Droseraceae

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Droseraceae
Temporal range: Late Cretaceous–Recent
Drosera rotundifolia habitat.jpg
Drosera rotundifolia in habitat in Oregon
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Droseraceae
Salisb. [1]
Genera

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 well-known Venus flytrap (Dionaea muscipula) and the more obscure waterwheel plant (Aldrovanda vesiculosa), both of which are the only living species of their respective genera. [2] Representatives of the Droseraceae are found on all continents except Antarctica.

Contents

Description

Droseraceae are carnivorous herbaceous plants that may be annuals or perennials. Their leaves are alternate and adaxially circinate, with at least one leaf surface containing hairs with mucilage-producing glands at the tip. Their flowers are bisexual, usually with three carpels and five sepals, petals and stamens.  Their pollen grains are triporate or multiporate and released in tetrads. Despite being carnivorous, their flowers are insect-pollinated, typically with white to purple flowers that close at night. They produce small seeds that are dispersed by wind and water. [3]

Most of the members of Droseraceae are contained in the genus Drosera , the sundews. Both Dionaea and Aldrovanda have only one extant species. Drosera species trap prey by secreting a sticky substance from hairs on their leaves. Dionaea and Aldrovanda both use snap-traps that close rapidly when the leaves are disturbed. Dionaea is terrestrial, while Aldrovanda is strictly aquatic. Like carnivorous plants of other families, the Droseraceae are able to supplement their nutrient intake, especially that of nitrogen, by capturing and digesting small animals such as insects. In this way, these plants are able to thrive in nutrient-deficient areas, such as sphagnum bogs.

Drosera

Drosera is one of the largest genera of carnivorous plants, and individual species vary extensively in their specific morphology. Common to all members of Drosera are highly modified leaves lined with tentacle-like glandular trichomes. At the end of each trichome, a bead of highly viscous mucilage is secreted, which resembles a drop of dew. The mucilage is a fairly pure aqueous solution of acidic polysaccharides with high molecular weights, which makes the mucilage not only highly viscous, but also very sticky, [4] so much so, a single drop of mucilage may be stretched to lengths of up to a meter and cover one million times its original surface area. [4] [5] Insects and other prey animals are attracted by the smell of this mucilage and become stuck in it. Such snares are termed "flypaper traps", but the trapping mechanism of sundews is often erroneously described as "passive". In fact, sundew traps are quite active and sensitive, and the disturbance of one or a few trichomes quickly triggers an action potential that stimulates the rapid movement of other trichomes toward the prey. The leaf then curls in on itself, enveloping the prey for digestion. [6]

Four Drosera subgenera are recognized today: subgenus Regiae and subgenus Arcturia are each monotypic (D. regia and D. arcturi, respectively), and the remaining Drosera are divided into two clades, subgenus Ergaleium and subgenus Drosera. [7]

Dionaea

Dionaea muscipula , better known as the Venus flytrap, is a globally famous carnivorous plant and according to Charles Darwin, "one of the most wonderful in the world." [8] The leaves of Dionaea are also highly modified and form a "snap-trap" that quickly shuts when a stimulus is detected. Three large trichomes extend outward on the inner surface of the trap. Two of these three hairs must be stimulated within a certain amount of time to trigger the trap. The trap closes as the result of a flipping of the trap lobes from a position where the exterior of the trap is concave to one where the exterior is convex. This movement can begin as soon as 0.4 seconds after stimulation and can be completed after one second. [6]

Aldrovanda

Aldrovanda vesiculosa , also called the waterwheel plant, is a free-floating, rootless, aquatic plant. [9] It is less well-known than its relative Dionaea muscipula, but the two have similar trap structures. In 1875, Darwin described Aldrovanda as "a miniature aquatic Dionaea". [8] The trap of Aldrovanda is aquatic and is smaller and faster than that of Dionaea. [6] In addition, while two stimuli are required to close a trap in Dionaea, only one is required in Aldrovanda. The trap of Aldrovanda closes about ten times faster than that of Dionaea. [6]

Etymology

The type genus for the Droseraceae is Drosera, which was described and named by Linnaeus in 1753.  The name was derived from the Greek word "droseros", meaning "dewy" or "drops of water".  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." [10]

Phylogeny

In 1867, Bentham and Hooker placed six genera in the Droseraceae: Dionaea, Aldrovanda, Drosera, Drosophyllum, Byblis, and Roridula. [11]   Although these genera had significant differences in leaf and flower morphologies, they were grouped together on the basis of insect traps that appeared to be homologous. [12] In 1922, Byblis and Roridula were moved into a new family, the Byblidaceae (and later further split out, forming the Roridulaceae). [12] In the 1990s, both morphological and molecular evidence began to build that Drosophyllum differed from the other genera in the Droseraceae, [13] Drosophyllum, another monotypic genus ( Drosophyllum lusitanicum being the only species), exhibits a flypaper-type trap similar to those of Drosera, but Drosophyllum does not actively curl its leaves to envelop captured prey animals. This important morphological distinction led researchers to question the validity of this taxon's placement in Droseraceae. Other significant trait differences in Drosophyllum include pollen structure, trichome anatomy, and a woody stem with a deep taproot. [13] Ultimately, Drosophyllum was shown to be more closely related to the carnivorous liana Triphyophyllum and the noncarnivorous liana Ancistrocladus , and is, thus, classified elsewhere (to be specific, its own monotypic family Drosophyllaceae). [14] and APG III (2009) placed it into its own family, the Drosophyllaceae. [12]   This left only the three genera (Dionaea, Aldrovanda, Drosera) that are classified as Droseraceae today.

Despite some debate, taxonomists have tended to include at least two of these three genera, and, in general, all three, in this family since at least 1906. [14] Separate families for Dionaea and Aldrovanda have been proposed in the past. These were Dionaecae, proposed in 1933, and Aldrovandaceae, proposed in 1949. [13] Ultimately, molecular and morphological evidence support the inclusion of all three, confirming that the Droseraceae are a monophyletic group. [14] Molecular evidence also shows that the two genera with traps that snap shut (Dionaea and Aldrovanda) are more closely related to each other than to Drosera, suggesting snap traps evolved only once. [14]

The family Droseraceae is part of the order Caryophyllales in the Superasterid clade within the core eudicots. [14] [3] The family totals nearly 200 species. Caryophyllales are divided into two major suborders: Caryophyllineae, which contains the "core" Caryophyllales, such as Cactaceae and Amaranthaceae and is sister to the Polygonineae – the "non-core" Caryophyllales. This non-core clade is where Droseraceae is placed. [15]

Recent molecular and biochemical evidence [16] suggests the carnivorous taxa in the order Caryophyllales (the families Droseraceae, Drosophyllaceae, Nepenthaceae, and the species Triphyophyllum peltatum ) all belong to the same clade, which does not consist only of carnivorous plants, but also of some noncarnivorous plants such as those in the family Ancistrocladaceae.

The fossil record of Droseraceae is the richest of any carnivorous plant family. Fossil pollen has been attributed to several extant, as well as extinct, genera, although some are of questionable validity.

Evolution

Darwin concluded that carnivory in plants was convergent, writing in 1875 that Utricularia and Nepenthes were not "at all related to the Droseraceae". [8] This remained a subject of debate for over a century. In 1960, Leon Croizat concluded that carnivory was monophyletic, and placed all the carnivorous plants together at the base of the angiosperms. [11]   Molecular studies over the past 30 years have led to a wide consensus that Darwin was correct, with studies showing that carnivory evolved at least six times in the angiosperms, and that trap designs such as pitcher traps and flypaper traps are analogous rather than homologous. [17]  

The origin of carnivory within the ancestors of the Droseraceae has been dated to 85.6 million years ago, with the evolution of snap-traps dated to 48 million years ago. [12] Researchers have hypothesized that carnivory in the Droseraceae began with simple flypaper traps, followed by movement of tentacles in some Drosera-like species, followed by movement of leaves, leading eventually to the development of snap-traps in Dionaea and Aldrovanda by increasing the speed of the leaf movements and altering the morphology of the leaves. [18]   [19] Due to the sister relationship of Dionaea and Aldrovanda, it is likely that the snap-trap mechanism only evolved once, but it is unknown if the common ancestor was terrestrial or aquatic. [20]

Related Research Articles

<i>Drosera</i> Genus of carnivorous flowering plants in the family Droseraceae

Drosera, which is commonly known as the sundews, is one of the largest genera of carnivorous plants, with at least 194 species. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginous 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.

<span class="mw-page-title-main">Venus flytrap</span> Species of carnivorous plant

The Venus flytrap is a carnivorous plant native to the temperate and subtropical wetlands of North Carolina and South Carolina, on the East Coast of the United States. Although various modern hybrids have been created in cultivation, D. muscipula is the only species of the monotypic genus Dionaea. It is closely related to the waterwheel plant and the cosmopolitan sundews (Drosera), all of which belong to the family Droseraceae. Dionaea catches its prey—chiefly insects and arachnids—with a "jaw"-like clamping structure, which is formed by the terminal portion of each of the plant's leaves; when an insect makes contact with the open leaves, vibrations from the prey's movements ultimately trigger the "jaws" to shut via tiny hairs on their inner surfaces. Additionally, when an insect or spider touches one of these hairs, the trap prepares to close, only fully enclosing the prey if a second hair is contacted within (approximately) twenty seconds of the first contact. Triggers may occur as quickly as 1⁄10 of a second from initial contact.

<span class="mw-page-title-main">Lentibulariaceae</span> Family of carnivorous plants

Lentibulariaceae is a family of carnivorous plants containing three genera: Genlisea, the corkscrew plants; Pinguicula, the butterworts; and Utricularia, the bladderworts.

<i>Drosophyllum</i> Genus of carnivorous plants

Drosophyllum is a genus of carnivorous plants containing the single species Drosophyllum lusitanicum, commonly known as Portuguese sundew or dewy pine. In appearance, it is similar to the related genus Drosera, and to the much more distantly related Byblis.

<i>Aldrovanda vesiculosa</i> Species of plant (waterwheel plant)

Aldrovanda vesiculosa, commonly known as the waterwheel plant, is the sole extant species in the flowering plant genus Aldrovanda of the family Droseraceae. The plant captures small aquatic invertebrates using traps similar to those of the Venus flytrap. The traps are arranged in whorls around a central, free-floating stem, giving rise to the common name. This is one of the few plant species capable of rapid movement.

<i>Byblis</i> (plant) Genus of carnivorous plants

Byblis is a small genus of carnivorous plants, sometimes termed the rainbow plants for the attractive appearance of their mucilage-covered leaves in bright sunshine. Native to Australia and New Guinea, it is the only genus in the family Byblidaceae. The first species in the genus was described by the English botanist Richard Anthony Salisbury in 1808. Eight species are now recognised.

<i>Drosera capillaris</i> Species of carnivorous plant native to subtropical to tropical North and South America

Drosera capillaris, also known as the pink sundew, is a species of carnivorous plant belonging to the family Droseraceae. It is native to the southern United States, the Greater Antilles, western and southern Mexico, Central America, and northern South America. It is listed as vulnerable in the US state of Virginia, and critically imperiled in Arkansas, Maryland, and Tennessee.

<span class="mw-page-title-main">Rapid plant movement</span> Short period movement of plants

Rapid plant movement encompasses movement in plant structures occurring over a very short period, usually under one second. For example, the Venus flytrap closes its trap in about 100 milliseconds. The traps of Utricularia are much faster, closing in about 0.5 milliseconds. The dogwood bunchberry's flower opens its petals and fires pollen in less than 0.5 milliseconds. The record is currently held by the white mulberry tree, with flower movement taking 25 microseconds, as pollen is catapulted from the stamens at velocities in excess of half the speed of sound—near the theoretical physical limits for movements in plants.

<i>Drosera rotundifolia</i> Species of flowering plant in the sundew family Droseraceae

Drosera rotundifolia, the round-leaved sundew, roundleaf sundew, or common sundew, is a carnivorous species of flowering plant that grows in bogs, marshes and fens. One of the most widespread sundew species, it has a circumboreal distribution, being found in all of northern Europe, much of Siberia, large parts of northern North America, Korea and Japan but is also found as far south as California, Mississippi and Alabama in the United States of America and in New Guinea.

<i>Drosera regia</i> Species of carnivorous plant in the family Droseraceaea endemic to a single valley in South Africa

Drosera regia, commonly known as the king sundew, is a carnivorous plant in the sundew genus Drosera that is endemic to a single valley in South Africa. The genus name Drosera comes from the Greek word droseros, meaning "dew-covered". The specific epithet regia is derived from the Latin for "royal", a reference to the "striking appearance" of the species. Individual leaves can reach 70 cm (28 in) in length. It has many unusual relict characteristics not found in most other Drosera species, including woody rhizomes, operculate pollen, and the lack of circinate vernation in scape growth. All of these factors, combined with molecular data from phylogenetic analysis, contribute to the evidence that D. regia possesses some of the most ancient characteristics within the genus. Some of these are shared with the related Venus flytrap (Dionaea muscipula), which suggests a close evolutionary relationship.

<i>Aldrovanda</i> Genus of carnivorous plants

Aldrovanda is a genus of carnivorous plants encompassing one extant species and numerous extinct taxa. The genus is named in honor of the Italian naturalist Ulisse Aldrovandi, the founder of the Botanical Garden of Bologna, Orto Botanico dell'Università di Bologna. Aldrovanda vesiculosa has been reported from scattered locations in Europe, Asia, Africa, and Australia.

<i>Drosera anglica</i> Species of carnivorous flowering plant in the family Droseraceae

Drosera anglica, commonly known as the English sundew or great sundew, is a carnivorous flowering plant species belonging to the sundew family Droseraceae. It is a temperate species with a circumboreal range, although it does occur as far south as Japan, southern Europe, and the island of Kauai in Hawaii, where it grows as a tropical sundew. It is thought to originate from an amphidiploid hybrid of D. rotundifolia and D. linearis, meaning that a sterile hybrid between these two species doubled its chromosomes to produce fertile progeny which stabilized into the current D. anglica.

<span class="mw-page-title-main">Protocarnivorous plant</span> Carnivorous plant that can not digest prey

A protocarnivorous plant, according to some definitions, traps and kills insects or other animals but lacks the ability to either directly digest or absorb nutrients from its prey like a carnivorous plant. The morphological adaptations such as sticky trichomes or pitfall traps of protocarnivorous plants parallel the trap structures of confirmed carnivorous plants.

<span class="mw-page-title-main">Caryophyllales</span> Order of flowering plants

Caryophyllales is a diverse and heterogeneous order of flowering plants that includes the cacti, carnations, amaranths, ice plants, beets, and many carnivorous plants. Many members are succulent, having fleshy stems or leaves. The betalain pigments are unique in plants of this order and occur in all its families with the exception of Caryophyllaceae and Molluginaceae.

<span class="mw-page-title-main">Carnivorous plant</span> Plants that consume animals

Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods, and occasionally small mammals and birds. They still generate all of their energy from photosynthesis. They have adapted to grow in waterlogged sunny places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs. They can be found on all continents except Antarctica, as well as many Pacific islands. In 1875, Charles Darwin published Insectivorous Plants, the first treatise to recognize the significance of carnivory in plants, describing years of painstaking research.

<i>Drosera uniflora</i> Species of carnivorous plant

Drosera uniflora is a species in the carnivorous plant genus Drosera that is native to southern Chile, Argentina, and the Falkland Islands. It is a tiny sundew with a solitary white flower as its name would suggest. Stalked glands on its leaves, which secrete sticky mucilage at the tips, are used to capture and hold insect prey, from which the plant derives the nutrients it cannot obtain in sufficient quantity from the soil. It was formally described in 1809 by botanist Carl Ludwig Willdenow.

<i>Drosera falconeri</i> Species of carnivorous plant

Drosera falconeri is a carnivorous plant in the family of Droseraceae. It is endemic to the Northern Territory of Australia.

Drosera peruensis is a carnivorous plant of the genus Drosera, commonly known as the Peruvian sundew. This Drosera species was first identified in Peru in 2002 by Tânia Regina dos Santos Silva and Mireya D. Correa following work to update the genus Drosera for the reference text, Flora Neotropica..

<i>Drosera kaieteurensis</i> Species of carnivorous plant

Drosera kaieteurensis is a plant from the sundew family (Droseraceae).

<span class="mw-page-title-main">Steel trap (carnivorous plants)</span> Prey capture device of some carnivorous plants

Steel trap is an informal term in the study of comparative plant physiology of the carnivorous plants. "Steel trap", more particularly "active steel trap", refers to prey capture devices such as occur in some members of the family Droseraceae, and in particular in the genera Dionaea and Aldrovanda ("waterwheel"). The term apparently originated with the author Francis Ernest Lloyd in 1942, in which he adopted the overly general term "steel trap" rather than say, "gin trap" or a more adjectival form, for devices such as the lobed trap leaves of Dionaea.

References

  1. ↑ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi: 10.1111/j.1095-8339.2009.00996.x . hdl: 10654/18083 .
  2. ↑ Christenhusz, M. J. M. & Byng, J. W. (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. 261 (3). Magnolia Press: 201–217. doi: 10.11646/phytotaxa.261.3.1 .
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  4. 1 2 Rost, K.; Schauer, R. (1977), "Physical and chemical properties of the mucilage secreted by Drosera capensis", Phytochemistry, 16 (9): 1635–1638, doi:10.1016/s0031-9422(00)88783-x
  5. ↑ Zhang, M.; Lenaghan, S.C.; Xia, L.; Dong, L.; He, W.; Henson, W.R.; Fan, X. (2010), "Nanofibers and nanoparticles from the insect capturing adhesive of the Sundew (Drosera) for cell attachment", Journal of Nanobiotechnology, 8 (20): 20, doi: 10.1186/1477-3155-8-20 , PMC   2931452 , PMID   20718990
  6. 1 2 3 4 Williams, S.E. (2002), "Comparative physiology of the Droseraceae sensu stricto – How do tentacles bend and traps close?", Proceedings of the 4th International Carnivorous Plant Conference: 77–81
  7. ↑ Fleischmann, A.; Cross, Adam; Gibson, R.; Gonella, P.; Dixon, Kingsley (2018), "Systematics and evolution of droseraceae", Carnivorous Plants: Physiology, Ecology, and Evolution, pp. 45–57, ISBN   978-0-19-877984-1 , retrieved 13 December 2019
  8. 1 2 3 Darwin, C. (1875), Insectivorous Plants, London, UK: John Murray
  9. ↑ Cross, A. (2012). "Aldrovanda vesiculosa, Waterwheel". IUCN Red List. Retrieved 13 December 2019.
  10. ↑ Linné, Carl von (1787). "Principia Botanica", Or a Concise and Easy Introduction to the Sexual Botany of Linnaeus, with the "genera", Their Mode of Growth ... the Number of "species" to Each "genus", where Principally Native and the Number Indigenous to the British Isles ... Together with Three Indexes: I. of the Linnaean "genera" Accented, with the British Names ; II. of Such Trivial Names as Were the "genera" of Old Authors ; III. of the British Names, with the Linnaean "genera", to which are Added Many of the Specific Names, Also, a Table of Several Vegetable Drugs Not in the Indexes ... G.G.J. and J. Robinson.
  11. 1 2 Ellison, Aaron M.; Gotelli, Nicholas J. (1 January 2009). "Energetics and the evolution of carnivorous plants—Darwin's 'most wonderful plants in the world'". Journal of Experimental Botany. 60 (1): 19–42. doi: 10.1093/jxb/ern179 . ISSN   0022-0957. PMID   19213724.
  12. 1 2 3 4 Ellison, Aaron M.; Adamec, Lubomír (2018). Carnivorous Plants: Physiology, Ecology, and Evolution. Oxford University Press. ISBN   978-0-19-877984-1.
  13. 1 2 3 Williams, S.E.; Albert, V.A.; Chase, M.W. (1994), "Relationships of Droseraceae: a cladistic analysis of rbcL sequence and morphological data", American Journal of Botany, 81 (8): 1027–1037, doi:10.2307/2445297, JSTOR   2445297
  14. 1 2 3 4 5 Cameron, K. M.; Wurdack, K. J.; Jobson, R. W. (2002), "Molecular evidence for the common origin of snap-traps among carnivorous plants", American Journal of Botany, 89 (9): 1503–9, doi:10.3732/ajb.89.9.1503, PMID   21665752
  15. ↑ Cuénoud, P.; Savolainen, V.; Chatrou, L.W.; Powell, M.; Grayer, R.J.; Chase, M.W. (2002), "Molecular phylogenetics of Caryophyllales based on nuclear 18S rDNA and plastid rbcL, atpB, and matK DNA sequences", American Journal of Botany, 89 (1): 132–144, doi:10.3732/ajb.89.1.132, PMID   21669721
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  19. ↑ Poppinga, Simon; Hartmeyer, Siegfried R. H.; Masselter, Tom; Hartmeyer, Irmgard; Speck, Thomas (1 July 2013). "Trap diversity and evolution in the family Droseraceae". Plant Signaling & Behavior. 8 (7): e24685. Bibcode:2013PlSiB...8E4685P. doi:10.4161/psb.24685. PMC   3907454 . PMID   23603942.
  20. ↑ Rivadavia, Fernando; Kondo, Katsuhiko; Kato, Masahiro; Hasebe, Mitsuyasu (2003). "Phylogeny of the sundews, Drosera (Droseraceae), based on chloroplast rbcL and nuclear 18S ribosomal DNA Sequences". American Journal of Botany. 90 (1): 123–130. doi: 10.3732/ajb.90.1.123 . ISSN   1537-2197. PMID   21659087.
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