Round-leaved sundew

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Round-leaved sundew
Round-leaved sundew (Drosera rotundifolia)

Round-leaved sundew ( Drosera rotundifolia )

Systematics
Eudicotyledons
Nuclear eudicotyledons
Order : Clove-like (Caryophyllales)
Family : Sundew family (Droseraceae)
Genre : Sundew ( Drosera )
Type : Round-leaved sundew
Scientific name
Drosera rotundifolia
L.

The round-leaved sundew ( Drosera rotundifolia ), also called Himmelstau , Herrgottslöffel , Himmelslöffelkraut , Spölkrut , Brunstkraut , Bullenkraut or Widdertod , is a carnivorous plant from the genus Sundew ( Drosera ). Like all sundew species occurring in Germany, the species is protected by the Federal Species Protection Ordinance.

description

The round-leaved sundew is a perennial herbaceous hemicryptophyte . The plant appears from a winter bud, the so-called hibernacle , and forms a native rosette. After flowering, the plant goes into hibernation in early autumn when it forms a winter bud again and completely retracts its leaves. The plant's root system, which is less focused on nutrient supply than on anchoring, is weak and only reaches a few centimeters deep.

leaves

alternative description
Leaf of a round-leaved sundew with glue tentacles and quick tentacles (marginal)

The catch leaves typical of the genus are formed on 1 to 7 cm long petioles in a horizontal to upright leaf rosette . The leaves are rounded, often slightly wider than long, with a diameter of 0.5 to 1.8 cm and each covered with around 200 hair-thin reddish tentacles , which secrete a sticky secretion at the end that is used to catch insects . The tentacles on the edge are significantly longer than in the middle of the leaf. Quick tentacles are also formed. With these leaves, the round-leaved sundew mostly catches small insects such as mosquitoes or flies , but occasionally also larger insects such as butterflies or dragonflies , the latter using several leaves at the same time.

blossom

blossom

The round-leaved sundew blooms from June to August on one or two, up to 30 cm high, one-sided coils with up to 25 white, almost 1 cm large, on 2 mm long pedicels, which only open when there is sufficient sunshine. The flowers are initially mostly closed- flowered ( kleistogamous ). Only later are normal flowers formed, which are usually only open for a short time in the morning. Your pollen is in tetrads. Pollinators are small two-winged birds . The petals measure 5–6 mm, the sepals 4 mm. The bracts at the base of the flower stems (bracts) are elongated and smooth, occasionally catching bedrüste leaves appear well rounded on. This is particularly pronounced in populations in Corsica and New Guinea .

Fruit and seed and propagation

Fruit cluster

Fruit ripening is from August to October. The fruits are uneven, columnar capsules that survive the winter.

Often, through cross-pollination (self-fertilization is possible), large quantities of about 1.5 mm long, spindle-shaped, brown-black seeds are produced. The tiny seeds , weighing just 0.02 mg, have no nutrient tissue , a reduced seedling and an inflated seed coat . The seeds are also light germs and frost germs .

The seeds have only a low potential for spreading. The vegetative reproduction occurs through brood buds on dying leaves in moist moss (leaf embryony).

Chromosome number

The number of chromosomes is 2n = 20.

ecology

There is carnivory . The main purpose of animal trapping is to obtain additional nitrogen compounds on soils that are poor in nutrients. The edge of the catch leaves are covered with long-stalked glandular villi, the so-called tentacles, which can be irritated by proteins. At their tip, these deposit a viscous, shiny, fragrant drop that contains, among other things, protein-splitting enzymes and formic acid . In the middle of the leaf there are short-stalked digestive glands. Tiny insects, such as mosquitoes, are held in place by the trapping slime. After about an hour, the irritated tentacles move towards the center of the leaf through a growth movement. Finally, after about two hours, the whole leaf begins to curve in, so that other digestive glands can come into contact with the prey. The process is completed after about eight to twelve hours. After several days, digestion stops and the leaf blades flatten again. Only the chitin shell of the prey is not digested.

distribution

The round-leaved sundew occurs almost everywhere in the northern hemisphere , from Europe to Asia to North America, even in Alaska , Greenland , the Philippines and New Guinea, the plant is native. The plant needs full sun locations on wet, nutrient-poor and lime-free soils with a pH value between neutral 7 and acidic 3. Accordingly, it usually grows in bogs or wetlands , where it can be found in peat moss carpets of the bog gullies or as pioneer plants on regularly exposed peat - and find clay floors. The round-leaved sundew is a species of the class Oxycoco-Sphagnetea and occurs particularly in societies of the Sphagnion magellanici association, but also in those of the Scheuchzerio-Caricetea class. In the Allgäu Alps, it rises in the Vorarlberg part near Unterkrumbach to an altitude of 1,600 meters. In the Philippines it occurs in the province of Bukidnon of Mt Limbawon up to 1880 m.

Due to the drainage of bog areas and peat extraction, the habitat of the round-leaved sundew is increasingly disappearing.

Systematics

Single-flowered dwarf form at an altitude of approx. 1800 m in Carinthia.

At high altitudes there is occasionally a dwarf form with smaller leaves and only 1–3 flowers ( Drosera rotundifolia f. Pygmaea Saelan ex Hjelt , Drosera rotundifolia var. Gracilis Laest. Ex Hulten ). Two subspecies can be distinguished:

  • Drosera rotundifolia subsp. bracteata J. Kern & Stern : It occurs in western New Guinea and is characterized by bracts that have developed into catch leaves. She is by Lowrie and A. Fleischm. not acknowledged.
  • Drosera rotundifolia subsp. rotundifolia : It occurs in the temperate and subarctic zones of the northern hemisphere and on Mindanao .

Where the round-leaved sundew occurs together with Drosera anglica , they often hybridize to Drosera × obovata . It also hybridizes with Drosera intermedia to Drosera × eloisiana . Both hybrids are sterile. The crossing with Drosera linearis led to the development of the fertile Drosera anglica through polyploidy .

etymology

The botanical name is derived from the shape of the leaves as the German language, the epithet rotundifolia means "rundblättrig".

Common names

For the round-leaved sundew there are or existed the other German-language common names : Brochkraut ( Lower Rhine ), Bullkrut ( Mecklenburg ), Egelkraut (Entlibuch), Frickthau (Lower Rhine), Gideon ( Swabia ), Herrnlöffelkraut, Jungfernblüthe, Löffliekraut, Lopichcruit, Earlipper cabbage ( Appenzell ), Rossoli (Appenzell), Sindaw ( Silesia ), Sonnenkraut, Sundau (Silesia), Sonnenlöffel ( East Prussia ), Sundew, Spöölkrud ( East Friesland ), Widdertod, noble Wiederthon (Silesia) and güldin Widerthon.

use

The round-leaved sundew was known as "lus-na-feàrnaich" in the Scottish Highlands and was a traditional dye for the color purple .

Research history

1860 gave Charles Darwin on a heath in Sussex on occurrence of round-leaved sundew and was amazed at the large number of trapped insects. Darwin then began to examine the plant more closely with regard to a possible carnivory and carried out extensive series of tests on it over the years. Although the idea of ​​the carnivory of plants was not new, it was unanimously rejected by the botanists of the time.

With the work "Insectivorous Plants", which was available in English in 1875 and in German the following year, he proved the existence of carnivore for the round-leaved sundew and at the same time for numerous other genera and species. He broke through that of Carl Linnaeus established dogma that the Karnivorie was "against the divine order of nature."

The round-leaved sundew was voted Flower of the Year 1992 .

literature

Individual evidence

  1. ^ Siegfried RH Hartmeyer: Drosera rotundifolia Tentacle-dimorphism. December 19, 2016, accessed May 16, 2019 .
  2. ↑ Drosera rotundifolia in Flora of China @ efloras.org. Retrieved October 6, 2018 .
  3. ↑ a b c Fulgent Coritico, Andreas Fleischmann: The first record of the boreal bog species Drosera rotundifolia (Droseraceae) from the Philippines, and a key to the Philippine sundews . In: Naturalis Biodiversity Center (Ed.): Blumea journal of plant taxonomy and plant geography . tape 61 , no. 1 , January 2016, p. 24-28 ( researchgate.net ).
  4. ^ Daniel R. Campbell, Line Rochefort, Claude Lavoie: Determining the immigration potential of plants colonizing disturbed environments: the case of milled peatlands in Quebec . In: British Ecological Society (Ed.): Journal of Applied Ecology . tape 40 , 2003, p. 85 ( wiley.com ).
  5. ↑ a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas. 8th, heavily revised and expanded edition. Eugen Ulmer, Stuttgart 2001, ISBN 3-8001-3131-5 , p. 479.
  6. ↑ a b c Rafaël Govaerts (Ed.): Drosera rotundifolia. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 20, 2017.
  7. ↑ Erhard Dörr, Wolfgang Lippert : Flora of the Allgäu and its surroundings. Volume 1, IHW, Eching 2001, ISBN 3-930167-50-6 , p. 632.
  8. ↑ Rafaël Govaerts (Ed.) :: Drosera rotundifolia subsp. bracteata J. Kern & Stern, Nova Guinea, ns, 6: 279 (1955). - World Checklist of Selected Plant Families of the Royal Botanic Gardens, Kew. Retrieved October 6, 2018 .
  9. ^ Georg August Pritzel , Carl Jessen : The German folk names of plants. New contribution to the German linguistic treasure. Philipp Cohen, Hanover 1882, p. 137 f.
  10. ↑ Edward Dwelly: The Illustrated Gaelic Dictionary. Volume 2. Revised edition. Self-published, Herne Bay 1911, p. 615 .

Web links

Commons : Rundblättriger Sonnentau  - Album with pictures, videos and audio files