Drosera anglica | |
---|---|
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Caryophyllales |
Family: | Droseraceae |
Genus: | Drosera |
Subgenus: | Drosera subg. Drosera |
Section: | Drosera sect. Drosera |
Species: | D. anglica |
Binomial name | |
Drosera anglica | |
Synonyms [2] | |
List
|
Drosera anglica, commonly known as the English sundew [3] or great sundew, [4] is a carnivorous flowering plant species belonging to the sundew family Droseraceae. It is a temperate species with a circumboreal range, [2] 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. [5]
Drosera anglica is a perennial herb which forms an upright, stemless rosette of generally linear-spatulate leaves. As is typical for sundews, the laminae are densely covered with stalked reddish colored mucilaginous glands, each tipped with a clear droplet of a viscous fluid used for trapping insects. The lamina, which is 15–35 millimetres (0.59–1.38 in) long, [6] is held semi-erect by a long petiole, bringing the total leaf size to 30–95 millimetres (1.2–3.7 in). Plants are green, coloring red in bright light. In all populations except those in Kaua'i, D. anglica forms winter resting buds called hibernacula. These consist of a knot of tightly curled leaves at ground level, which unfurl in spring at the end of the dormancy period. The root system is weak and penetrates only a few centimeters, serving mainly as an anchor and for water absorption. Nitrogen is in short supply in bogs and trapping and digesting insects provides an alternate source.
Drosera anglica flowers in the summer, sending up peduncles 6–18 centimetres (2.4–7.1 in). long bearing several white flowers which open individually. Like other sundews, the flowers have five sepals, petals, and stamens with three styles. The petals for this species are 8–12 mm (¼ to ½") long, and the flowers have branched 2-lobed styles. [6] The odorless, nectar-less flowers do not rely on insect pollinators for pollination, rather setting seed well through self-pollination (autogamy). [7] The black roundish spindle-shaped seeds, [8] are 1 to 1+1⁄2 mm long. The fruits are a dehiscent three-valved capsule.
Like all sundews, D. anglica uses stalked mucilaginous glands called tentacles which cover its laminae to attract, trap, and digest small arthropods, usually insects. [9] These are attracted by a sugary scent exuded by the glands, and upon alighting on the plant adhere to the sticky drops of mucilage. Although most of its prey consists of small insects such as flies, bulkier insects with large wings are also caught. Small butterflies, damselflies, and even dragonflies can become immobilized by the plant's sticky mucilage.
The plant's initial response to contact with prey consists of thigmotropic (movement in response to touch) tentacle movement, with tentacles bending toward the prey and the center of the leaf to maximize contact. D. anglica is also capable of further movement, being able to bend the actual leaf blade around prey to further the digestion process. [9] Tentacle movement can occur in a matter of minutes, whereas the leaf takes hours or days to bend. When something gets caught, the tentacles touching the prey exude additional mucilage to mire down the prey, which eventually dies of exhaustion or is asphyxiated as the mucilage clogs its tracheae. Once the prey has been digested and the resulting nutrient solution has been absorbed by the plant, the leaf unfurls, leaving only the prey's exoskeleton behind.
Drosera anglica was given its first scientific description and named by the botanist William Hudson in 1778. Constantine Samuel Rafinesque proposed moving it and other species to a new genus named Adenopa in 1837, but this was not accepted. [2]
Drosera anglica grows in open, non-forested habitat with wet, often calcium-rich soils. These include bogs, marl fens, quaking bogs, cobble shores, and other calcareous habitats. [10] This tolerance of calcium is relatively rare in the rest of the genus. D. anglica is often associated with various sphagnum mosses, and many times grows in a soil substrate that is entirely composed of living, dead, or decomposed sphagnum. The sphagnum wicks moisture to the surface while simultaneously acidifying it. What soil nutrients are not seeped away by the constant moisture are often used up by the sphagnum or made unavailable by the low soil pH. Since nutrient availability is low, competition from other plants is diminished, allowing the carnivorous English sundew to flourish.
Drosera anglica is one of the most widely distributed sundews in the world. It is generally circumboreal, meaning that it is found at high latitudes around the globe. In a few areas, however, it is found farther south, particularly in Japan, southern Europe, the Hawaiian island of Kauaʻi, and California. Plants from Hawaiʻi, where it is known as mikinalo, are generally smaller than normal and do not experience a winter dormancy period. Its natural habitat includes 12 U.S. states, including Alaska, and 11 Canadian provinces and territories. [1] The altitudinal range is from 5 metres (20') to at least 2000 metres (6000'). [10] [11] In the US state of Minnesota, it was found in 1978 growing in shallow pools in peatlands with minerotrophic water dominated by low growing mosses and sedge species; because of its limited to small populations, and the type of microhabitats that it occupies, it is listed as a threatened species in the state. [8]
All North American Drosera species except for D. anglica have a chromosome count of 2n=20. In 1955, Wood noted that D. anglica had a chromosome count of 2n=40, and hypothesized that it was of hybrid amphidiploid origin. [12] Since the leaf morphology of D. anglica is an intermediary between that of D. rotundifolia and D. linearis and the two occur sympatrically in several locations, Wood conjectured that D. anglica likely originated from a hybrid between these two. [12]
All North American Drosera species produce sterile hybrids. The natural hybrid D. rotundifolia × D. linearis (conventionally but incorrectly referred to as Drosera ×anglica), is also sterile but is morphologically similar to the modern D. anglica. [5] Errors in meiosis during ovule and pollen production, however, can result in a chromosome doubling which can allow for viable seed to be produced. The resulting plants, known as amphiploids, would be fertile. Woods noted that this appeared to be an ongoing process with D. anglica speciating from D. rotundifolia × D. linearis through amphidiploidy in multiple locations. [12] The question remains as to why D. anglica is so widespread, whereas the range of D. linearis is limited to the Great Lakes region of North America. The greater adaptability of D. anglica to varied habitat conditions could be a major factor. [5]
Drosera anglica was first described by William Hudson in 1778. It has frequently been confused with the other circumpolar long-leaf Drosera, D. intermedia. This confusion was fueled by the resurfacing of an older name, D. longifolia (described by Carl Linnaeus in 1753), which was regarded as being too ambiguous in description and had been applied to specimens of both D. anglica and D. intermedia. Herbarium specimens were also a mix of the two species. These points led Martin Cheek to propose D. longifolia for rejection as a species name in 1998. [13] The proposal was accepted and the taxon listed as rejected in 1999. [14]
Several naturally occurring hybrids involving D. anglica exist. These include:
D. anglica × capillaris | = D. × anpil |
D. anglica × filiformis | = D. × anfil |
D. anglica × linearis | |
D. anglica × intermedia | = D. × anterm |
D. anglica × spatulata | = D. × nagamoto |
D. linearis × anglica | = D. × linglica |
D. rotundifolia × anglica | = D. × obovata |
These are all sterile. In addition, several man-made hybrids have been made.
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.
Droseraceae is a family of carnivorous flowering plants, also known as the sundew family. It consists of approximately 180 species in three extant genera. Representatives of the Droseraceae are found on all continents except Antarctica.
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.
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.
Drosera aliciae, the Alice sundew, is a carnivorous plant in the family Droseraceae. It is native to the Cape Provinces of South Africa, like Drosera capensis, the cape sundew, and is one of the most common sundews in cultivation. The plant forms small, tight rosettes of wedge-shaped leaves, up to 5 cm in diameter. Under conditions of good lighting, the insect-snagging tentacles will become deeply coloured with anthocyanin pigments, which probably aid in its attraction of insect prey. The plant is relatively easy to grow, and produces attractive scapes of pink flowers, which are held about 30 cm away from the carnivorous leaves, so as to prevent pollinators from becoming ensnared. D. aliciae is very similar in form to a number of other closely related species such as D. slackii, and D. natalensis: the former is rather larger with a slightly different growth habit(8 cm diameter); the latter has hairier stipules and a larger distance between leaf base and the “sticky” trichomes.
Drosera capensis, commonly known as the Cape sundew, is a small rosette-forming carnivorous species of perennial sundew native to the Cape in South Africa. Because of its size, easy-to-grow nature, and the copious amounts of seed it produces, it has become one of the most common sundews in cultivation, and thus, one of the most frequently introduced and naturalised invasive Drosera species.
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.
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.
Drosera intermedia, commonly known as the oblong-leaved sundew, spoonleaf sundew, or spatulate leaved sundew, is an insectivorous plant species belonging to the sundew genus. It is a temperate or tropical species native to Europe, southeastern Canada, the eastern half of the United States, Cuba, Hispaniola, and northern South America.
Pinhook Bog is a unique bog in Indiana that has been designated a National Natural Landmark. It is part of Indiana Dunes National Park, an area that many citizens, scientists, and politicians fought hard to preserve. Its sister bog, Volo Bog, is located nearby. The bog contains a large variety of plants, including insect eating plants, tamarack trees, stands of blueberry bushes, and floating mats of sphagnum moss. Pinhook Bog is about 580 acres (2.3 km2), a quarter of which is a floating mat of sphagnum peat moss. A "moat" separates the bog from the uplands.
Drosera tokaiensis is a species of sundew native to Japan. It is considered to be a natural hybrid of Drosera rotundifolia and Drosera spatulata. These two parent species have 20 and 40 chromosomes, respectively, so recent hybrids between them are sterile, having 30 chromosomes, while the stabilized, fertile D. tokaiensis has 60. The species was previously thought to be a subspecies or variety of Drosera spatulata. It is often mistaken for D. spatulata in cultivation.
Drosera burmanni, the tropical sundew, is a small, compact species in the carnivorous plant genus Drosera. Its natural geographical range includes the tropical and subtropical regions of Asia and Australia. It normally spans only 2 cm (0.8 in) in diameter. It is one of the fastest trapping sundews as well, and its leaves can curl around an insect in only a few seconds, compared to the minutes or hours it takes other sundews to surround their prey. In nature, D. burmanni is an annual, but in cultivation, when grown indoors during the cold months, it can live for many years. Since D. burmanni is an annual, it produces large amounts of seed. Drosera burmanni has been considered a powerful rubefacient in Ayurveda.
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.
Drosera glanduligera, commonly known as the pimpernel sundew or scarlet sundew, is a species of carnivorous plant endemic to southern Australia. It is an ephemeral annual plant that grows in the winter and flowers from August to November.
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.
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..
Drosera kaieteurensis is a plant from the sundew family (Droseraceae).
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.
Toxomerus basalis, commonly known as the sundew flower fly, is a species of kleptoparasitic fly endemic to Brazil. It was first described by Francis Walker in 1836. It feeds on captured, immobilized insects caught on the sticky leaves of sundew plants, which are carnivorous. Adult flies seem to have some capacity to escape from Drosera leaves if they have not come into contact with too many of the tentacles. The species is non-specific and have been found on large-leaved, semi-erect, and thread-like Drosera species, such as Drosera graomogolensis and Drosera magnifica.