Flexible mermaid

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Flexible mermaid
Flexible mermaid (Najas flexilis)

Flexible mermaid ( Najas flexilis )

Systematics
Monocots
Order : Frog-spoon-like (Alismatales)
Family : Frog bite family (Hydrocharitaceae)
Subfamily : Hydrilloideae
Genre : Mermaid herbs ( najas )
Type : Flexible mermaid
Scientific name
Najas flexilis
( Willd. ) Rostk. & WLESchmidt

The flexible mermaid ( Najas flexilis ) is a species of mermaid herbs ( Najas ) within the frog-bite family (Hydrocharitaceae). This aquatic plant is widespread in freshwater in the temperate areas of the northern hemisphere .

Description and phenology

Vegetative characteristics

The flexible mermaid is a deciduous, annual herbaceous plant . This completely submerged aquatic plant grows with prostrate to ascending, 5 to 30 cm long, freshly slack, flexible and richly branched stems on the lake bed, where it is often covered with mud, so that only the upper parts peek out.

The leaves stand together in pairs on the stem. The leaf base gradually merges into the leaf sheath that is not eyed. The simple leaf blade is up to 25 millimeters in length, about 0.5 in width, rarely up to 1 millimeter narrow-linear and more or less straight; they are barely visible serrated with six to twelve leaf teeth no more than 0.1 millimeter long on each side.

Generative traits and phenology

The flowering time in Central Europe is in July and August. The flexible mermaid is single sexed ( monoecious ). The inconspicuous flowers sit individually in the leaf axils. The male flowers are encased in a sac-like spathe , have a two-lobed perigone and only one seated, single-fan stamen . The female flowers have no shell. On the carpel has two scars and crossed two to standing teeth.

The smooth, yellowish to dark brown fruits when ripe are elliptical and cylindrical with a length of up to 3.5 millimeters.

The number of chromosomes is 2n = 24, less often 12.

ecology

The flexible mermaid consists of therophytes and hydrophytes .

The pollination takes place under water. The spread of the diaspores is Velcro spread.

Site conditions

The flexible mermaid is mainly found in the shallow water zone of nutrient-poor freshwater lakes . It grows on the bottom of the lake and, under favorable conditions, forms entire underwater meadows. It is a character species of the Najadetum intermediae from the Potamogetonion association.

The pointer values ​​according to Ellenberg are: light number L5 = penumbra plant; Temperature figure T6 = moderate to warmth indicator; Continental number K4 = sub-oceanic, showing temperate maritime climate; Moisture index F12 = underwater plant; Humidity change = showing no change in humidity; Reaction number R8 = weak base to base / calcium indicator; Nitrogen number: N5 = indicating moderate nitrogen abundance; Salt number S0 = not bearing salt.

distribution

The flexible mermaid is widespread in the northern hemisphere . In North America , its distribution area includes the Canadian New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec, Alberta, British Columbia , Manitoba, Saskatchewan and the US states Connecticut, Indiana, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, West Virginia, Illinois, Iowa, Minnesota, North Dakota, South Dakota, Wisconsin, Idaho, Montana, Oregon, Washington, Delaware , Kentucky , Maryland , Virginia , California and Utah . It is common in Eurasia . Little is known about the occurrence in Asia , there is evidence from Mongolia . In Europe there are localities in Ireland , Great Britain , Finland , Sweden , Norway , Denmark , Estonia , Latvia , Lithuania , Poland , in the European part of Russia , Germany , Austria and Switzerland . For some of the sites there is no more recent evidence.

Hazard and protection

Conservation status for the flexible mermaid ( Najas flexilis )
(national information for the reporting period 2007–2012 in
accordance with Article 17 of the Fauna-Flora-Habitat Directive)
EU country ATL BORON CON
Denmark
  • 
    		•  --- ---
    Estonia ---
  • 
    		•  ---
    Finland ---
  • 
    		•  ---
    Great Britain
  • 
    		•  --- ---
    Ireland
  • 
    		•  --- ---
    Latvia ---
  • 
    		•  ---
    Lithuania ---
  • 
    		•  ---
    Sweden ---
  • 
    		•
  • 
    		•
    Biogeographical regions: ATL = atlantic, BOR = boreal, CON = continental
    --- = the member state has no share in the respective biogeographical region or
    the natural range of the species in this state is not in the region
    Conservation status: green = cheap, orange = insufficient, red = bad
    In Austria there is a known recent occurrence in the alpine biogeographical region ,
    an assessment was not given by the EU state.

    The flexible mermaid is primarily endangered by water pollution (discharges, agriculture, motor boats), eutrophication , acidification and alkalization of the waters as well as the isolation of the occurrences, which is given in large areas of Europe.

    In Germany, the flexible mermaid is listed as critically endangered on the 1996 Red List and is strictly protected under the Federal Nature Conservation Act. The flexible mermaid is now considered extinct in Germany.

    The same applies to Switzerland: Here, too, the known occurrences are extinct, it is listed as extinct (EX or RE) on the Red List.

    Only one recent occurrence is known in Austria. It was discovered in 2002 in Lake Millstatt .

    In the Red List of Vascular Plants in Europe, the flexible mermaid was classified in the hazard category VU = "Vulnerable" = "vulnerable", it is therefore associated with a high risk of extinction in the wild.

    Due to the threat to which the flexible mermaid and its habitats are exposed, this species was already included in Appendix I (taking measures to achieve special protection) in 1979 in the Convention on the Conservation of European Wildlife and Wildlife and Their Natural Habitats ( Bern Convention ) of the species) and subsequently included in Annexes II and IV of the Fauna-Flora-Habitat Directive .

    The EU member states are obliged to designate protected areas for the species that are part of a coherent European network of ecological protected areas. This network must ensure the continued existence or the restoration of a favorable conservation status of the habitats of the species in their natural range (Articles 3 and 6 of the Fauna-Flora-Habitat Directive).

    For this species, a strict protection system must be established by the EU states, which prohibits, among other things, any deliberate picking, collecting, cutting, digging up or destruction of specimens in nature, both inside and outside of protected areas (Article 13 of the Fauna- Flora Habitat Directive).

    Taxonomy

    It was first published in 1798 under the name ( Basionym ) Caulinia flexilis by Carl Ludwig Willdenow in Mémoires de l'Académie Royale des Sciences et Belles-Lettres depuis l'Avénement de Fréderic Guillaume II au Thrône , p. 89, plate 1, figure 19. The new combination to Najas flexilis (Willd.) Rostk. & WLESchmidt was published in Flora Sedinensis 382 in 1824 by Friedrich Wilhelm Gottlieb Theophil Rostkovius and Wilhelm Ludwig Ewald Schmidt . Other synonyms for Najas flexilis (Willd.) Rostk. & WLESchmidt are: Fluvialis flexilis (Willd.) Pers. , Najas canadensis Michx. , Najas flexilis var. Microcarpa Nilsson , Najas flexilis var. Robusta Morong , Najas flexilis var. Congesta Farw. , Najas flexilis subsp. caespitosus Maguire , Najas caespitosus (Maguire) Reveal .

    further reading

    • U. Posluszny, R. Sattler: Floral development of Najas flexilis. In: Canad. J. Bot. , Volume 54, Issue 10, 1976, pp. 1140-1151.

    Individual evidence

    1. ↑ a b c d e f g h i j Flexible mermaid herb. In: FloraWeb.de.
    2. ↑ a b Profile on the vascular plants of Bavaria of the Botanical Information Node Bavaria .
    3. ↑ a b c d e f g h i j k C. Käsermann: Najas flexilis (WILLD.) ROSTK. & WLE SCHMIDT - Flexible mermaid herb - Najadaceae. In: Leaflets on species protection - flowering plants and ferns, BUWAL, SKEW, ZDSF & Pro Natura , 1999, pp. 204–205: full text PDF at InfoFlora .
    4. ↑ a b c d e f g h M. Simon et al., 2011: Flexible mermaid (Najas flexilis). In: Internet handbook on the species of the Habitats Directive Annex IV , Federal Agency for Nature Conservation. ( Memento of the original from December 5, 2014 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.  @1@ 2Template: Webachiv / IABot / www.ffh-anhang4.bfn.de
    5. ^ 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.  108 .
    6. ^ Najas flexilis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved July 1, 2014.
    7. ↑ a b Rafaël Govaerts (Ed.): Najas flexilis. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 22, 2020.
    8. ↑ European Topic Center on Biological Diversity, 2014: Species assessments at EU biogeographical level , as of June 15, 2014
    9. ↑ Moser, DM, Gygax, A., Bäumler, B., Wyler, N. & Palese, R. (2002): Red List of Endangered Ferns and Flowering Plants in Switzerland, published by the Federal Office for the Environment, Forests and Landscape (BUWAL ), 120 pp.
    10. ^ K. Pall: Najas flexilis (Najadaceae or Hydrocharitaceae), a Natura 2000 species - new for Austria. In: Neilreichia , Volume 6, 2011, pp. 11-26.
    11. ^ M. Bilz et al .: European Red List of Vascular Plants. , 2011, 144 pages.
    12. ↑ International Union for Conservation of Nature (2012): IUCN Red List Categories and Criteria: Version 3.1. Second edition, 38 pp. [PDF]
    13. ↑ Convention on the Conservation of European Wildlife and Natural Habitats of September 19, 1979
    14. ↑ Appendix I to the Convention on the Conservation of European Wildlife and Natural Habitats of 19 September 1979
    15. ↑ a b c Fauna-Flora-Habitat Directive (Council Directive 92/43 / EEC of May 21, 1992 on the conservation of natural habitats and wild animals and plants) in the version of January 1, 2007 (PDF)
    16. ↑ Flexible mermaid at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed July 1, 2014.

    Web links

    Commons : Bendable Mermaid ( Najas flexilis )  - Collection of images, videos and audio files