The Venus flytrap is one of more than 500 species of carnivorous, or meat-eating plants. It is native to the coastal regions of North and South Carolina, where it thrives in damp, boggy areas. These are perennial plants, which means they bloom year after year. Their flowers are white with green veins running from the base of the petal toward the edges, according to the National Wildlife Federation, it is estimated that Venus flytraps can live up to 20 years or longer. Because these plants are so intriguing, many people also grow them indoors as house plants. Charles Darwin wrote in his 1875 publication, "Insectivorous Plants," that the Venus flytrap is "one of the most wonderful [plants] in the world." There's no doubt that this opinion was formed after watching the jaws of this plant snap around an insect, capturing it for a meal.
Venus flytrap is a monotypic genus closely related to the waterwheel plant (Aldrovanda vesiculosa) and sundews (Drosera), all of which belong to the family Droseraceae.
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Description of the Venus Fytrap
In terms of size, Venus flytraps grow to around 5 inches (13 centimetres) in diameter. Each plant usually has about six stems with hinged leaves. The edges of the leaves are lined with "teeth," and the leaves fit together like a clamshell. When the leaves snap shut, they form a trap. An individual trap grows to around 1 inch (3 cm), according to The International Carnivorous Plant Society. 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 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 the flytrap's "mouth" is closed, it is sealed air tight. That helps keep out bacteria.
Selection of Prey by the Venus Fytrap
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. Drosera consume smaller, aerial insects, whereas Dionaea consume larger terrestrial bugs. Dionaea are able to extract more nutrients from these larger bugs. This gives Dionaea an evolutionary advantage over their ancestral sticky trap form.
The Venus flytrap is one of a very small group of plants capable of rapid movement, such as Mimosa pudica, the Telegraph plant, sundews and bladderworts.
How Does Venus Fytrap Catch Its Prey ?
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 build-up 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 H+ (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. Flytraps show a clear example of memory in plants, the plant knows if its hair has been touched, and remembers that for a few seconds. The plant then recalls that accident if a second touch happens during that time frame, and closes.
The Process of Digesting Its Prey
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. Once the digestive glands in the leaf lobes have been activated, digestion is catalysed by hydrolase enzymes secreted by the glands. If an insect is too large it will stick out of the trap. This allows bacteria and moulds on the insect to thrive. Eventually the trap turns black, rots and falls off.
The trap constricts tightly around the insect and secretes digestive juices, much like those in your stomach. It dissolves the soft, inner parts of the insect, but not the tough, outer part called the exoskeleton. At the end of the digestive process, which takes from five to twelve days, the trap reabsorbs the digestive fluid and then reopens. The leftover parts of the insect, the exoskeleton, blow away in the wind or are washed away by rain. The time it takes for the trap to reopen depends on the size of the insect, temperature, the age of the trap, and the number of times it has gone through this process. If you feed a Venus flytrap something that doesn't move, e.g., a dead insect, it will not close tightly over it. You need to squeeze the trap and move the food around so it imitates the action of a live insect.
The lobe manufactures digestive juices and an antiseptic juice. This keeps the insect from decaying over the few days it is in the trap and purifies prey that it captures.
Where Does the Venus Flytrap Live?
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 native only to the coastal bogs of North and South Carolina in the United States, specifically within a 100-kilometer (60 mi) 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 Flytrap Reproduction
Venus flytraps reproduce like many other plants. When their flowers are pollinated, they create seeds. The seed mature after four to six weeks and become black and pear-shaped. These seeds are then spread and grow into new plants.
These flytraps can also reproduce asexually. The roots of the Venus flytrap will extend in the soil and create a bulb root. The new flytrap will grow from the bulb. A gardener can then separate the new plant and bulb from the parent plant by cutting the connecting roots.
Growing Venus Flytrap
The Venus flytrap is one of the easiest carnivorous plants to grow. If you wish to grow one or more, they have only a few requirements such as, wet roots, high humidity, full sunlight, and poor, acidic soil. It comes shipped to you as a bulb or rhizome. Plant it root side down so that the top of the bulb is even with the soil. A recommended soil mixture is one that contains sphagnum moss and sand. Do not add fertilizer or lime. Your plants will do better if you transplant them into new soil every few years.
In order to provide high humidity for your Venus flytrap, plant it in a terrarium or in a glass container with a small opening. An old aquarium or fish bowl make good containers for this purpose. You need to watch your terrarium in the summer because the temperature inside the glass may get too hot. Two hours in the sun may be sufficient. If your plants wilt, then they need to come out of the sun sooner. Just the opposite is true for winter. If it gets very cold in your area you may need to move your plants away from the window or cover them at night in order to keep them warm and moist. However, your Venus' Flytrap will experience a dormant period in the winter, from Thanksgiving to Valentine's Day so it needs fewer hours of daylight and cooler temperatures.
Another way is to plant it in a pot and place the pot in a larger container such as a bucket. Partially cover the top of the bucket with a piece of glass or Plexiglas. Don't cover the entire top because air needs to circulate.
If you grow your plant outside, it will get enough insects to eat. If it rains the container may fill up with water but this will not hurt the plants, they can live underwater for months. If you grow your plant inside you will need to feed it insects. A couple of houseflies or small slugs per month is enough during the growing season. Do your plant a favour and do NOT feed it hamburger! Indigestion, rot may occur and usually your plant will die. Find a "just right" sized bug instead!
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 centres 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. 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.
Conservation Status
The Venus flytrap is listed as vulnerable by the International Union for Conservation of Nature's Red List of Threatened Species. These plants are vulnerable from over-harvesting and habitat destruction.
Another problem for flytraps is proper soil. Forest fires are sometimes beneficial to the understory of a forest. It can clear brush and allow more sunlight through to the understory. Since forest fires are often contained and put out by humans, the trees and brush become overgrown and the Venus flytraps don't get the light they need.
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.
Special Uses of the Venus Flytrap Plant
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, 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"