathland vegetation located in the Western Cape and Eastern Cape provinces of South Africa. The area is predominantly coastal and mountainous, with a Mediterranean climate. The fynbos ...

of South Africa, and moist streambanks. Many species grow in association with

sphagnum moss ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store water, since ...

, which absorbs much of the soil's nutrient supply and also acidifies the soil, making nutrients less available to plant life. This allows sundews, which do not rely on soil-bound nutrients, to flourish where more dominating vegetation would usually outcompete them. The genus, though, is very variable in terms of habitat. Individual sundew species have adapted to a wide variety of environments, including atypical habitats, such as rainforests, deserts ('' D. burmanni'' and '' D. indica''), and even highly shaded environments (Queensland sundews). The temperate species, which form hibernacula in the winter, are examples of such adaptation to habitats; in general, sundews tend to inhabit warm climates, and are only moderately frost-resistant.

Conservation status

Protection of the genus varies between countries. None of the ''Drosera'' species in the United States are federally protected. Some are listed as threatened or

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

at the state level, but this gives little protection to lands under private ownership. Many of the remaining native populations are located on protected land, such as

national park A national park is a nature park designated for conservation (ethic), conservation purposes because of unparalleled national natural, historic, or cultural significance. It is an area of natural, semi-natural, or developed land that is protecte ...

s or wildlife preserves. ''Drosera'' species are protected by law in many European countries, such as Germany, Austria, Switzerland, the Czech Republic, Finland,

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

, and Bulgaria. In Australia, they are listed as "threatened". In South America and the Caribbean, ''Drosera'' species in a number of areas are considered critical, endangered or vulnerable, while other areas have not been surveyed. At the same time that species are at risk in South Africa, new species continue to be discovered in the

Western Cape The Western Cape ( ; , ) is a provinces of South Africa, province of South Africa, situated on the south-western coast of the country. It is the List of South African provinces by area, fourth largest of the nine provinces with an area of , an ...

and

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. Worldwide, ''Drosera'' are at risk of extinction due to the destruction of natural habitat through urban and agricultural development. They are also threatened by the illegal collection of wild plants for the horticultural trade. An additional risk is

environmental change Environment most often refers to: __NOTOC__ * Natural environment, referring respectively to all living and non-living things occurring naturally and the physical and biological factors along with their chemical interactions that affect an organism ...

, because species are often specifically adapted to a precise location and set of conditions. Currently, the largest threat in Europe and North America is loss of wetland habitat. Causes include urban development and the draining of bogs for agricultural uses and peat harvesting. Such threats have led to the extirpation of some species from parts of their former range. Reintroduction of plants into such habitats is usually difficult or impossible, as the ecological needs of certain populations are closely tied to their geographical location. Increased legal protection of bogs and moors, and a concentrated effort to renaturalize such habitats, are possible ways to combat threats to ''Drosera'' plants' survival. As part of the landscape, sundews are often overlooked or not recognized at all. In South Africa and Australia, two of the three centers of species diversity, the natural habitats of these plants are undergoing a high degree of pressure from human activities. The African sundews '' D. insolita'' and '' D. katangensis'' are listed as critically endangered by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

(IUCN), while '' D. bequaertii'' is listed as vulnerable. Expanding population centers such as

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

Perth Perth () is the list of Australian capital cities, capital city of Western Australia. It is the list of cities in Australia by population, fourth-most-populous city in Australia, with a population of over 2.3 million within Greater Perth . The ...

, and

Cape Town Cape Town is the legislature, legislative capital city, capital of South Africa. It is the country's oldest city and the seat of the Parliament of South Africa. Cape Town is the country's List of municipalities in South Africa, second-largest ...

, and the draining of moist areas for agriculture and forestry in rural areas threaten many such habitats. The droughts that have been sweeping Australia in the 21st century pose a threat to many species by drying up previously moist areas. Those species endemic to a very limited area are often most threatened by the collection of plants from the wild. '' D. madagascariensis'' is considered endangered in

because of the large-scale removal of plants from the wild for exportation; 10 - 200 million plants are harvested for commercial medicinal use annually.

Gallery of prey

File:Drosera. Tipulidae.jpg, Tipulidae (crane fly) trapped by ''Drosera filiformis'' File:Drosera. Phalaenophana.jpg, Moth, ''Phalaenophana pyramusalis'' (Dark-banded Owlet) trapped by ''Drosera filiformis'' File:Drosera. Eusarca confusaria.jpg, ''Eusarca confusaria'' moth trapped by ''Drosera filiformis'' File:Drosera. Tabanus ventral.jpg, ''Tabanus'' fly trapped by ''Drosera filiformis'' File:Drosophila melanogaster ♀ Melgen, 1830, Drosera capensis Linnaeus, 1753 1100.1.2171.JPG, ''Drosophila melanogaster'' fly trapped by ''Drosera capensis''

Uses

The

s of the tuberous sundews native to Australia are considered a delicacy by the

Indigenous Australians Indigenous Australians are people with familial heritage from, or recognised membership of, the various ethnic groups living within the territory of contemporary Australia prior to History of Australia (1788–1850), British colonisation. The ...

. Some of these corms were also used to dye textiles,Plantarara (2001)
Artzneimittle, Tee, und Likör aus fleischfressenden Pflanzen
while another purple or yellow dye was traditionally prepared in the

Scottish Highlands The Highlands (; , ) is a historical region of Scotland. Culturally, the Highlands and the Scottish Lowlands, Lowlands diverged from the Late Middle Ages into the modern period, when Scots language, Lowland Scots language replaced Scottish Gae ...

using ''D. rotundifolia''. A sundew

liqueur A liqueur ( , ; ) is an alcoholic drink composed of Liquor, spirits (often rectified spirit) and additional flavorings such as sugar, fruits, herbs, and spices. Often served with or after dessert, they are typically heavily sweetened and un-age ...

is made using fresh leaves from mainly '' D. capensis'', '' D. spatulata'', and ''D. rotundifolia''.

Traditional medicine

The Zafimaniry people in central Madagascar have been using '' Drosera madagascariensis'' as a remedy for dysentery and fever. In Western medicine, sundews were used as medicinal herbs as early as the 12th century, when an Italian doctor from the School of Salerno, Matthaeus Platearius, described the plant as an herbal remedy for

cough A cough is a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles and Microorganism, microbes. As a protective reflex, coughing can be repetitive with the cough reflex fol ...

s under the name ''herba sole''. Culbreth's 1927 ''Materia Medica'' listed ''D. rotundifolia'', ''D. anglica'' and '' D. linearis'' as being used as

stimulants Stimulants (also known as central nervous system stimulants, or psychostimulants, or colloquially as uppers) are a class of drugs that increase alertness. They are used for various purposes, such as enhancing attention, motivation, cognitio ...

and expectorants, and "of doubtful efficacy" for treating

bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...

whooping cough Whooping cough ( or ), also known as pertussis or the 100-day cough, is a highly contagious, Vaccine-preventable diseases, vaccine-preventable Pathogenic bacteria, bacterial disease. Initial symptoms are usually similar to those of the common c ...

, and

tuberculosis Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...

. Sundew tea was recommended by herbalists for dry coughs,

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

and "bronchial cramps". The ''French Pharmacopoeia'' of 1965 listed sundew for the treatment of inflammatory diseases such as asthma,

chronic bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...

and whooping cough. ''Drosera'' has been used commonly in cough preparations in Germany and elsewhere in Europe. In

traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) refers to the knowledge, skills, and practices rooted in the cultural beliefs of various societies, especially Indigenous groups, used for maintaining health and treatin ...

practices, ''Drosera'' is used to treat ailments such as

, coughs, lung infections, and stomach ulcers. Herbal preparations are primarily made using the roots, flowers, and fruit-like capsules. Since all native sundews species are protected in many parts of Europe and North America,

extract An extract (essence) is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol, oil or water. Extracts may be sold as tinctures or absolutes or dried and powdered. The aromatic principles of ma ...

s are usually prepared using cultivated fast-growing sundews (specifically ''D. rotundifolia'', '' D. intermedia'', ''D. anglica'', '' D. ramentacea'' and ''D. madagascariensis'') or from plants collected and imported from Madagascar, Spain, France, Finland and the

Baltics The Baltic states or the Baltic countries is a geopolitical term encompassing Estonia, Latvia, and Lithuania. All three countries are members of NATO, the European Union, the Eurozone, and the OECD. The three sovereign states on the eastern co ...

. Sundews are historically mentioned as an

aphrodisiac An aphrodisiac is a substance that increases libido, sexual desire, sexual attraction, sexual pleasure, or sexual behavior. These substances range from a variety of plants, spices, and foods to synthetic chemicals. Natural aphrodisiacs, such as ...

(hence the common name ''lustwort''). They are mentioned as a folk remedy for treatment of warts, corns, and freckles.

As ornamental plants

Because of their carnivorous nature and the beauty of their glistening traps, sundews have become favorite

ornamental plant Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

s; however, the environmental requirements of most species are relatively stringent and can be difficult to meet in cultivation. As a result, most species are unavailable commercially. A few of the hardiest varieties, however, have made their way into the mainstream nursery business and can often be found for sale next to Venus flytraps. These most often include '' D. capensis'', '' D. aliciae'', and '' D. spatulata''.Rice, Barry. 2006. ''Growing Carnivorous Plants''. Timber Press: Portland, Oregon. Cultivation requirements vary greatly by species. In general, though, sundews require high environmental moisture content, usually in the form of a constantly moist or wet soil substrate. Most species also require this water to be pure, as nutrients, salts, or minerals in their soil can stunt their growth or even kill them. Commonly, plants are grown in a soil substrate containing some combination of dead or live

sphagnum ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store water, since ...

peat moss, sand, and/or

perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the Hydrate, hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an indu ...

, and are watered with

distilled Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixt ...

reverse osmosis Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane, semi-permeable membrane to separate water molecules from other substances. RO applies pressure to overcome osmotic pressure that favors even distribu ...

, or rain water.

Nano-biotechnology

The mucilage produced by ''Drosera'' has remarkable elastic properties and has made this genus a very attractive subject in biomaterials research. In one recent study, the adhesive mucilages of three species (''D. binata'', ''D. capensis'', and ''D. spatulata'') were analyzed for nanofiber and

nanoparticle A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...

content. Using atomic force microscopy,

transmission electron microscopy Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a g ...

, and energy-dispersive X-ray spectroscopy, researchers were able to observe networks of nanofibers and nanoparticles of various sizes within the mucilage residues. In addition,

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

, and

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

– key components of biological salts - were identified. These nanoparticles are theorized to increase the viscosity and stickiness of the mucilage, in turn increasing the effectiveness of the trap. More importantly for biomaterials research, however, is the fact that, when dried, the mucilage provides a suitable substrate for the attachment of living cells. This has important implications for tissue engineering, especially because of the elastic qualities of the adhesive. Essentially, a coating of ''Drosera'' mucilage on a surgical implant, such as a replacement hip or an organ transplant, could drastically improve the rate of recovery and decrease the potential for rejection, because living tissue can effectively attach and grow on it. The authors also suggest a wide variety of applications for ''Drosera'' mucilage, including wound treatment, regenerative medicine, or enhancing synthetic adhesives. Because this mucilage can stretch to nearly a million times its original size and is readily available for use, it can be an extremely cost-efficient source of biomaterial.

Chemical constituents

Several chemical compounds with potential biological activities are found in sundews, including

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s (

kaempferol Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. It is also found in propolis extracts. Kaempferol i ...

myricetin Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is stru ...

, quercetin and hyperoside), quinones ( plumbagin, hydroplumbagin glucoside and rossoliside (7–methyl–hydrojuglone–4–glucoside)), and other constituents such as

carotenoid Carotenoids () are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, cana ...

s, plant acids (e.g.

butyric acid Butyric acid (; from , meaning "butter"), also known under the systematic name butanoic acid, is a straight-chain alkyl carboxylic acid with the chemical formula . It is an oily, colorless liquid with an unpleasant odor. Isobutyric acid (2-met ...

citric acid Citric acid is an organic compound with the formula . It is a Transparency and translucency, colorless Weak acid, weak organic acid. It occurs naturally in Citrus, citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, ...

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid. It has the chemical formula HCOOH and structure . This acid is an important intermediate in chemical synthesis and occurs naturally, most notably in some an ...

, gallic acid,

malic acid Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ( ...

propionic acid Propionic acid (, from the Greek language, Greek words πρῶτος : ''prōtos'', meaning "first", and πίων : ''píōn'', meaning "fat"; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula . It is a ...

resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...

, tannins and

ascorbic acid Ascorbic acid is an organic compound with formula , originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves freely in water to give mildly acidic solutions. It is a mild reducing agent. Asco ...

(vitamin C).

References

External links

A key to ''Drosera'' species, with distribution maps and growing difficulty scale

* ttp://www.carnivorousplants.org/ International Carnivorous Plant Society
Carnivorous Plant FAQ

The Sundew Grow Guides

Sundew images from smugmug

Botanical Society of America, ''Drosera'' - the Sundews
{{Taxonbar, from=Q266 Taxa named by Carl Linnaeus

Taxonomy

Phylogenetics

Description

Growth form

Leaves and carnivory

Flowers and fruit

Roots

Reproduction

Distribution

Habitat

Conservation status

Gallery of prey

Uses

Traditional medicine

As ornamental plants

Nano-biotechnology

Chemical constituents

References

Further reading

External links