The Venus Flytrap is known for its trapping leaves. When an insect lands on the inner part of a leaf, it touches trigger hairs. This causes the leaf to snap shut. Teeth on the edge of the trap keep the insect from escaping. The trap then slowly digests the insect.
- Dionaea muscipula.” Wikipedia, The Free Encyclopedia. Available from: http://en.wikipedia.org/wiki/Dionaea_muscipula
- “Droseraceae.” Wikipedia, The Free Encyclopedia. Available from: http://en.wikipedia.org/wiki/Droseraceae
- "Dionaea muscipula". Encyclopedia of Life, available from:http://eol.org/pages/584643/details
Regularity: Regularly occurring
Regularity: Regularly occurring
Global Range: This species is endemic to a narrow region entirely within the outer coastal plain of North Carolina and South Carolina, ranging from Pamlico County, North Carolina (North Carolina Natural Heritage Program 2010) south to Charleston County, South Carolina (historic population only; Pittman pers. comm.). Roberts and Oosting (1958) concluded that its total range is probably determined by its being exclusively limited to soils having a high water table, an organic hardpan usually not more than 60 cm below the surface, and a pH range of 3.9-4.5. Venus flytraps have been transplanted by well-intentioned but ecologically misguided people to the Pine Barrens of New Jersey (Snyder 1989) and to the Apalachicola National Forest in the Florida panhandle (Clewell 1985, Sorrie 1991). In each instance, a single small population survives, apparently unable to increase appreciably in size. These extra-limital transplants are considered inconsequential to the conservation of the species.
Venus flytrap is currently extant in 11 counties in North Carolina and one county in South Carolina (North Carolina Natural Heritage Program 2010, Pittman pers. comm.). Largest concentrations of this species are in Brunswick, Carteret, Onslow, and Pender Counties in North Carolina. This species has been nearly extirpated in the central coastal plain of North Carolina, and persists in the Sandhills of North Carolina only at a few sites in Fort Bragg (North Carolina Natural Heritage Program 2010). A feeble, exotic population is also found in Escambia County, Alabama (Schotz pers. comm.).
Current range: The range of Venus flytrap is quite localized in scattered savannas of the coastal plain of southeastern North Carolina and adjacent eastern South Carolina in an approximate landward radius of 100 miles around Wilmington, North Carolina (North Carolina Natural Heritage Program 2010). Currently 68 extant occurrences are known from the following counties in North Carolina (the number of occurrences in parentheses): Bladen (5), Brunswick (21), Carteret (1), Columbus (3), Craven (1), Cumberland (4), Hoke (7), New Hanover (5), Onslow (12), Pender (7), and Sampson (2) (North Carolina Natural Heritage Program 2010), and Horry County (4), South Carolina (South Carolina Heritage Trust 1993b).
24 occurrences in North Carolina were not relocated during the most recent surveys, but there are reasons to believe they are still present (the populations may have been difficult to relocate due to fire suppression or vague directions).
Historic range: Dionaea muscipula was first reported from Brunswick County, North Carolina, by Governor Dobbs in 1759 (Roberts and Oosting 1958). In 1958 its reported range extended from Chocowinity, Beaufort County, North Carolina, in the north, to the Santee River, South Carolina, in the south, and westward to the Sandhills region of Moore County, North Carolina (Roberts and Oosting 1958). Radford, et al. (1968), report Venus flytraps from 17 counties in North Carolina (Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven, Cumberland, Duplin, Jones, Lenoir, Moore, New Hanover, Onslow, Pamlico, Pender, Robeson, and Sampson counties) and three counties in South Carolina (Charleston, Georgetown, and Horry counties). Buchanan (2010) lists it from 18 counties in North Carolina, with the addition of Hoke.
There are 31 known occurrences in North Carolina which are currently considered extirpated or historic. These occurrences were located in the following counties: Bladen, Brunswick, Carteret, Columbus, Craven, Cumberland, Duplin, Lenoir, Moore, New Hanover, Onslow, Pamlico, Pender, and Robeson (North Carolina Natural Heritage Program Database 2010). In South Carolina there are 26 occurrences considered extirpated or historic in the following counties: Charleston, Georgetown, and Horry (South Carolina Heritage Trust 1993b). The high number of extirpated occurrences is indicative of the real threats to and continued decline of the species.
"The outstanding features of the flytrap are the three irritable cilia on the face of each leaf-lobe which transmit the stimulus that causes the paired lobes to snap shut on an insect, and the eyelash-like cilia of the lobes which close together like the fingers when one's hands are folded, thus making sure the victim is securely held" (Small, 1933).
Comments: Dionaea muscipula occupies distinct habitats in the two regions of the Carolinas (Fall-line Sandhills and Outer Coastal Plain) where it is found.
In the Outer Coastal Plain, where it is more common, Dionaea muscipula occurs in broad ecotonal areas between Pine Savannas or Wet Pine Flatwoods and pocosins (evergreen shrub bogs). These sites are generally flat with wet or moist soils for much of the year. The species rarely occurs in seasonally flooded depressions, although it may occur along the edges of such sites.
In the Sandhills region, it is limited to narrow, moist ecotones between Streamhead Pocosins (linear, evergreen shrub bogs along small creeks and their headwaters) and longleaf pine/scrub oak/wiregrass uplands and along the vegetatively similar ecotones between Sandhill Seeps and longleaf pine uplands. Sandhill Seeps are sphagnous, shrub-and-herb-dominated areas occurring in relatively steep places where local clay soils force seepage water to the surface. Soils in these ecotonal areas are usually highly acidic, loamy sands.
Soils associated with Dionaea sites on the Outer Coastal Plain tracked by the North Carolina Natural Heritage Program (1993) include Baymeade (Arenic Hapludults), Blaney (Arenic Hapludults), Foreston (Aquic Paleudults), Grifton (Typic Orchraqualfs), Johnston (Cumulic Humaquepts), Kureb (Spodic Quartzipsamments), Leon (Aeric Haplaquods), Murville (Typic Haplaquods), Onslow (Spodic Paleudults), Pactolus (Aquic Quartzipsamments), and Woodington (Typic Paleaquults) (Hudson 1984, Barnhill 1986, North Carolina Natural Heritage Program 1993). The Pine Savanna ecotones that Dionaea muscipula occupies in the Outer Coastal Plain are generally dominated by an open to moderate canopy of Pinus palustris (often with a mixture of Pinus serotina or even Taxodium ascendens), over a dense, species-rich ground layer with grasses, sedges, herbs and low-growing shrubs. Associated species at Dionaea muscipula sites can vary considerably, but graminoids such as Muhlenbergia expansa, Ctenium aromaticum, Sporobolus sp. 1, and Aristida stricta (to a lesser extent) usually dominate. Other common species include Rhexia alifanus, Aletris spp., Zigadenus spp., Polygala spp., orchids, Eupatorium spp., Dichanthelium spp., Xyris caroliniana, and rare plants such as Tofieldia glabra, Solidago pulchra, Oxypolis ternata, and Rhynchospora pallida. Other insectivorous plants that almost always co-occur with flytraps include species of Pinguicula, Sarracenia, and Drosera. Common shrub species include Ilex glabra, Vaccinium crassifolium, Gaylussacia frondosa, Kalmia carolina, Myrica cerifera, and Lyonia mariana (LeBlond 1993). If frequently burned, these ecotones will remain herb-dominated and species-rich. Fire suppression generally leads to shrub and tree invasion and a gradual decline in species diversity.
Ecotones in the Sandhills region are quite similar in species composition to Outer Coastal Plain savanna ecotones, although they are generally much narrower in size. Dionaea muscipula is usually found along the lower, pocosin edges of well-burned ecotones, in areas dominated by a mixture of low shrubs, cane, and a high diversity of herbs. Species counts in these well-burned sites are often impressively high; a 1/100 hectare (10 x 10 meters) plot of a Sandhill Seep ecotone on Fort Bragg yielded over 100 species, one of the highest known species richness counts in temperate North America (Schafale and Weakley 1990). Commonly associated herbs include Aletris farinosa, A. aurea, Andropogon glomeratus, Aristida stricta, Arundinaria tecta, Calamagrostis cinnoides, Calamovilfa brevipilis, Chasmanthium laxum, Ctenium aromaticum, Dichanthelium spp., Drosera spp., Eriocaulon decangulare, Eupatorium pilosum, Juncus trigonocarpus, Lachnocaulon anceps, Lycopodiella spp., Panicum virgatum var. cubense, Platanthera spp., Polygala spp., Pteridium aquilinum var. pseudocaudatum, Rhexia alifanus, R. petiolata, Rhynchospora spp., Sarracenia purpurea, S. rubra, Scleria minor, Solidago stricta, and Xyris spp. Rare plants associated with Dionaea include Lysimachia asperulifolia, Oxypolis ternata, Rhynchospora pallida, R. stenophylla, and Tofieldia glabra. Shrubs such as Lyonia lucida, L. ligustrina var. foliosiflora, Vaccinium corymbosum, Leucothoe racemosa, Gaylussacia frondosa, Clethra alnifolia, Ilex glabra, I. coriacea, and Aronia arbutifolia are also present and will dominate during periods of fire suppression. In SC, one extant population occurs along the ecotone of a sand rim between two Carolina bays (South Carolina Heritage Trust 1993b) In NC, two occurrences are found in similar situations, in the ecotone between a sand rim and a Carolina bay, one each in Brunswick (1982) and Bladen (1981) counties (NCNHP 1993). Dionaea will sometimes colonize disturbed areas, such as rights-of-way and roadsides, if competition is minimized by constant cutting or burning. In these situations, soil and water conditions are very similar to natural occurrences.
Found in association with wet, mineral soils within wet longleaf pine communities: pine savannas, wet pine flatwoods and sandhill seeps (Schafale pers. comm.). Roberts and Oosting (1958) concluded that its range is probably limited by its requirements for a high water table, an organic hardpan under 60cm below the surface, and a pH range of 3.9-4.5 (Russo 1993). This species is typically in full sun with other insectivorous plants (Kral 1983). Most frequently in association with openings in pocosins or in pineland savanna, predominantly with longleaf pine overstory (Kral 1983). Occasionally occurs with pond pine adjacent to bay rims (Pittman pers. comm.). This species also occurs in narrow transitional ecotones between sandhills and pocosins (Schafale pers. comm.). Within these habitats, it can establish and persist along roadsides and in powerline corridors (Schafale pers. comm.), or where heavy logging has taken place adjacent to large seed sources (Kral 1983). This species and its communities depend on regular fires to maintain their open character (Frost pers. comm.; Kral 1983); it will not persist in the shade of pine plantations (Kral 1983).
Habitat and Ecology
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 21 - 300
Comments: 75-100 populations are extant rangewide. North Carolina: 68 extant/31 historic/24 failed to relocate in recent searches (North Carolina Natural Heritage Program 2010); South Carolina: 6 (Pittman pers. comm.); Alabama: 1 feeble population, introduced (Schotz pers. comm.); Florida: few, introduced and persisting (Schotz pers. comm.; Morse pers. comm.); New Jersey: 1, introduced, persisting (Evert 1957, Weakley 1996, Sorrie 1991). [JRB]
A few of the historic populations might still be extant (Buchanan pers. comm. 2010). [JRB]
This is a highly fire-dependent species. Fire return intervals any greater than one or two years result in population crashes after a period of approximately 5 years (Frost pers. comm.). [JRB]
There is a globally rare moth (G1) that specializes on Dionaea (Schafale pers. comm.). [JRB]
Life History and Behavior
Reproduces by seeds and vegetatively.
Evolution and Systematics
The leaves of the Venus flytrap plant close within milliseconds after the mechanical stimulation of sensitive trigger hairs.
"The rapid closure of the Venus flytrap (Dionaea muscipula) leaf in about 100 ms is one of the fastest movements in the plant kingdom. This led Darwin to describe the plant as 'one of the most wonderful in the world'1. The trap closure is initiated by the mechanical stimulation of trigger hairs. Previous studies2-7 have focused on the biochemical response of the trigger hairs to stimuli and quantified the propagation of action potentials in the leaves." (Forterre 2005:421)
Learn more about this functional adaptation.
- Forterre, Yoel; Skotheim, Jan M.; Dumais, Jacques; Mahadevan, L. 2005. How the Venus flytrap snaps. Nature. 433(7024): 421-425.
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
Reasons: This species is a narrow endemic of the coastal plain of North and South Carolina, and has very stringent requirements for frequent natural fire and an open understory. It continues to experience some collection from wild populations, though most people familiar with this species identify habitat conversion and fire suppression as the largest threats to this species.
IUCN Red List Assessment
Red List Category
Red List Criteria
- Needs updating
Global Short Term Trend: Decline of 10-30%
Comments: The species is declining in its native range (Amoroso pers. comm., Pittman pers. comm., Schafale pers. comm., Russo 1993). It is reported to be doing well in some managed gameland areas in North Carolina where prescribed fire maintains an open understory (Amoroso pers. comm.). It is declining in the Green Swamp due to fire suppression (Amoroso pers. comm.). Given the right conditions, this plant can be aggressive and weedy (Amoroso pers. comm.). This species is also apparently expanding where it has been artificially introduced in Florida (Amoroso pers. comm.). The status of introduced populations in New Jersey is unknown. Surveys by Marj Boyer of the Plant Conservation Program indicated that site occupancy declined by 10% from 1981 to 1993 (Russo 1993). Very little information is available on abundance trends for this species. It is possible that collection has significantly reduced one of the largest populations at Holly Shelter (Schafale pers. comm.).
Comments: Habitat conversion/destruction for forestry or development, and fire suppression are serious, urgent conservation concerns for this species (Frost pers. comm.) -- much more so than collection from wild populations (Amoroso pers. comm., Schafale pers. comm., Pittman pers. comm., Weakley 1996).
Occurrence numbers and sizes continue to decline primarily due to drastic changes in Dionaea's habitat as a result of fire suppression and conversion to agriculture, silviculture, and residential or commercial development which may involve logging, bedding, ditching, and draining. Fire suppression leads to shrub and tree encroachment and a gradual decline in the quality of flytrap habitat. Clear cutting and bedding can physically destroy plants, while ditching and draining can make the soil too dry for moisture-dependent flytraps. Many lesser quality, roadside occurrences of flytraps are threatened by vehicular activities, road maintenance, and road expansions.
Another major threat to flytraps is over-collection. In 1980, it was estimated that between one and four million plants were being sold each year, the majority believed removed from private and public lands in North and South Carolina (Sutter et al. 1982). Demand for flytraps continues strong, especially in Germany, Holland, and Japan, and continues to put collecting pressure on wild populations. The great majority of flytrap sellers still grow their plants from bulbs and cuttings taking from wild plants (Stolzenburg 1993). In 1994, 2,800 wild Dionaea muscipula plants were exported to Canada. There were no reported exports of wild D. muscipula in 1995 or 1996.
There is evidence from reliable sources that wild-collecting for the plant trade is occurring from many populations rangewide. Kral (1983) noted that "This is one of the most exploited of southeastern plants, large populations being decimated or exterminated for the novelty plant trade." It is difficult to say to what degree this continues to be a problem (Amoroso pers. comm.). It is possible that collection has significantly reduced one of the largest populations at Holly Shelter (Schafale pers. comm.).
A recent conviction of a Dutch citizen for collection and attempted smuggling of 8,000 live plants led to a $2,000 fine and 18 months' probation (The Washington Post, April 26, 1997).
A person knowledgable about the herbal medicinal trade says that the plant receives little use and is reportedly being cultivated (M. McGuffin pers. comm.).
Biological Research Needs: Much biological research was done by Roberts and Oosting (1958); therefore, there are no immediately pressing needs for research at this time with regard to its biology and ecology. However, the development of cost-effective and successful nursery reproduction techniques would help eliminate the need to collect wild plants (LeBlond 1993). Such techniques appear to be available now. One horticulturist in Raleigh, North Carolina, ships up to 15,000 nursery-grown plants per week to domestic and international markets (Stolzenburg 1993). However, the great majority of flytrap sellers still grow their plants from bulbs and cuttings taking from wild plants (Stolzenburg 1993).
Given the very low nutrient level of soils supporting this species, it may be necessary to establish the extent to which nitrogen and phosphorus deposition from nearby agricultural sources affects the long-term stability of this species. Changes in nutrient input may lead to unpredicted changes in the competitive interactions of co-occurring species, so that this species is at a relative disadvantage. [JRB]
Relevance to Humans and Ecosystems
Uses: MEDICINE/DRUG, ESTHETIC
Production Methods: Cultivated, Wild-harvested
Comments: The plant is easily propagated in nurseries and greenhouses. Such reproduction methods for commercial purposes should be encouraged and field collection stopped (Cooper 1977).
Prices for this species were found as follows:
North Carolina, botanical garden: $5-7/whole plant, $2/pack of seeds
U.S., internet: $24.50/fluid oz. (from organically grown cultivation) [JRB]
The Venus flytrap (also Venus's flytrap or Venus' flytrap), Dionaea muscipula, is a carnivorous plant native to subtropical wetlands on the East Coast of the United States. It catches its prey—chiefly insects and arachnids— with a trapping structure formed by the terminal portion of each of the plant's leaves and is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap closes if a different hair is contacted within twenty seconds of the first strike. The requirement of redundant triggering in this mechanism serves as a safeguard against a waste of energy in trapping objects with no nutritional value.
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 7 leaves are colonies formed by rosettes that have divided beneath the ground.
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 trapping mechanism is so 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 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 probably homologous with the tentacles found in this plant’s close relatives, the sundews.) Scientists have concluded that the Venus flytrap is closely related to Drosera (sundews), and 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 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 Nepenthes, Cephalotus, most Heliamphora, and some Drosera.
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).
When grown from seed, plants take around four to five years to reach maturity and will live for 20 to 30 years if cultivated in the right conditions.
The plant's common name refers to Venus, the Roman goddess of love. The genus name, Dionaea ("daughter of Dione"), refers to the Greek goddess Aphrodite, while the species name, muscipula is Latin for "mousetrap".
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 form of Drosera (carnivorous plants that use a sticky trap instead of a snap trap) the reason for this evolutionary branching becomes clear. Whilst Drosera consume smaller, aerial insects, Dionaea consume larger terrestrial bugs. From these larger bugs, Dionaea are able to extract more nutrients. This gives Dionaea an evolutionary advantage over their ancestral sticky trap form.
Mechanism of trapping
The mechanism by which the trap snaps shut involves a complex interaction between elasticity, turgor and growth. 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. 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. Digestion is catalysed by enzymes secreted by glands in the lobes.
Oxidative protein modification is likely to be a predigestive mechanism of the 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. Plumbagin is known to induce apoptosis, associated with the regulation of Bcl-2 family of proteins. When the Dionaea extracts were preincubated with diaphorases and NADH in the presence of serum albumin (SA), subsequent tryptic digestion of SA was facilitated. Since the secretory glands of Droseraceae contain proteases and possibly other degradative enzymes, it may be that the presence of oxygen-activating redox cofactors function as extracellular predigestive oxidants to render membrane-bound proteins of the prey (insects) more susceptible to proteolytic attacks.
The carnivorous diet is a very specialized form of foliar feeding, and is an adaptation found in several plants from soil poor in nutrients. Their carnivorous traps were evolutionarily selected to allow these organisms to survive their harsh environments.
The "snap trap" mechanism so characteristic of Dionaea is shared with only one carnivorous plant genus, Aldrovanda. This relationship was thought to be coincidental, more precisely convergent evolution, for most of the 20th century - some phylogenetic studies even suggested that the closest living relative of Aldrovanda was the sundew. It was not until 2002 that a molecular evolutionary study conducted by Ken Cameron, from the University of Wisconsin, indicated that Dionaea and Aldrovanda did in fact share a most recent common ancestor by analysis of combined nuclear and chloroplast DNA sequences.
Another study, this time appearing in the New Phytologist, presented evidence for the evolution of snap traps of Dionaea and Aldrovanda from a flypaper trap like D. regia, based on molecular data. The molecular and physiological data implies that Dionaea and Aldrovanda snap traps evolved from the flypaper traps of a common ancestor with the Drosera; the living evidence of a link between Drosera and Dionaea is D. regia and its remnant characteristics.
In this evolutionary model, pre-adaptations to evolution into snap-traps were identified in several species of Drosera, such as rapid leaf and tentacle movement. The model proposes that plant carnivory by snap-trap evolved from the flypaper traps driven by increasing prey size. Bigger prey provides increasingly higher nutritional value, but large insects can easily escape the sticky mucilage of flypaper traps; the evolution of snap-traps would prevent escape and kleptoparasitism (theft of prey captured by the plant before it can derive any benefit from it), and would also permit a more complete digestion.
Proposed evolutionary history
Carnivorous plants are generally herbs, and their traps primary growth. They generally do not form readily fossilizable structures such as thick bark or wood. As such, there's no fossil evidence of the steps that would link Dionaea and Aldrovanda, or with their common ancestor with Drosera. Despite that, it's possible to extrapolate an evolutionary history based on phylogenetic studies of both genera. So, the researchers 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 Drosera falconeri, must have adapted to move the trap and its stalks in directions that maximized its chance of capturing and retaining such prey - in this particular case, longitudinally. Once adequately "wrapped", escape would be more difficult.
- Then, evolutionary pressure selected the plants with shorter response time, in a manner similar to Drosera burmannii or Drosera glanduligera. The faster the closing, less reliant on the flypaper model the plant would be.
- As the trap became more and more active, the energy demanded to "wrap" the prey increased. Therefore, plants that could somehow differentiate between actual insects and random detritus/rain droplets would be in advantage, thus explaining the specialization of inner tentacles into trigger hairs.
- Ultimately, as the plant relied more in closing around the insect rather than gluing them, the tentacles so evident in Drosera would lose its original function altogether, becoming the "teeth" and trigger hairs — an example of natural selection hijacking pre-existing structures for new functions.
- Completing the transition, at some point in its evolutionary history the plant developed the depressed digestive glands found inside the trap, rather than using the dews in the stalks, further differentiating it from the Drosera genus.
The Venus flytrap is found in nitrogen- and phosphorus-poor environments, such as bogs and wet savannahs. Small in stature and slow growing, the 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 found natively only in 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 Florida as well as an introduced population in western Washington. The nutritional poverty of the soil is the reason that the plant relies on such elaborate traps: insect prey provide the nitrogen for protein formation that the soil cannot. The Venus flytrap is not a tropical plant and can tolerate mild winters. In fact, Venus flytraps that do not go through a period of winter dormancy will weaken and die after a period of time.
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 stem early (2–3 inches), as flowering consumes some of the plant's energy, and reduces the rate of trap production. If healthy plants are allowed to flower, successful pollination will result in the production of dozens of small, shiny black seeds.
Plants can be propagated by seed, although seedlings take several years to mature. More commonly, they are propagated by division in spring or summer.
Venus flytraps are by far the most commonly recognized and cultivated carnivorous plant. They are sold as houseplants and are often found at florists, hardware stores and supermarkets. During the past ten years or so large quantities of cultivars (cultivated varieties) have come into the market through tissue culture of selected genetic mutations. It is through tissue culture that great quantities of plants are raised for commercial markets.
Currently, there are estimated to be more than 3–6 million plants in cultivation compared to only 35,800 plants remaining in nature. Several prominent plant conservationists suggest that the plant be labeled as Vulnerable. Precise data on the distribution of population sizes in 1992 from the Office of Plant Protection suggests a more dire state for the species. Every size class in red is slated for eventual extinction with the green ones persisting longer. Smaller populations may go extinct for stochastic reasons and, since small population are more numerous in nature now and contribute more to the total number of plants remaining in the species, most of this unique and remarkable carnivorous plant species may be going extinct soon. Note that the figure of 35,800 plants in 1992 is over 20 years old and may not accurately reflect the current situation.
In alternative medicine
Venus flytrap extract is available on the market as herbal remedy, sometimes as the prime ingredient of a patent medicine named "Carnivora". According to the American Cancer Society, these products are promoted in alternative medicine as a treatment for a variety of human ailments including HIV, Crohn's disease and skin cancer, but "available scientific evidence does not support the health claims made for Venus flytrap extract".
- Schnell, D., Catling, P., Folkerts, G., Frost, C., Gardner, R., et al. (2000). Dionaea muscipula. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Listed as Vulnerable (VU A1acd, B1+2c v2.3)
- Schlauer, J. (N.d.) Dionaea muscipula. Carnivorous Plant Database.
- "Venus flytraps". The Carnivorous Plant FAQ. Retrieved 2005-06-13.
- Raven, Peter H.; Evert, Ray Franklin; Eichhorn, Susan E. (2005). Biology of Plants (7th ed.). W.H. Freeman and Company. ISBN 0-7167-1007-2.
- Forterre, Yoël; Skotheim, Jan M.; Dumais, Jacques; Mahadevan, L. (27 January 2005). "How the Venus flytrap snaps" (PDF). Nature 433 (7024): 421–425. doi:10.1038/nature03185. PMID 15674293.[dead link]
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Names and Taxonomy
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