Large mermaid

from Wikipedia, the free encyclopedia
Large mermaid
Great mermaid (Najas marina)

Great mermaid ( Najas marina )

Systematics
Monocots
Order : Frog-spoon-like (Alismatales)
Family : Frog bite family (Hydrocharitaceae)
Subfamily : Hydrilloideae
Genre : Mermaid herbs ( najas )
Type : Large mermaid
Scientific name
Najas marina
L.

The Great Naiad ( Najas marina ), also marine Naiad or Large Nixkraut called, is a species of the genus mermaids herbs ( Najas ) within the family of hydrocharitaceae (Hydrocharitaceae). It is an underwater plant .

Description and ecology

illustration
Prickly stem
Stem with female flowers or fruit and clearly serrated leaves

The great mermaid is an annual herbaceous plant that reaches growth lengths of 10 to 50 centimeters. It has stiff, forked and fragile stems . The constantly against standing on the stems leaves are linear, 1 to 6 millimeters wide, roughly corrugated and prickly perforated.

The great mermaid is dioecious, separate sexes ( diocesan ). The flowers appearing under water are inconspicuous. The male flower, 1.7 to 3 millimeters long, consists of only one stamen . The female, 2.5 to 5.7 millimeters long flower contains a 1.2 to 1.7 millimeter long stylus that ends with a three-lobed stigma. The flowers are pollinated under water.

The reddish-brown nut fruit is egg-shaped with a length of 2.2 to 8 millimeters and a width of 1.2 to 2.5 millimeters. It is mainly spread endozoic by ducks . The large mermaid uses the digestive spread as a spreading strategy . The fruit can pass through the digestive system of ducks undamaged.

The number of chromosomes is 2n = 12, less often 14.

Occurrence

The great mermaid occurs worldwide in subtropical and temperate zones, mainly in the northern hemisphere : North America , Latin America and Eurasia .

It colonizes stagnant or slowly flowing water up to a water depth of 3 meters. Like all mermaid herbs , the great mermaid thrives in fresh water. However, it can also be found in the brackish water of the Baltic Sea in Sweden and Denmark . In the more salty North Sea, however, the great mermaid is missing. Overall, the great mermaid is rarely found and is on the decline due to water pollution . It is a character species of the Potamogetoneto-Najadetum marinae from the Potamogetonion association.

Systematics

Depending on the author, there are four subspecies and several varieties of Najas marina :

  • Najas marina subsp. arsenariensis (Maire) L.Triest : It occurs in Algeria.
  • Najas marina var. Brachycarpa Trautv. : It occurs from Central Asia to northern China.
  • Najas marina subsp. commersonii L. Trieste : It occurs in Mauritius , Réunion and Madagascar.
  • Najas marina var. Grossidentata Rendle : It occurs from northeastern China to Korea.
  • Middle mermaid ( Najas marina var. Intermedia (Wolfg. Ex Gorski) Rendle ); Syn .: Najas marina subsp. intermedia (Wolfgang ex Gorski) Casper : It occurs from the Mediterranean area to Yunnan and South Africa.
  • Najas marina L. subsp. marina : It is spread all over the world.
  • Najas marina subsp. sumatrana (WJde Wilde) L.Triest : It occurs in western Sumatra .
  • Najas marina var. Zollingeri Rendle : It only occurs in Lake Batur in Bali .

swell

Individual evidence

  1. ↑ a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas. 8th edition. Page 108. Stuttgart, Verlag Eugen Ulmer, 2001. ISBN 3-8001-3131-5
  2. ↑ a b c d e f g h i Rafaël Govaerts (Ed.): Najas marina. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 17, 2016.

Web links

Commons : Large mermaid ( Najas marina )  - album with pictures, videos and audio files