The VENUS FLYTRAP (also referred to as VENUS\'S FLYTRAP or VENUS\' FLYTRAP), DIONAEA MUSCIPULA, is a carnivorous plant native to subtropical wetlands on the East Coast of the United States in North Carolina and South Carolina . It catches its prey—chiefly insects and arachnids —with a trapping structure formed by the terminal portion of each of the plant's leaves, which is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap prepares to close, snapping shut only if another contact occurs within approximately twenty seconds of the first strike. The requirement of redundant triggering in this mechanism serves as a safeguard against wasting energy by trapping objects with no nutritional value, and the plant will only begin digestion after five more stimuli to ensure it has caught a live bug worthy of consumption.
* 1 Description * 2 Etymology
* 3 Carnivory
* 3.1 Prey selectivity * 3.2 Mechanism of trapping * 3.3 Digestion
* 4 Evolution
* 4.1 Proposed evolutionary history
* 5 Habitat
* 6 Cultivation
* 6.1 Cultivars
* 7 Conservation * 8 In alternative medicine * 9 See also * 10 References * 11 External links
“The great wonder of the vegetable kingdom is a very curious unknown species of Sensitive. It is a dwarf plant. The leaves are like a narrow segment of a sphere, consisting of two parts, like the cap of a spring purse, the concave part outwards, each of which falls back with indented edges (like an iron spring fox-trap); upon anything touching the leaves, or falling between them, they instantly close like a spring trap, and confine any insect or anything that falls between them. It bears a white flower. To this surprising plant I have given the name of Fly-trap Sensitive.”
This seems to be the earliest notice of the plant and is before any letters from John Ellison on the subject.
The Venus flytrap is a small plant whose structure can be described as a rosette of four to seven leaves, which arise from a short subterranean stem that is actually a bulb-like object. Each stem reaches a maximum size of about three to ten centimeters, depending on the time of year; longer leaves with robust traps are usually formed after flowering. Flytraps that have more than seven leaves are colonies formed by rosettes that have divided beneath the ground. Illustration from Curtis\'s Botanical Magazine by William Curtis (1746–1799)
The leaf blade is divided into two regions: a flat, heart-shaped photosynthesis -capable petiole , and a pair of terminal lobes hinged at the midrib, forming the trap which is the true leaf. The upper surface of these lobes contains red anthocyanin pigments and its edges secrete mucilage . The lobes exhibit rapid plant movements , snapping shut when stimulated by prey. The trapping mechanism is tripped when prey contacts one of the three hair-like trichomes that are found on the upper surface of each of the lobes. The mechanism is so highly specialized that it can distinguish between living prey and non-prey stimuli, such as falling raindrops; two trigger hairs must be touched in succession within 20 seconds of each other or one hair touched twice in rapid succession, whereupon the lobes of the trap will snap shut, typically in about one-tenth of a second. The edges of the lobes are fringed by stiff hair-like protrusions or cilia, which mesh together and prevent large prey from escaping. These protrusions, and the trigger hairs (also known as sensitive hairs) are likely homologous with the tentacles found in this plant’s close relatives, the sundews . Scientists have concluded that the snap trap evolved from a fly-paper trap similar to that of Drosera.
The holes in the meshwork allow small prey to escape, presumably because the benefit that would be obtained from them would be less than the cost of digesting them. If the prey is too small and escapes, the trap will usually reopen within 12 hours. If the prey moves around in the trap, it tightens and digestion begins more quickly.
Speed of closing can vary depending on the amount of humidity, light,
size of prey, and general growing conditions. The speed with which
traps close can be used as an indicator of a plant's general health.
Venus flytraps are not as humidity-dependent as are some other
carnivorous plants, such as
The Venus flytrap exhibits variations in petiole shape and length and whether the leaf lies flat on the ground or extends up at an angle of about 40–60 degrees. The four major forms are: 'typica', the most common, with broad decumbent petioles; 'erecta', with leaves at a 45-degree angle; 'linearis', with narrow petioles and leaves at 45 degrees; and 'filiformis', with extremely narrow or linear petioles. Except for 'filiformis', all of these can be stages in leaf production of any plant depending on season (decumbent in summer versus short versus semi-erect in spring), length of photoperiod (long petioles in spring versus short in summer), and intensity of light (wide petioles in low light intensity versus narrow in brighter light).
Flowering venus flytrap showing its long flower stem
Closeup of flower (c. 20 mm in diameter)
The species produces small, shiny black seeds
The plant's common name refers to Venus , the Roman goddess of love.
The genus name, Dionaea ("daughter of Dione "), refers to the Greek
Historically, the plant was also known by the slang term "tipitiwitchet" or "tippity twitchet", possibly an oblique reference to the plant's resemblance to human female genitalia.
A closing trap
Play media A time lapse showing Venus flytrap catching prey
Most carnivorous plants selectively feed on specific prey. This
selection is due to the available prey and the type of trap used by
the organism. With the Venus flytrap, prey is limited to beetles,
spiders and other crawling arthropods. In fact, the Dionaea diet is
33% ants, 30% spiders, 10% beetles, and 10% grasshoppers, with fewer
than 5% flying insects. Given that Dionaea evolved from an ancestral
MECHANISM OF TRAPPING
Closeup of one of the hinged trigger hairs
The mechanism by which the trap snaps shut involves a complex interaction between elasticity , turgor and growth. The trap only shuts when there have been two stimulations of the trigger hairs; this is to avoid inadvertent triggering of the mechanism by dust and other wind-borne debris. In the open, untripped state, the lobes are convex (bent outwards), but in the closed state, the lobes are concave (forming a cavity). It is the rapid flipping of this bistable state that closes the trap, but the mechanism by which this occurs is still poorly understood. When the trigger hairs are stimulated, an action potential (mostly involving calcium ions—see calcium in biology ) is generated, which propagates across the lobes and stimulates cells in the lobes and in the midrib between them. It is hypothesized that there is a threshold of ion buildup for the Venus flytrap to react to stimulation. After closing, the flytrap counts additional stimulations of the trigger hairs, to five total, to start the production of digesting enzymes. The acid growth theory states that individual cells in the outer layers of the lobes and midrib rapidly move 1H+ (hydrogen ions ) into their cell walls, lowering the pH and loosening the extracellular components, which allows them to swell rapidly by osmosis , thus elongating and changing the shape of the trap lobe. Alternatively, cells in the inner layers of the lobes and midrib may rapidly secrete other ions , allowing water to follow by osmosis, and the cells to collapse. Both of these mechanisms may play a role and have some experimental evidence to support them.
If the prey is unable to escape, it will continue to stimulate the inner surface of the lobes, and this causes a further growth response that forces the edges of the lobes together, eventually sealing the trap hermetically and forming a "stomach" in which digestion occurs. Release of the digestive enzymes is controlled by the hormone jasmonic acid , the same hormone that triggers the release of toxins as an anti-herbivore defense mechanism in non-carnivorous plants. (See Evolution below) Once the digestive glands in the leaf lobes have been activated, digestion is catalysed by hydrolase enzymes secreted by the glands.
Oxidative protein modification is likely to be a pre-digestive
mechanism used by Dionaea muscipula. Aqueous leaf extracts have been
found to contain quinones such as the naphthoquinone plumbagin that
couples to different
NADH -dependent diaphorases to produce superoxide
and hydrogen peroxide upon autoxidation . Such oxidative modification
could rupture animal cell membranes.
Digestion takes about ten days, after which the prey is reduced to a husk of chitin . The trap then reopens, and is ready for reuse.
Carnivory in plants is a very specialized form of foliar feeding , and is an adaptation found in several plants that grow in nutrient-poor soil. Carnivorous traps were naturally selected to allow these organisms to compensate for the nutrient deficiencies of their harsh environments by supplementing ordinary photosynthate with animal proteins.
The "snap trap" mechanism characteristic of Dionaea is shared with only one other carnivorous plant genus, Aldrovanda . For most of the 20th century, this relationship was thought to be coincidental, more precisely an example of convergent evolution . Some phylogenetic studies even suggested that the closest living relatives of Aldrovanda were the sundews . It was not until 2002 that a molecular evolutionary study, by analyzing combined nuclear and chloroplast DNA sequences, indicated that Dionaea and Aldrovanda were closely related and that the snap trap mechanism evolved only once in a common ancestor of the two genera.
A 2009 study presented evidence for the evolution of snap traps of
Aldrovanda from a flypaper trap like
In 2016, a study of the expression of genes in the plant's leaves as they captured and digested prey was published in the journal, Genome Research . The gene activation observed in the leaves of the plants gives support to the hypothesis that the carnivorous mechanisms present in the flytrap are a specially adapted version of mechanisms used by non-carnivorous plants to defend against herbivorous insects. In many non-carnivorous plants, jasmonic acid serves as a signaling molecule for the activation of defense mechanisms, such as the production of hydrolases, which can destroy chitin and other molecular components of insect and microbial pests. In the Venus flytrap, this same molecule has been found to be responsible for the activation of the plant's digestive glands. A few hours after the capture of prey, another set of genes is activated inside the glands, the same set of genes that is active in the roots of other plants, allowing them to absorb nutrients. The use of similar biological pathways in the traps as non-carnivorous plants use for other purposes indicates that somewhere in its evolutionary history, the Venus flytrap repurposed these genes for the purpose of carnivory.
PROPOSED EVOLUTIONARY HISTORY
Carnivorous plants are generally herbs, and their traps the result of primary growth . They generally do not form readily fossilizable structures such as thick bark or wood. As a result, there is no fossil evidence of the steps that might link Dionaea and Aldrovanda, or either genus with their common ancestor, Drosera. Nevertheless, it is possible to infer an evolutionary history based on phylogenetic studies of both genera. Researchers have proposed a series of steps that would ultimately result in the complex snap-trap mechanism:
* Larger insects usually walk over the plant, instead of flying to
it, and are more likely to break free from sticky glands alone.
Therefore, a plant with wider leaves, like
Map of the original distribution of the Venus flytrap
Venus flytrap is found in nitrogen - and phosphorus-poor
environments, such as bogs and wet savannahs. Small in stature and
Venus flytrap tolerates fire well, and depends on
periodic burning to suppress its competition. Fire suppression
threatens its future in the wild. It survives in wet sandy and peaty
soils. Although it has been successfully transplanted and grown in
many locales around the world, it is native only to the coastal bogs
of North and
South Carolina in the United States, specifically within
a 60-mile radius of Wilmington,
North Carolina . One such place is
North Carolina's Green Swamp . There also appears to be a naturalized
population of Venus flytraps in northern
Dionaea muscipula 'Akai Ryu', Japanese for 'Red Dragon', in cultivation
Venus flytraps are popular as cultivated plants, but have a reputation for being difficult to grow. Successfully growing these specialized plants requires recreating a close approximation to the plant's natural habitat.
Healthy Venus flytraps will produce scapes of white flowers in spring ; however, many growers remove the flowering stems early (2–3 inches), as flowering consumes some of the plant's energy and thereby reduces the rate of trap production. If healthy plants are allowed to flower, successful pollination will result in seeds.
Plants can be propagated by seed, taking around four to five years to reach maturity. More commonly, they are propagated by clonal division in spring or summer. Venus flytraps can also be propagated in vitro using plant tissue culture . Most Venus flytraps found for sale in nurseries garden centers have been produced using this method, as this is the most cost-effective way to propagate them on a large scale. Regardless of the propagation method used, the plants will live for 20 to 30 years if cultivated in the right conditions.
Main article: List of Venus flytrap cultivars
Venus flytraps are by far the most commonly recognized and cultivated carnivorous plant, and they are frequently sold as houseplants. Various cultivars (cultivated varieties) have come into the market through tissue culture of selected genetic mutations, and these plants are raised in large quantities for commercial markets.
The species is classified as "vulnerable" by the National Wildlife Federation . In 2015, there were estimated to be fewer than 33,000 plants in the wild, all within 75 miles (121 km) of the city of Wilmington, North Carolina, and all on sites owned by The Nature Conservancy , the North Carolina state government, or the US military.
In 2014, the state of North Carolina passed Senate Bill 734 which classifies the theft of naturally growing Venus flytraps in the state as a felony. Tougher sanctions and penalties for the theft were also enacted in December 1, 2014 in accordance with legislation.
IN ALTERNATIVE MEDICINE
Venus flytrap extract is available on the market as an herbal remedy
, sometimes as the prime ingredient of a patent medicine named
"Carnivora". According to the
American Cancer Society
* ^ Schnell, D.; Catling, P.; Folkerts, G.; Frost, C.; Gardner, R.;
et al. (2000). "Dionaea muscipula".
IUCN Red List