flytrap n : a trap for catching flies

The Venus Flytrap, Dionaea muscipula, is a carnivorous plant that catches and digests animal prey (mostly insects and arachnids). The trapping structure is formed by the terminal portion of each of the plant's leaves. The plant's common name refers to Venus, the Roman goddess of love, whereas the genus name refers to Dione. Dionaea is a monotypic genus closely related to the waterwheel plant and sundews.

Description

The Venus Flytrap is a small herb, forming a rosette of four to seven leaves, which arise from a short subterranean stem that is actually a bulb-like rhizome. Each leaf 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 photosynthetic 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 items stumble against 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 or one hair touched twice, The edges of the lobes are fringed by stiff hair-like protrusions or cilia, which mesh together and prevent large prey items from escaping. (These protrusions, and the trigger hairs, are probably homologous with the tentacles found in this plant’s close relatives, the sundews.) 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).

Mechanism of trapping

The Venus Flytrap is one of a very small group of plants that are capable of rapid movement, such as Mimosa, the Telegraph plant, sundews and bladderworts.

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, Exactly what this stimulation does is still debated: cells in the outer layers of the lobes and midrib may rapidly secrete protons into their cell walls, loosening them and allowing them to swell rapidly by osmosis and acid growth; 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, either or neither of these mechanisms may play a role.

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. 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, even though the trap rarely catches more than three insects in its lifetime.

Habitat

The Venus Flytrap is found in nitrogen-poor environments, such as bogs and wet savannahs, and 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 100 mile radius of Wilmington, North Carolina. One such place is North Carolina's Green Swamp. There also appears to be a naturalized species of Venus Flytraps in northern Florida as well as populations in the New Jersey Pine Barrens. According to anecdotal evidence, a well-known horticulturist dropped thousands of seeds in Florida in hopes of spreading this plant. 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.

Cultivation

Venus Flytraps are very popular as cultivated plants, although they have a large reputation for being difficult to grow. This reputation is almost exclusively due to inappropriate treatment of the plants by retailers and their consequent ill-health on purchase. However, Venus Flytraps are safely grown in pots under conditions that mimic those in their natural habitat.

Venus flytraps can be grown outside on a deck, window sill, or position in the garden that receives at least 2-4 hours of sunlight per day. In areas of lower humidity, the plant can survive with frequent watering and a drainage system to prevent fungal growth. It is also beneficial to keep it in a tray with about an inch of water to maintain higher humidity levels. Stagnant water is dangerous for the plant, so using pebbles to elevate the plant from the water is safer for the plant. Venus flytraps grow better still in a greenhouse which often leads to healthy, vigorous and colourful plants. The colour of the trap leaves may be used as an indicator of sufficient light; in appropriate conditions the inside of each trap should be bright red in colour for most varieties. Insufficient light leads to the inside of the trap turning light green, although studies have shown other factors can contribute to the lack of red pigmentation. Low light also causes etiolation and makes plants more susceptible to diseases.

Venus flytraps are best grown in mixtures of sphagnum peat moss and/or peat often with the addition of sand, perlite or other inert salt free material. Soil pH should be in the range of 3.9 to 4.8.

Venus Flytraps ideally should not be watered with tap water as accumulated salts in tap water may kill carnivorous plants. While soft water with TDS of 100 ppm or less yields good growth, both distilled, reverse osmosis water or clean rain water are ideal. The soil should be kept constantly moist by placing the pot in a tray full of water, with the root bulb of the plant allowed to be above the level of the water at least part of the time to prevent root rot in stagnant water. There is no danger of over-watering as Venus flytraps can survive short periods of immersion underwater. The Infocom text adventure game Leather Goddesses of Phobos features a giant (mobile) flytrap which attempts to eat the player's character. The Sims 2: University features an unlockable object, the Cow Plant, which will lure non-player characters with a cake lure and eat them if not fed regularly. The Gravemind in Halo 2 resembles a large venus flytrap. The Deku Babas, Twilit Babas and Boko Babas in The Legend of Zelda all resemble venus flytraps. In Pokemon Diamond and Pearl, Carnivine's design is based on the Venus Flytrap; its Japanese name, Muskippa, is based on the scientific name muscipula. Creepshow 2 features a series of animated shorts about a young boy who purchases Giant Venus Flytrap bulbs and tricks a group of bullies into following him to where the large plant is rooted, only for them to be devoured one by one. In the computer game The Neverhood there are 2 venus flytraps in different areas of the game that Klaymen, the protagonist, needs to jump into in order to pass the level. The Plant Control powerset in City of Villains includes a Giant Flytrap pet.

30 Seconds to Mars' second album, A Beautiful Lie, includes a single called The Kill. The single's album art has a Venus flytrap in the front.

References

External links

• Images and movies of the Venus Flytrap (Dionaea muscipula) at ARKive
• How to grow a Venus flytrap
• The Carnivorous Plant FAQ
• The Mysterious Venus Flytrap
• Discovery explains how the Venus Flytrap snaps.
• How Venus Flytraps Work
• href="http://www.nybg.org/pr/carnivorous.html">http://www.nybg.org/pr/carnivorous.html Venus Flytrap evolution
• Carolina Beach State Park, "Fly trap Trail"
• Botanical Society of America, Dionaea muscipula - The Venus Flytrap
• Save The Venus Flytrap