Drosera capensis

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Cape sundew
Drosera capensis bend.JPG
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Droseraceae
Genus: Drosera
Subgenus: Drosera subg. Drosera
Section: Drosera sect. Drosera
Species:
D. capensis
Binomial name
Drosera capensis
L.

Drosera capensis, commonly known as the Cape sundew, [1] [2] is a small rosette-forming carnivorous species of perennial [3] 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.

Description

Drosera capensis 'Alba' Drosera capensis ,,Alba,, growing in peat moss and airsoft pellets mix.jpg
Drosera capensis 'Alba'

D. capensis produces strap-like leaves, up to 3.5 centimetres (1.4 in) long (not including the petiole) and 0.5 centimetres (0.2 in) wide, [4] which, as in all sundews, are covered in brightly coloured tentacles which secrete a sticky mucilage that traps arthropods. It is a perennial, herbaceous plant that forms a rosette with a diameter of 18 to 25 cm (7.1 to 9.8 in) and is characterized by numerous, reddish glandular erosions on 7 cm (2.8 in) long and 5 mm (0.20 in) wide, elongated leaves.

The plant flowers in summer (December and January in its native habitat in South Africa) with up to fifty pale-violet, over 2-centimetre (0.79 in) large flowers, borne on up to 35 cm (14 in) high racemose inflorescences. The flowers can self-pollinate upon closing and produce copious quantities of very small, spindle-shaped seeds, which are released from the capsules that form when the flowers have died. The plant thrives in full sun locations on nutrient-poor, waterlogged and lime-free soils.

Carnivorous adaptations

Drosera capensis eating a fruit fly ( Ceratitis capitata ), time-lapse video, 1 frame per 90 seconds, over approximately six hours.

Drosera capture insects by luring them with their glossy, magenta-hued beads of false "nectar" (seen covering the tentacles of healthy leaves); this nectar is, of course, merely sticky droplets made-up of digestive enzymes. The secretions act as a visual attractant to nearby insects, as it shines in the sun (hence the common name of sundew). Furthermore, when Drosera plants come into bloom, the flowers themselves bring more potential prey to the vicinity of the plant.

At first, when a prey item such as an insect, is stuck to a Drosera leaf, it may find itself deeply trapped, right away, or only partly stuck (based on the angle of its initial landing); if not fully stuck, the movements of the prey trying to wriggle free will often trigger the leaf-tip to fold back onto itself to ensure the bug cannot escape. However, this does not always occur; the insect may simply remain stuck to (and ultimately digested on) an open leaf. The action itself is comparable to a person extending one arm outwards, and rolling their hand back, much like a "bicep curl". Not only does this action serve to further secure the sundew’s victim, but it allows for more leaf surface area (and thus, digestive enzymes) to come into contact with the prey, ensuring digestion. Once the prey is fully trapped, initial breakdown often begins within an hour; wriggling or attempting to escape will only trap the insect further. Digestion takes well-over six hours from the time of an insect's initial landing.

If a prey organism has been caught in the secretion of the tentacles, then the tentacles near the victim will bend towards it, until a portion of the tentacle-covered region of the leaf has wrapped around the animal. Secreted enzymes will digest the insect until only the chitin remains. The absorption of nutrients takes place via the tentacle tips, where the secretion itself is produced. When the prey item is decomposed enough that the plant cannot gain further nutrients, the leaf and the tentacles return to their original position. [5]

A fly 12 hours into being trapped by a cape sundew. DroseraWithFly.jpg
A fly 12 hours into being trapped by a cape sundew.

The sundew secretes mucin to trap its prey, which consists of a variety of species, including bees, small wasps, beetles; fruit flies such as Drosophila and Ceratitis capitata ; Diptera, like fungus gnats and house flies; lacewings, and other arthropods. The plant may occasionally catch aphids or mealybugs, which are drawn to the sticky leaves, as they attempt to feed on the crown of the plant—Drosera are not immune to destructive sucking insects and other pests. The mucin is an approximately four-percent aqueous solution of an acidic polysaccharide, with a pH of around 4. The mucin secretions of Drosera capensis have a high viscosity; fresh mucin can be stretched into a thread up to a meter in length. This suggests that the mucin is predominantly composed of acidic polysaccharide; these polysaccharides interact extensively and are highly hydrated. [6]

Drosera capensis has two color-forms: red-tentacled and white-tentacled. It has been hypothesized that visual cues, such as tentacle coloration, could be a factor in prey attraction in carnivorous plants, in addition to the olfactory signals used. In prey-attractant experiments, Drosophila melanogaster fruit flies were introduced to the red- and white-colored forms of D. capensi in the laboratory. The D. melanogaster seemed to have no preference for color of plant tentacles, as there was no difference in the mean number of the flies captured between the two forms of the sundew. Coloration in D. capensis is due to anthocyanin pigment – or the lack of – and does not affect the ultraviolet (UV) coloration of the plant. It is the UV coloration which, along with olfactory signals, appears to important in attracting prey. Increased photosynthesis was observed in plants fed with fruit flies. [5]

Reproduction

In early summer or late spring, D. capensis produces multiple, small, five-petaled pink flowers at the end of scapes which can be up to 30 centimetres (1 ft) tall. [4] Flowers individually open in the morning and close by mid-afternoon, lasting just one day each with the next one up the scape opening the following day; the lower ones on the scape can thus be open or "past" while the ones at the top are still forming.

Under horticultural conditions, carnivorous plant enthusiasts find that these seeds have a tendency to find their way into neighbouring plant pots where they germinate readily, giving D. capensis a reputation as a weed.

Cultivation

Drosera capensis uses its sticky tentacles to attract and catch flies and other insects. Contact triggers a curling reaction, where the plant wraps up its prey and eventually digests and absorbs the victim's nutrients. This scene is about 4 hours in real-time.
Inflorescence of Drosera capensis Drosera capensis inflorescence Darwiniana.jpg
Inflorescence of Drosera capensis

Drosera capensis has several forms or varieties, including the "typical", "wide-leaved", "narrow-leaved" and "red" forms and the cultivar Drosera 'Albino'. [7] The typical form is noted for wider leaves and the gradual production of a scrambling stem as it grows. The "wide-leaved" form is similar to the "typical" variety, but produces leaves at least 50 percent wider than the typical variety. The narrow-leaved form differs from the typical form in that it rarely produces tall stems; has thinner, longer leaves and less hair on the plant. Drosera capensis 'Albino', is also similar in shape to the "typical" form, but lacks most of the red pigmentation of the typical or narrow forms, with clear or pink trichomes and white flowers. There is also the "red" form that turns blood red in full sunlight, and is also similar physically to the narrow-leaved form. These varieties are commercially available. [7]

Drosera capensis "narrow-leaved" has won the Royal Horticultural Society's Award of Garden Merit. [8]

Drosera capensis can be easily propagated through a variety of methods including seed, leaf cuttings, and root cuttings. It is not easily killed by temperature extremes of a short duration and is a generally forgiving plant to grow. Additionally, D. capensis does not undergo dormancy like some sundews. It is among the easiest of carnivorous plants to keep indoors. It grows very well in open air, on a sunny windowsill, as long as it is kept in an inch or two of mineral-free water. [7] It does not require a terrarium although it can benefit from one.

The ideal substrate is composed of 70 percent of blonde peat and 30 percent of non-calcareous sand. The ideal temperature varies between 5 and 15 °C (41 and 59 °F) in winter and between 20 and 40 °C (68 and 104 °F) in summer, for a hygrometry of 40 to 80 percent. Moist soil must be maintained year-round by the presence of a saucer under the pot, but watering must be reduced and the saucer removed in winter. High ambient humidity allows the preservation of mucilage. An exposure in full sun suits it perfectly, although a place a little less sunny may be suitable.

Invasive species

Drosera capensis is listed on the New Zealand National Pest Plant Accord due to it being classified as an invasive species in that country, where they cannot be bought at plant retailers and should not be traded by carnivorous plant partisans. They have been planted in the wild or unintentionally introduced through soil contaminated by seeds with plantings of pitcher plants and water lilies. They are now beginning to spread on their own, potentially with help from water birds. [9]

Drosera capensis have also been found in Australia. Currently it has only been found in New South Wales but understanding the species distribution is essential to managing the species in the future. It has also been found in the state of California and classified as a naturalized weed. Alongside Australia, California and New Zealand, Drosera capensis have also been found in peat bogs in South America. [10] It is currently classified as an invasive species.

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">Droseraceae</span> Family of carnivorous flowering plants

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.

<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 110 of a second from initial contact.

<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>Roridula</i> Insect-trapping shrublet from South Africa

Roridula is a genus of evergreen, insect-trapping shrubs, with two species, of about 1⅓–2 m. It is the only genus in the family Roridulaceae. It has thin, woody, shyly branching, upright, initially brown, later grey stems, with lance- to awl-shaped leaves crowded at their tips. The star-symmetrical flowers consist from the outside in of five, green or reddish, free sepals, alternating with five white, pink or purple, free petals. Further to the middle and opposite the sepals are five stamens with the anthers initially kinked down. These suddenly flip up if the nectar-containing swelling at its base is being touched. The center of the flower is occupied by a superior ovary. The leaves and sepals carry many sticky tentacles of different sizes, that trap insects. Roridula does not break down the insect proteins, but bugs of the genus Pameridea prey on the trapped insects. These later deposit their feces on the leaves, which take up nutrients from the droppings. The species can be found in the Western Cape province of South Africa. They are commonly known as dewstick or fly bush in English and vlieëbos or vlieëbossie in Afrikaans.

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

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.

<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 spatulata</i> Species of plant

Drosera spatulata, the spoon-leaved sundew, is a variable, rosette-forming sundew with spoon-shaped leaves. The specific epithet is Latin for "spatula shaped," a reference to the form of the leaves. This sundew has a large range and occurs naturally throughout Southeast Asia, southern China and Japan, Micronesia, Papua New Guinea, eastern Australia, Tasmania and New Zealand. Variants are often known by the localities in which they are found. The plant does not form hibernacula in winter, and is easily grown using the same methods as Drosera capensis.

<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>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.

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

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.

<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">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 glanduligera</i> Species of carnivorous plant

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.

<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.

<span class="mw-page-title-main">Tentacle (botany)</span>

In botany, tentacles are glandular hairs on the leaves of some species of insectivorous plants such as Drosera (sundews). Tentacles are different from organs such as the tendrils of climbing plants.

The tissues that are concerned with the secretion of gums, resins, volatile oils, nectar latex, and other substances in plants are called secretory tissues. These tissues are classified as either laticiferous tissues or glandular tissues.

<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.

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

Drosera pulchella, a type of pygmy sundew , is a species of carnivorous plant native to southwestern Australia. As their common name suggests, they are a small species that usually 15 to 20 millimeters wide. They typically grow in clusters that completely cover an area like a patch of moss. The namesake sticky dew at the ends of their leaves is designed to trap insects so that the plants can absorb nutrients as the insect decomposes.

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.

References

  1. BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
  2. USDA, NRCS (n.d.). "Drosera capensis". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 18 January 2016.
  3. The Reader's Digest Gardeners Encyclopedia of Plants and Flowers, Reader's Digest Association, 1992
  4. 1 2 Slack, Adrian. 2000. Carnivorous Plants. Revised edition. MIT Press: Cambridge, Massachusetts. pp. 136.
  5. 1 2 Pavlovič, Andrej; Krausko, Miroslav; Libiaková, Michaela; Adamec, Lubomír (January 2014). "Feeding on prey increases photosynthetic efficiency in the carnivorous sundew Drosera capensis". Annals of Botany. 113 (1): 69–78. doi:10.1093/aob/mct254. ISSN   1095-8290. PMC   3864725 . PMID   24201141.
  6. Rost, Karl; Schauer, Roland (January 1977). "Physical and chemical properties of the mucin secreted by Drosera capensis". Phytochemistry. 16 (9): 1365–1368. Bibcode:1977PChem..16.1365R. doi:10.1016/S0031-9422(00)88783-X.
  7. 1 2 3 Cape Sundews, "The Savage Garden: Cultivating Carnivorous Plants", Peter D'Amato, 1998
  8. "Drosera capensis 'narrow-leaved'". www.rhs.org. Royal Horticultural Society. Retrieved 1 June 2020.
  9. Carnivorous weeds in Auckland
  10. Jobson, Richard W.; Conn, Barry J. (2012-12-21). "Drosera capensis (Droseraceae), a new naturalised record for Australia". Telopea. 14: 89–92. doi: 10.7751/telopea2012015 .