Featured Plant: Venus Flytrap

Family / Families: Droseraceae
Name(s) and Author(s): Dionaea muscipula J. Ellis
Location: cultivated in Calgary, Alberta, Canada
Photograph Copyright: annkelliott@Flickr aka Anne Elliott

A while back I wrote about our Bog full of carnivorous plants, including the strange little Venus Flytrap, in  ” Creatures-from-the-Black-Lagoon/ “.

Last week my favorite blog, Botany Photo of the Day from the University of British Columbia in Vancouver, featured the Venus Flytrap. It linked to a video of an insect being captured by the plant. I have spent plenty of time staring at Venus Flytraps but I don’t think I ever saw one in action. It’s really fast!

Technical ridiculousness prevents me from actually getting the video up, so here is the BPotD writeup, with the link:

“Today we have an image of Dionaea muscipula, by Anne Elliott (aka annkelliott@Flickr), who also provided the photo of the Oxalis for the series. A photograph of this species showing its completed nastic movement is available via the Botany Photo of the Day Flickr Pool: see Rob Co’s photograph of Dionaea muscipula. Thank you Anne and Rob for sharing your great shots!

To finish off the series on nastic movements, I couldn’t resist including Dionaea muscipula or the Venus flytrap. This species exhibits seismonasty or thigmonasty, which is the nastic movement due to a touch stimulus (see a video: Venus flytrap capturing prey). This type of nastic movement was also highlighted in the first entry of the series on Mimosa pudica.

Dionaea muscipula is native to North Carolina and South Carolina in the USA. Populations of plants recorded in New Jersey and Florida are often considered to be exotic introductions. Due to its special qualities, Venus flytrap is also a popular houseplant.

As noted above, Venus flytrap is a carnivorous species that traps and digests insects for a source of nitrogen. The modified leaves of this species consist of an upper and lower portion. The lower portion, a flat stalk, terminates with the two-lobed upper portion (with the lobes joined by the midrib). Each lobe is lined with comb-like bristles. The red-coloured centre of the trap contains three sensitive trigger hairs (seen clearly in Anne’s image). When stimulated by touch, the trap shuts by means of electrochemical signals. The trap may take several minutes to close fully. Once closed, it will remain so for 5-7 days in order for the plant to secrete enzymes and digest the insect (see: Volkov, AG et al. 2008. Kinetics and Mechanisms of Dionaea muscipula Trap Closing. Plant Physiology. 146(2):694-702).”

There are a number of Venus Flytrap videos on youtube but the one linked above ( Venus flytrap capturing prey ) on Wikipedia is by far the best one I’ve seen.

Venus Flytraps are easy to grow at home. There are just a few things to remember since they do not grow like your average houseplant.

1.They like full sun.

2. Pot them up in sphagnum moss and sit the pot in a saucer of water. They need to be that wet, after all, they are bog plants. Don’t let them dry out. Change the water occasionally so it stays somewhat clean.

3. Don’t fertilize! A bog is a low fertility environment; that’s why the flytraps eat insects: to supplement their diet. Fertilizer will kill them!

4. Don’t feed them –they have evolved to feed themselves. Feeding will kill them.

5. Opening and closing takes a large amount of energy for the plant. If you touch it to make it close repeatedly, it will become weak and die.

6. From the Logee’s Greenhouse website: “Maintain a minimum temperature of 30°F . They prefer cool night temperatures for two months during the winter to induce a dormant period. Night temperatures in the high 30’s to low 40’s are ideal. A cool, neglected windowsill is perfect. During active growth, we keep them warm, above 60°, which speeds up growth.”

So, this is a houseplant that does well being left alone (except for water). If you are curious about other carnivorous plants or would like more information about the Flytraps, the International Carnivorous Plant Society  can tell you everything you need to know, and more.

Creatures from the Black Lagoon

Dionaea muscipula, the Venus Fly Trap

Not the Gill-Man, but almost as strange: Carnivorous Plants.

The Horridge Conservatory features a Bog Garden with a unique collection of carnivorous plants. These plants have the specialized ability to trap and digest invertebrates of various kinds, mostly insects ( although some large tropical specimens are said to be capable of digesting frogs, mice, rats, and bats….) These insect-eating beauties evolved in  environments where nutrient concentrations are low but water and sunshine are seasonally abundant, such as bogs and swamps.

Sarracenia purpurea, the Pitcher Plant

 

There are different mechanisms for insect-trapping if you’re a plant. One, used by  the Pitcher Plants, is to have a chamber full of enticing liquid for the poor bug to drown in and then be digested.  Another is to have glandular hairs on stalks with very sticky droplets on them. The Sundews use this method to capture their prey, which is then digested when the glands produce digestive enzymes. A third method is used by Venus Fly Traps, which is possibly most like the Creature: Near the crease where the two leaf  “jaws”  join there is a series of tiny hairs. If an  insect walks across these hairs, touching two or more of them in succession, the leaf will close quickly enough to prevent its escape. The  insect is then slowly digested and absorbed by the leaf.

Drosera capensis, the Cape Sundew

The Bog Garden has both native and exotic carnivorous plants. There are Sarracenias, Pitcher Plants that are native to the Southeastern US, along with many beautiful hybrid Sarracenias, in different colors and sizes. There are also Nepenthes, the tropical Pitcher Plants. Some of these are on loan from a student  here at URI — thanks, CJ! There are Butterworts (Pinguicula species), which trap insects with sticky hairs along the leaves and s-l-o-o-o-w-l-y roll the leaf around the insect and digest it. The Venus Fly Trap, Dionaea muscipula, is the only species of its genus and native to the Southeastern US. It continually flowers and re-seeds in the Bog.

Nepenthes hybrid 'Judith Finn', the Tropical Pitcher Plant

Some of the carnivorous plants are easy to grow and make interesting houseplants! Yes, you can feed them insects, but it is better not to trigger trapping mechanisms, unless you actually have food for them. Otherwise, they are expending a huge amount of physiological energy for no gain, and that will weaken them.

I enjoy observing the carnivorous plants even when they are not dining. Their unusual forms are intriguing and make them a great subject for photos and drawings. In fact, there are some beautiful botanical drawings of Pitcher Plants in our Hallway Gallery. For more information, the New England Carnivorous Plant Society, which generously donated many plants to the Conservatory Bog, has a great informative website, http://www.necps.org, AND a Carnivorous Plant Show in the fall. Happy Hunting!

Pinguicula, the Mexican Butterwort