Venus Flytrap
| Venus Flytrap | ||||||||||||
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Venus Flytrap ( Dionaea muscipula ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Dionaea | ||||||||||||
| Sol. ex J. Ellis | ||||||||||||
| Scientific name of the species | ||||||||||||
| Dionaea muscipula | ||||||||||||
| Sol. ex J. Ellis |
The Venus flytrap ( Dionaea muscipula ) is a carnivorous plant from the sundew family (Droseraceae). The species, which only occurs in a very limited range in the USA , was first described in 1768. Their fast-moving traps , like a trapping iron , are striking .
description
The Venus flytrap is a perennial , herbaceous plant . It is slow-growing and only reaches flowering maturity after three to four years . In autumn the plant stops its activity and goes into hibernation, recognizable by the formation of very small leaves with tiny, inactive traps. In spring the conditionally hardy (minimum −5 ° C, in individual cases −10 ° C low temperature) plant sprouts again. It has 5–10 leaves in a rosette, they are shaped like traps.
Roots and rhizome
The main root of the Venus flytrap dies in favor of some fibrous side roots soon after germination . The root system is mainly used to anchor the plant in the ground and to absorb water; the roots are almost irrelevant for the supply of minerals.
About 10 to 15 centimeters below the surface of the earth is the rhizome (root stock) of the plant, from which it sprouts again when destroyed above ground.
Leaves fall
The Venus flytrap is an extraordinary plant that, when irritated, can fold its elaborately constructed catch leaf extremely quickly to catch insects (especially flies and ants ) and spiders . The catch mechanism is one of the fastest known movements in the plant kingdom with a duration of up to 100 milliseconds.
The catch leaves consist of a strongly widened petiole, which can be up to ten centimeters long, and the leaf blade itself, which is very red on the inside when exposed to sunlight , is almost circular and up to five centimeters in diameter. This color and the liquid excreted by nectaries on the leaf blade serve to attract the prey. As a bud, the leaf blade, which is still closed and folded inwards at its edges, is still folded onto the very short petiole, only when this is largely fully grown does the blade fold up and open. The edges of the leaf blade are covered with pointed bristles (the marginal bristles) and marked with a UV pattern that makes the edge appear darker in the eyes of an insect than the center of the two leaf halves, where there are three to nine hair-thin bristles each (the Feeler bristles). The latter have a taper directly above their base, which acts as a joint and behind which there is a receptor cell in the leaf tissue , also at the base of the bristles. The joint not only favors the stimulus of the receptor cell, but also enables the bristle to “fold away” when the trap is closed.
If a potential prey touches one or several feeler bristles twice within 20 seconds, an action potential is triggered, which propagates over the entire leaf at a nerve-like high speed (6 to 20 cm / s) and initiates the closure. The halves of the trap's blades strike together like traps and surprise the victim.
For a long time it was discussed how the actual shutter is triggered. An explanation based on the rapid release of cell fluid was favored. In 2004, however, the mechanism was experimentally proven: In the open state, the leaf halves are convexly curved, this is done by contracting the outside of the leaf halves across the joint by around 10%. In this tensioned state, the trap waits for the trigger signal. By as yet unknown physiological processes caused by this slight change in curvature, whereupon the case abruptly from convex to concave turns form (similar to a snap-acting contact lens) and as a strained leghold traps collapses. The trap is not actively closed, but rather a previously tensioned leaf spring , like the spring of a cracking frog , relaxes after it is released.
However, this closure is not yet complete. Larger insects are trapped by the long bristles and it is impossible for them to escape. However, if the prey is far too small, it can get into the open between the bristles, which are still slightly open, and the plant spares itself time-consuming digestive processes that have no relation to the yield. Furthermore, after closing, chemical and movement receptors check whether the captured prey is actually usable. Only when they have passed on a corresponding stimulus, the trap is completely closed, otherwise it opens again after a few hours to a day and the dead prey falls to the ground. Here it is broken down and the nutrients are absorbed through the roots. This exploitation of the prey makes up the main part of the energy supply. If, however, well-digestible prey has been caught, the seal is subsequently strengthened by growth in order to completely seal the trap and prevent any leakage of fluid during the subsequent digestion. This growth can cause the trap to enlarge by up to 10% after digestion.
A digestive secretion containing amylases , esterases , phosphatases , proteases , ribonucleases and, in small traces, chitinases is now excreted from small, sedentary glands . The plants digest the trapped insects and absorb the dissolved nutrients through cells; what remains are undigested remains such as chitin armor and legs.
Digestion can take up to ten days, depending on the size of the prey, then the trap opens again and is ready for use again after the indigestible remains have been removed by rain or wind. A trap closes a maximum of seven times, then the leaf with the trap dies.
blossoms
The plant forms a stem up to 30 centimeters high in spring, which prevents pollinators from getting into the traps and being digested. The main pollinators are the hoverflies Trichodes apivorus, Typocerus sinuatus and Augochlorella gratiosa. This stem bears several white radial , hermaphrodite flowers that are five-fold and have a diameter of up to three centimeters. Each flower has five greenish sepals ( sepals ) and five non-overlapping, white petals ( petals ). The plant is dichogamous . When the flower opens, the stigma is not ready to take in pollen. The scar is frayed when it is ripe.
Fruit and seeds
The plants are not always self-fertilizing and the seed pods that form contain numerous fine, black seeds. The seeds are light and cold germinating .
Chromosome number
The number of chromosomes is 2n = 33.
Distribution area
The plant is exclusively in the Pocosin -Mooren the American states of North and South Carolina home, within a radius of about 100 kilometers around the city of Wilmington . It is naturalized in northwest Florida .
habitat
The Venus flytrap grows in permanently moist, sunny and open locations on nutrient-poor, sandy soil at temperatures that can reach -10 ° C in winter and up to 40 ° C in summer. In the summer there are regular bushfires which destroy the plant above ground. However, it then drives out of the rhizome again and finds ideal conditions in the vegetation cleared by the fire. A prolonged absence of the fires leads to the overgrowth of the Venus flytrap by the surrounding vegetation and ultimately to its death due to lack of light.
Endangerment and Status
The existence of the Venus flytrap was endangered for a long time, on the one hand by the destruction of its habitat (drainage for building purposes), but above all by commercial collections from the 1950s to the 1970s. Only with the protection by the North Carolina Plant Protection and Conservation Act and the subsequent worldwide mass production of the plant in laboratories could the collective pressure be removed from the species. Today the plant enjoys the special status of a Special Concern Not Endangered or Threatened Plant Species (in German roughly: Unendangered and non-endangered plant species of special importance), it is also protected internationally, since 1992 worldwide by the Washington Convention on the Protection of Species (Appendix II), since 1997 in the EU by EC Reg. 338/97, in 2000 the species was put on the Red List as a Vulnerable by the IUCN . Although this protection prevents the collections from flaring up again, the number of plants continues to decline due to the unchanged settlement pressure and the fight against bushfires.
The Carolina Beach State Park was founded south of Wilmington as early as 1969 , with a special focus on the carnivore species indigenous to the area.In addition to sundew , butterflies , pitcher plants and water hoses , special attention is paid to the Venus flytrap.
Systematics
The genus Dionaea is monotypical , that is, it contains only one species, Dionaea muscipula . No subspecies or varieties of the Venus flytrap have been defined. It is considered to be the most basal species within the sundew plants; their closest relatives are the king sundew ( Drosera regia ) and the water trap ( Aldrovanda vesiculosa ).
Botanical history
The plant was first mentioned on April 2, 1759, in a letter from then Governor of North Carolina , Arthur Dobbs , to the botanist Peter Collinson , a member of the Royal Society, in London. Collinson asked for seeds or live plants several times, but it wasn't until 1768 that William Young brought plants and seeds to England, where they were finally made available to Collinson and Daniel Solander (although Collinson died before he could see them). Solander named the plant Dionaea crinita , and when one of its specimens first bloomed in August 1768, he made it possible for his friend John Ellis to examine the plant. On September 1, 1768, the description of the plant, now called Dionaea muscipula by Ellis, appeared in St. James's Chronicle .
The botanical name Dionaea muscipula is probably a play on words. The generic name Dionaea refers to Dione , the mother of Venus , which is obviously an allusion to the optical similarity of the catch leaves with the human vulva ; however, the epithet muscipula literally means mousetrap. Against a conceivable spelling error ( mus ci pula = mousetrap, mus cici pula = flytrap ), the fact that Ellis was already clear about the meaning of the term in the first description, not for nothing in the English-speaking world was called " Aphrodite's Mousetrap ".
A letter with which Ellis presented the plant to Carl von Linné , accompanied by a sketch and plant material as well as initial references to the carnivory , was rejected by Ellis . Although he recognized description and drawing, he rejected the idea of carnivory with reference to Genesis 1 : 29f., According to which plants should serve humans and animals as food, but not the other way around. The assumption of carnivory is therefore blasphemous.
It was only Charles Darwin who broke this dogma in his book Insectivorous Plants , published in 1875 . In this work he also considered the Venus flytrap and demonstrated its carnivory.
Cultural history
The spectacular shape and the unusual hunting method of the plant preoccupied people early on after its description. Thomas Jefferson and Empress Joséphine already cultivated specimens of the plant. In 1800 there was a depiction of her on a dessert plate of the Königliche Porzellan-Manufaktur Berlin .
In the twentieth century, the Venus Flytrap 1960 witnessed Roger Corman's film Little Shop of Horrors (in the original: Little Shop of Horrors ) an enormous increase its reputation and became a part of popular culture; Since then, the film has served as a template for numerous new productions, including the musical The Little Horror Shop and a stage play.
Since then, depictions of Venus flytraps or characters based on them have been found in numerous films, comics, video games or as toys, but also on motif stamps, clothing, sunglasses, tableware and even as the namesake for techno pieces ( Venus Fly Trap on Storm The Funk by Too Funk , 1995).
Registered Cultivars
Venus flytraps are the most cultivated carnivores of all, they are popular ornamental plants and even available in hardware stores or supermarkets. Although the genus is monotypical, intensive breeding has resulted in numerous cultivars in recent decades . Currently there are 121 cultivars registered with the International Carnivorous Plant Society , the international registry for cultivars (ICRA):
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An unofficial list, however, has many more varieties:
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literature
- Wilhelm Barthlott, Stefan Porembski, Rüdiger Seine, Inge Theisen: Carnivores. Biology and culture of carnivorous plants . Eugen Ulmer, Stuttgart (Hohenheim) 2004, ISBN 3-8001-4144-2 .
- Ludwig Diels : Droseraceae (= The Plant Kingdom . 26 = 4, 112, ZDB -ID 846151-x ). Engelmann, Leipzig 1906, pp. 109–112.
- Peter Sitte , Elmar Weiler , Joachim W. Kadereit , Andreas Bresinsky , Christian Körner : Textbook of botany for universities . Founded by Eduard Strasburger . 35th edition. Spektrum Akademischer Verlag, Heidelberg 2002, ISBN 3-8274-1010-X .
- Extensive information on Carnivorous Plants.com by Makoto Honda (English)
- Gergo Palfalvi et al .: Genomes of the Venus Flytrap and Close Relatives Unveil the Roots of Plant Carnivory. In: Current Biology. Online publication (open access) from May 14, 2020, doi: 10.1016 / j.cub.2020.04.051 .
Individual evidence
- ↑ a b Yoël Forterre, Jan M. Skotheim, Jacques Dumais, Lakshminarayanan Mahadevan: How the Venus flytrap snaps. In: Nature . Vol. 433, No. 7024, 2005, pp. 421-425, doi : 10.1038 / nature03185 .
- ↑ Yoel Forterre, Jan Skotheim, Jacques Dumais, Lakshminarayanan Mahadevan: Mechanics of Venus' flytrap Closure. In: Witold Gutkowski, Tomasz A. Kowalewski (Ed.): 21st International Congress of Theoretical and Applied Mechanics. August 15-21, 2004, Warsaw, Poland. Proceedings. Instytut Podstawowych Problemów Techniki PAN, Warsaw 2004, ISBN 83-89687-01-1 ( digital copy (PDF; 302 KB) ).
- ^ Dionaea muscipula at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ To the Florida deposits (English)
- ↑ Fernando Rivadavia, Katsuhiko Kondo, Masahiro Kato, Mitsuyasu Hasebe: Phylogeny of the sundews, Drosera (Droseraceae), based on chloroplast rbcL and nuclear 18S ribosomal DNA sequences. In: American Journal of Botany. Vol. 90, No. 1, 2003, ISSN 0002-9122 , pp. 123-130, doi : 10.3732 / ajb.90.1.123 .
- ^ E. Charles Nelson, Daniel L. McKinley: Aphrodite's Mousetrap . A biography of Venus's Flytrap with facsimiles of and original pamphlet and the manuscripts of John Ellis. Boethius Press, Aberystwyth 1990, ISBN 0-86314-176-5 .
- ↑ International Carnivorous Plant Society CP Names Database. Retrieved on August 14, 2018 .
- ↑ List of varieties ( Memento of the original from March 25, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English)
Web links
- Dionaea muscipula inthe IUCN 2013 Red List of Threatened Species . Posted by: Schnell, D., Catling, P., Folkerts, G., Frost, C., Gardner, R., 2000. Retrieved September 14, 2013.
- Spektrum .de: Carnivorous plant works with gas radicals November 13, 2018
- SciTechDaily: How Venus Flytraps Snap: Sophisticated Trapping Mechanism Revealed in New Research from July 10, 2020, Source: University of Zurich
