Venus fly trap growth

Investigating the Venus Flytrap’s Speedy Snap

(ISNS) — Plants aren’t typically known for their speed, but the carnivorous Venus flytrap can close its jaw-like leaves in the blink of an eye. Charles Darwin once referred to the Venus flytrap as “one of the most wonderful plants in the world.” But despite the plant’s notoriety, its closing mechanism remains a mystery 250 years after its discovery.
Biophysicists at the Ecole Polytechnique Universitaire de Marseille, in France, are investigating the cellular process behind the Venus flytrap’s rapid response to prey. The researchers have already thrown out one popular explanation for the Venus flytrap’s quick motion, that water movement within the plant makes its jaw snap. They announced this finding in San Diego at a meeting of the American Physical Society’s Division of Fluid Dynamics.
“This is the first time someone has looked at how Venus flytraps move on the cellular level,” said biophysicist and lead researcher Mathieu Colombani. “We are looking for an explanation that’s both biologically and physically possible.”
Venus flytraps are native to the coastal bogs of North and South Carolina. The bogs’ soil lacks the proper nutrients — particularly nitrogen and phosphorus — for plants to grow. The plant manages to survive in this tough environment by trapping and digesting insects in order to fulfill their nutritional needs.
“In these bogs you see a lot of carnivorous plants that rely on animals and insects for nutrients,” said biophysicist Jacques Dumais of the Universidad Adolfo Ibanez in Chile.
When an insect is drawn into one of the plant’s traps, it tickles a small, hair-like outgrowth on the inside of the leaf. When two different outgrowths are triggered in short succession, a rapid process triggers the leaves to shut, trapping the insect in as little as one-tenth of a second.
As the insect struggles to escape, it triggers even more outgrowths, causing the Venus flytrap to tighten its grip and release enzymes to digest its snack. Each “mouth” can only snap shut four or five times before it dies, whether it catches something or not.
In 2005, scientists discovered the large-scale principle behind the plant’s bite. Each leaf pops from convex to concave as it closes, like a jumping popper toy or an inverted contact lens.
“A Venus flytrap is like two popper toys put together,” said Colombani. “Once the process is started, the two leaves snap together very quickly.”
When the plant’s leaves are separated, the trap is in a stable equilibrium and remains open. Once the plant’s prey springs the trap, some internal process in the plant upsets the system, causing the two leaves to quickly snap together. Identifying this internal process is the focus of Colombani’s research.
“The Venus flytrap’s movements are as much a biological process as a physical process,” said Dumais. “Colombani’s work is a really wonderful attempt to understand everything from beginning to end.”
Currently there are several theories on how the Venus flytrap’s leaves become unstable.
The researchers were able to rule out one popular theory, which suggests that cells on the inside of the plant’s leaves transfer water to cells on the outside of the leaves. The resulting cell size change would alter the shape of the leaves, possibly causing them to quickly destabilize and pop together. Colombani’s team looked at the pressure change inside a single cell as the leaves snapped shut.
“It’s difficult because you need to stay focused on a single cell and the plant’s leaves move very quickly,” said Colombani.
To solve this problem, the researchers creatively used blue dental paste to glue one of the Venus flytrap’s leaves to an anchored plastic fork. This setup kept the leaf from moving and made focusing on a single cell possible. They found that the movement of water between the inner and outer cells was far too slow to be responsible for the plant’s rapid movements.
“It takes a few seconds for each cell to relax, which means that it would take about two minutes for the plant to close,” said Colombani. “This doesn’t seem like a good candidate for a mechanism that takes less than a second.”
The researchers are currently testing another popular explanation that says the elasticity of the plant’s cell walls changes, causing the leaves to destabilize and snap together. Colombani says that whatever the mechanisms behind the remarkable plant’s bite are, they could have potential applications in medicine or other fields.

Thomas Sumner is a science writer based in Santa Cruz, Calif.

Lissa Leege, a plant ecologist and assistant professor of biology at Georgia Southern University, explains.

Perhaps the best known of the insectivorous (insect-eating) plants, the Venus flytrap (Dionaea muscipula) exhibits a unique system by which it attracts, kills, digests and absorbs its prey. Because it is a plant and can make its own food through photosynthesis, the Venus flytrap does not eat and digest its prey for the traditional nonplant objectives of harvesting energy and carbon. Instead, it mines its prey primarily for essential nutrients (nitrogen and phosphorous in particular) that are in short supply in its boggy, acidic habitat. So, yes, the Venus flytrap does have a digestive system of sorts, but it serves a somewhat different purpose than an animals does.

How does a stationary organism manage to attract, kill, digest and absorb its prey? First, it lures its victim with sweet-smelling nectar, secreted on its steel-trap-shaped leaves. Unsuspecting prey land on the leaf in search of a reward but instead trip the bristly trigger hairs on the leaf and find themselves imprisoned behind the interlocking teeth of the leaf edges. There are between three and six trigger hairs on the surface of each leaf. If the same hair is touched twice or if two hairs are touched within a 20-second interval, the cells on the outer surface of the leaf expand rapidly, and the trap snaps shut instantly. If insect secretions, such as uric acid, stimulate the trap, it will clamp down further on the prey and form an airtight seal. (If tripped by a curious spectator or a falling dead twig, the trap will reopen within a day or so.) Once the trap closes, the digestive glands that line the interior edge of the leaf secrete fluids that dissolve the soft parts of the prey, kill bacteria and fungi, and break down the insect with enzymes to extract the essential nutrients. These nutrients are absorbed into the leaf, and five to 12 days following capture, the trap will reopen to release the leftover exoskeleton. After three to five meals, the trap will no longer capture prey but will spend another two to three months simply photosynthesizing before it drops off the plant. Plant owners should beware of overstimulating a Venus flytrap: after approximately 10 unsuccessful trap closures, the leaf will cease to respond to touch and will serve only as a photosynthetic organ.

The Venus flytrap occurs in a very restricted range in sandy shrub-bogs in coastal North and South Carolina, where it is listed as an endangered species. The ecosystem that supports Venus flytraps experiences frequent fires that clear out competing plants and volatilize nitrogen in the soil. Hence, Venus flytraps have a corner on the nitrogen market immediately following fire, when they obtain three quarters of their nitrogen supply from insect prey. If fire does not reoccur within 10 years, however, competition with other plants restricts the Venus flytraps access to light and insects, and populations begin to decline. Venus flytraps provide a fascinating example of how organisms adapt to stressful conditions, in this case behaving as predators to make up for the nutrient deficiencies in the surrounding soil.
Answer originally published August 19,2002.

Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), rely on nutrients from small prey animals when growing in nutrient-poor soil. When an unsuspecting prey brushes up against two touch-sensitive hairs on the inside of the trap-shaped leaves, the trap snaps shut, ensnaring the prey for later digestion.

The touch-sensitive hairs, known as trigger hairs, signal trap closure using sodium-activated action potentials (APs). An action potential is a way for cells to send information to one another in the form of an electrical signal. It occurs when positively charged ions, such as sodium, enter a cell and cause the electrical environment of the cell membrane to change until it reaches a certain threshold. After it reaches this threshold the cell “fires,” sending the electrical signal to another cell to activate a response.

In the case of the Venus flytrap, the two trigger hairs send a signal to the leaves to snap shut. Physical stimulation of one hair releases sodium ions into the hair cell, triggering the first action potential. Stimulating a second hair will release more sodium ions, triggering a second AP. Once two APs are elicited within 15-20 seconds of each other, these electrical signals stimulate motor cells in the leaves to snap the trap shut. This signal is incredibly fast, and the trap snaps shut within 100 ms of the triggering of the second hair.

Once the prey is captured it struggles to escape, continuously brushing more trigger hairs that fire more action potentials. These signals are sent to glands that line the leaves, which release enzymes to digest the prey. The prey is loaded with essential nutrients, including sodium, and its digestion provides a source of new sodium ions to trigger the next action potential to capture the plant’s next victim.

To learn more about how the Venus flytrap’s leaves power movement, check out this related strategy.

This strategy was contributed by Alexandra Ralevski.

Edit Summary

First, you need to take a deep breath and not panic! If your Venus fly trap is turning black, it’s most likely going through completely normal processes.

The main reason a trap turns black and dies is that it’s simply at the end of its lifespan. Each individual trap on a plant has a lifespan of about three months during which it will catch about 1-4 insects.

As long as green new growth is replacing the dying traps, your plant is doing fine! However there are a number of other reasons why your Venus fly trap is turning black. Read on to find out what these causes may be, and their solutions!

  • Overfeeding

It’s quite possible your plant is developing black traps if you fed every single trap on the plant. Yes, insects provide the nourishment that those traps seek, but closing every trap and digesting every single piece of food that’s inside those traps takes a huge amount of energy.

Traps may begin to die off to concentrate their remaining energy on photosynthesizing new growth. It’s also possible that the overload of nitrogen from too much food causes the traps to die. The solution to this is simply not hand-feeding your plant for about a month. Give it time to recover and maybe catch its own food.

When the new leaves are fully mature and open, you can resume feeding, but only 1-2 traps per plant once a week at the most. For more feeding advice, read my Venus fly trap food guide.

  • Eating something too big

Too big!

In order to successfully digest its food, a Venus fly trap must seal both sides of its leaves together. Sometimes an insect with long legs or large wings gets caught in the trap. If these legs or wings stick outside of the trap, it cannot fully seal and may turn black and die as a result.

When feeding your plants, remember to keep the food 1/3 the size of the trap. Unfortunately, traps will sometimes bite off more than they can chew on their own. In this situation, leaving the plant alone is the best thing to do. Again, new growth will replace the dying trap.

  • Stress from moving or repotting

Did you get a new plant within the last month or few weeks? Did you also happen to put it into a new pot? If so, your plant simply need time to adjust to its new conditions. Traps dying on a newly repotted plant is normal, and essentially expected to happen.

To minimize potting stress, wait until the end of dormancy (February or March) before repotting. Even if it’s still in the same pot, being shipped in a box or even just a ride in the car from the nursery can be stressful for a plant. Time and good care is the best cure!

  • Improper soil/water/container

Venus fly traps along with most other carnivorous plants need nutrient-poor soil. The go-to options are usually pure peat moss or New Zealand long fiber sphagnum moss. The soil should be aerated with perlite or silicia sand.

These must have no fertilizers or nutrients added, or the plant may suffer mineral burn. If you’re using regular potting soil or something with additives, take your plant out immediately!

Soak it in distilled water while you go out and buy the right ingredients.

On the subject of water, your tap water likely has a higher concentration of Total Dissolved Solids (TDS) than what most carnivorous plants can take. If water has 50 ppm (parts per million) TDS or less, then it’s safe for carnivorous plants.

Most growers (myself included) need to buy gallons of distilled water for their plants. Saved rain water is also an excellent source for your plants. If you want, you can buy a TDS Meter to check your water sources. You may be one of the lucky ones that has nearly pure tap water! Yes, I’m jealous.

Your planter could also leech minerals into the soil and be the reason your Venus fly trap is turning black. Clay, terracotta, or un-glazed ceramic pots are highly discouraged for carnivores. Because they’re porous and made from organic materials, they will add minerals to your soil over time. This is a slow process that you can hold off if you regularly flush your pot with distilled water.

For the long term, you’ll want your plants in a plastic, foam or completely glazed ceramic pot.

No terrariums! Planters should be opaque. I like these pots a lot for adult plants, and also have a stack of these handy for seedlings and smaller plants. You can also find good ones at your local dollar or thrift store. Remember they must also have drainage holes in the bottom!

  • Dormancy

As cold weather approaches, Venus fly traps may start losing more of their leaves in preparation for dormancy. Dormancy is a completely natural process that is essential for Venus fly traps to survive.

When dormant, some plants may lose all of their traps or they could have a few remaining. There won’t be much new growth until the next spring, so the only solution is to wait until then.

Dormancy sucks for every grower, but it really makes you appreciate how stunning the plants are in the summer! Consider getting an easy tropical plant like a cape sundew to combat those dormancy blues!

Still have questions about your Venus flytrap or other carnivorous plants? Enter your email below for a free FAQ on growing carnivorous plants!

Thanks for reading, and I hope you found this information useful! Good luck with your Venus flytrap and I’ll see you in the next blog post!

The Venus flytrap – also known as Dionaea muscipula – is a rare plant that eats small living creatures as prey. Insects and spiders are among its favorite foods. But how does it know when to snap shut?

If you touch a Venus flytrap with a stick, you can probably get it to shut. But your stick won’t fool the plant into completing the process of digestion.

That’s because each Venus flytrap can close only half a dozen times over the course of its lifetime – so a Venus flytrap is particular about what it decides to digest. In fact, the traps have evolved to ensure that only worthwhile prey will trigger digestion.

How does it work? The answer lies in the construction of the plant itself. Every Venus flytrap has delicate hairs on the inside of its flat leaves. These hairs have to be disturbed twice in 20 seconds in order for the plant to close. The trap closes only when an insect or spider crawling along the leaves comes into contact with one or more of the hairs twice in succession.

But even this double stimulus of the hairs on its leaves won’t ensure the process of digestion in a Venus flytrap. Once its outer leaves have closed, the Venus flytrap has to be continuously stimulated by its struggling prey for the digestive process to continue. If there is indeed live prey in the plant, the trap seals around the insect and secretes its digestive juices.

So you might be able to get a Venus flytrap to close around a piece of rubber or a rock. But the plant knows better than to spend time digesting this object.

On the other hand, if a Venus flytrap does successfully absorb its prey, digestion will proceed. In that case, the plant will be open for business again … a few days later.

Venus flytraps are rare in the U.S. In the fall of 2016, American ecologists helped get a petition filed with the U.S. Fish and Wildlife Service Friday seeking emergency Endangered Species Act protection for the Venus flytrap. These plants grow in tough living conditions – sandy, acidic soils that are wet most of the year – in long-leaf pine forests. Frequent fires in these forests act like a dose of fertilizer for these meat-eating plants.

Although Venus flytraps have always had a small geographic range, today only a small percentage of their original habitat remains. They’re found in only two U.S. states, along the coastal plains of North and South Carolina.

Scientists say the key to survival for wild Venus flytraps lies in preserving the last stands of U.S. long-leaf pine forests – and in protecting wetlands – and in prescribing fire when needed.

Experts say you can help, too. They say it’s important not to buy any wild Venus flytrap plant. Buying only those plants grown in greenhouses is the best way to help preserve Venus flytraps.

Open (convex) and closed (concave) forms of the Venus flytrap. Image via Noah Elhardt and Sanjay Acharya.

Bottom line: Every Venus flytrap has delicate hairs on the inside of its flat leaves. These hairs have to be disturbed twice in about 20 seconds in order for the plant to close.

Read more: Botanist leads petition to give Venus Flytrap endangered species protection

More about the Venus flytrap from the U.S. Department of Agriculture Plants Database.

The EarthSky team has a blast bringing you daily updates on your cosmos and world. We love your photos and welcome your news tips. Earth, Space, Human World, Tonight.

How to Grow Venus Flytrap

When I was a kid, I thought Venus flytraps really did come from Venus. Their gaping bifold jaws with spiky fringed “teeth” seemed alien enough, but when an insect landed on that enticing pink center and the trap closed with lightning speed, well, that was exciting! Growing Venus flytraps indoors seemed like a superhuman feat. Luckily, it’s not difficult if you know how to grow Venus flytrap.

Image zoom Ginny Weiler Ginny Weiler

Where Venus Flytraps Grow

Instead of originating one planet away from Earth, Venus flytraps (Dionaea muscipula) are perennials native to boggy areas of coastal North and South Carolina. They grow in moist, acidic soils in full sun, but only survive winter outdoors in Zones 8-10. Gardeners in colder-winter climates should grow Venus flytraps in a moist environment, such as a terrarium, that can go indoors during winter.

Growing Venus Flytraps

Venus flytrap care is pretty simple. The carnivorous plant thrives in poor, acidic soil with good drainage. Avoid planting it in regular potting soil: A blend of one-third sand and two-thirds sphagnum peat moss provides the best drainage and moisture retention. Do not add lime to the soil and never fertilize the plant.

Venus flytraps do best in bright light but can live in partial shade. Avoid placing them in direct sunlight in summer, especially if they live under glass, as plants hit with direct sunlight may get too hot and burn up. When grown inside under artificial lights, keep flytraps 4 to 7 inches away from fluorescent lights. If your Venus flytraps don’t show a pink interior or if the plants have long, spindly leaves, they are not getting enough sunlight.

For best Venus flytrap care, keep the environment humid and the soil moist but don’t let the plants stand constantly in water. Grow them in a pot with drainage holes. If you have a Venus flytrap terrarium, place gravel below the soil for extra drainage. Good air circulation is also important in growing Venus flytrap. Use rain or distilled water to take care of your Venus flytrap, because tap water is often too alkaline or may contain too many added minerals.

Image zoom Ginny Weiler Ginny Weiler

Feeding Venus Flytrap

What do Venus flytrap plants eat? The name says it all: The Venus flytrap eats flies (or other small insects). The prey must be alive when caught. Dead flies won’t work in Venus flytrap feeding; the insect must move around inside the trap or the trap cannot consume and digest it. The insect must be small enough to fit comfortably inside the trap so it can close tightly to keep out bacteria.

If you grow the plants in a closed terrarium, the easiest Venus flytrap feeding method is to release small flies inside the space. Eventually, the bugs will be attracted to the trap and be consumed. Although flytraps are carnivorous, they can go long periods—a month or two—without eating insects. If you grow them outdoors, they will get enough to eat naturally. If you’re growing Venus flytrap indoors, you’ll have to feed them dinner periodically.

Related: Growing Carnivorous Plants in the Garden

Winter Dormancy for Venus Flytraps

Venus flytraps, like many other plants, need a period of winter dormancy when they appear to be dead (the leaves may die back) but are merely resting. Keep the plant 35 to 50 degrees F. Don’t let terrariums freeze; the plants may die and the glass may break. At about the spring equinox, when days start growing longer, begin to increase warmth and light.

Venus Flytrap Varieties

Plant breeders have been working with Venus flytraps and have come out with a few varieties, such as ‘Akai Ryu’, which has large burgundy-red traps. These special varieties are available from specialty garden centers or online retailers, like this Red Dragon Fly Trap, $21, Plant Delights Nursery.

  • By Deb Wiley

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