Frog herb

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Frog herb
LuroniumNatans2.jpg

Frogweed ( Luronium natans )

Systematics
Class : Bedecktsamer (Magnoliopsida)
Monocots
Order : Frog-spoon-like (Alismatales)
Family : Frog-spoon family (Alismataceae)
Genre : Luronium
Type : Frog herb
Scientific name of the  genus
Luronium
Raf.
Scientific name of the  species
Luronium natans
( L. ) Raf.

The frog weed ( Luronium natans ), also called floating frog weed , is the only species of the monotypical plant genus Luronium within the family of the frog-spoon plants (Alismataceae). The frog herb has become rare in Central Europe and is under strict protection. The specific epithet natans (lat .: swimming) comes from the preferred growth locations on the banks of water - in the habitats of frogs .

description

Detail of the flower

Vegetative characteristics

The frog herb grows as a perennial herbaceous plant . The leafy stems are 10 to about 40 centimeters long. This aquatic plant grows either flooding under water or - in the case of temporary drying out or fluctuations in the water level - creeping on the ground. Roots are formed at the nodes . The leaves are linearly stretched under water, while oval, 3 to 6 centimeters long, stalked floating leaves are formed on the water surface.

Generative characteristics

The axillary flowers , which rise above the surface of the water between May and August, have the three white, rounded petals typical of the frog- spoon family (compare: common frog- spoon , common arrowhead , but also frog-bite plants such as frog-bite and crab claws ) that are one to one and a half centimeters in diameter to reach. The Blütengrund is colored yellow and six stamens and six to nine (rarely: twelve) carpels stocked. The fruit leaves are 12 to 15-Rippig and also the Griffel pointed. The green sepals are only a third as long as the petals.

The chromosome number of the species is 2n = 42.

Plant that has fallen dry

ecology

The vegetative reproduction or spreading takes place via runners , winter buds and seeds . The latter can survive for a long time in the diasporic reservoir of the soil, so that the plant can suddenly reappear after years of absence, if, for example, maintenance measures in a biotope provide suitable site conditions (compare, for example: black water ).

Occurrence

Frogweed is a plant species that is only found in Europe from the Atlantic to the sub- Atlantic . The distribution area extends from Western Europe to Moldova. In particular, France , Great Britain , the Netherlands , Germany , southern Sweden and parts of Poland are settled. In Germany, the main area of ​​distribution is in the north-western lowlands and here in particular in western Lower Saxony - specifically in the Emsland and East Frisia . In the southern heath , in the Münsterland , on the Lower Rhine as well as in southern Holstein and in a climatically somewhat “Atlantic-colored” sub-area of ​​southern Brandenburg and northeast Saxony, there is selective evidence. In Central Germany, Austria and Switzerland, however, the species does not occur.

In terms of plant sociology, it is a character species of the class Littorelletea (beach litter corridors), which also occurs in the order Potamogetonion ( spawning herb communities ). Luronium preferred are patchy pioneer stocks flat flooded, alternately wet Ufersäume at most moderately rich in nutrients (mesotrophic), bases - / calcium deficiency Still waters to moderate weak acid are, and have a humic sandy mud soil (see also: Heideweiher ).

Hazard, protection

Frogweed is a strongly declining, weak competitive species that is affected by the general eutrophication of the landscape and many bodies of water through agriculture and intensive fish pond management. The unnatural nutrient input promotes stronger-growing aquatic and marsh plants that displace the frogweed.

On the Red List of Threatened Plant Species in Germany, frogweed is classified as “critically endangered”, as is the corresponding Red List in Lower Saxony. In North Rhine-Westphalia , where the species occurs only in the north-western sandy areas, it is considered “threatened with extinction”, the same applies to Saxony.

In the Fauna-Flora-Habitat Directive of the European Union, the plant is listed in Appendix II, which means that specially protected areas must be established for existing occurrences. According to the Federal Nature Conservation Act , it is "strictly protected".

Taxonomy

A synonym for Luronium natans (L.) Raf. is Elisma natans (L.) Buchenau .

swell

literature

  • Eckhard Garve : Atlas of the endangered fern and flowering plants in Lower Saxony and Bremen. Nature conservation, landscape conservation, Lower Saxony 30 (1994). ISBN 3-922321-68-2
  • Henning Haeupler , Thomas Muer: picture atlas of the fern and flowering plants of Germany (= the fern and flowering plants of Germany. Volume 2). Published by the Federal Agency for Nature Conservation. Ulmer, Stuttgart 2000, ISBN 3-8001-3364-4 .
  • Erich Oberdorfer : Plant-sociological excursion flora . Ulmer Verlag, Stuttgart 1990 (6th edition). ISBN 3-8001-3454-3
  • Richard Pott: The plant communities in Germany. UTB for science, Ulmer Verlag, Stuttgart 1992. ISBN 3-8252-8067-5

Individual evidence

  1. ↑ a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . With the collaboration of Angelika Schwabe and Theo Müller. 8th, heavily revised and expanded edition. Eugen Ulmer, Stuttgart (Hohenheim) 2001, ISBN 3-8001-3131-5 , pp.  111 .
  2. ↑ Rafaël Govaerts (ed.): Luronium. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 19, 2016.

Web links

Commons : Frogweed  - Album with pictures, videos and audio files