Floating pondweed

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Floating pondweed
Floating pondweed (Potamogeton natans)

Floating pondweed ( Potamogeton natans )

Systematics
Class : Bedecktsamer (Magnoliopsida)
Monocots
Order : Frog-spoon-like (Alismatales)
Family : Pondweed family (Potamogetonaceae)
Genre : Spawn herbs ( Potamogeton )
Type : Floating pondweed
Scientific name
Potamogeton natans
L.

The floating pondweed ( Potamogeton natans ) is a plant species within the family of the pondweed plants (Potamogetonaceae). The aquatic plant, which is common in freshwater, is widespread in the temperate and subtropical zones worldwide.

description

Floating sheets with water-repellent properties

Vegetative characteristics

The floating pondweed is a wintering green, perennial herbaceous plant . It has a bulbous, thickened, starch- rich rhizome that crawls along the bottom of the water and is strongly rooted. The stems are 0.6 to 1.5 meters long.

This immersed and floating leaf plant has heterophyllia . The leaves are divided into petioles and simple leaf blades. The petioles of the underwater leaves are rush-shaped and angularly reduced. The initially formed stem-round diving leaves are mostly dead by the time they bloom. This is followed in late spring, around the end of April or beginning of May, the initially sometimes reddish and later mostly fresh green or brownish floating leaves. The coarse leathery leaf blades of the floating leaves are pointed-oval or round to elliptical with a length of up to 12 centimeters with two folds at the base of the blade.

Blooming stock
Spike inflorescence
Section of an inflorescence with close-up of flowers

Generative characteristics

The flowering period extends from May to August. The terminal, inconspicuous greenish, spike-like inflorescences protrude from the water for wind pollination . The flowers are four-fold with only one bloom circle. The stone fruit- like fruits are 3 to 4 mm in size, hardly keeled and contain only one seed.

The basic chromosome number is n = 26.

Possibility of confusion

The floating pondweed can only be confused with the knotweed pondweed (see pondweed ; this is rarer and occurs in boggy, acidic waters) and perhaps with the aquatic form of the water knotweed .

ecology

The floating leaves of this hydrophyte have stomata only on the upper side of the leaf, whereby water-repellent, embedded oil droplets ensure gas exchange. Due to the 1 to 2 cm long, differently colored joint of the leaf stalks of the floating leaves, they lie criss-cross on the water. The floating leaves can eventually form large carpets on bodies of water.

The inflorescences protrude out of the water for wind pollination and, after pollination , retreat into the water, where they reach seed maturity. The fruits are also spread by water birds by excreting the indigestible pieces. The swimming time of the fruits reaches up to 12 months.

Occurrence

The swimming pondweed is circumpolar in the temperate and subtropical zones of the northern hemisphere . The swimming pondweed is also found everywhere in Central Europe and is the most common species of its genus there.

Floating pondweed colonizes ponds, bays, ponds and ditches, and sometimes slow-flowing streams and is very adaptable. Even short periods of drying out of a body of water can be endured if the muddy soil is soaked through. It thrives in water depths between 50 and 600 centimeters. It is a Nymphaeion union character.

In the Allgäu Alps, it rises in Bavaria on the Speicherhaldenalpe near Balderschwang up to 1438 m and in Vorarlberg in the Körbersee near Schröcken up to 1660 m above sea level.

swell

  • Henning Haeupler, Thomas Muer: picture atlas of the fern and flowering plants of Germany . Ed .: Federal Agency for Nature Conservation (=  The fern and flowering plants of Germany . Volume 2 ). Eugen Ulmer, Stuttgart (Hohenheim) 2000, ISBN 3-8001-3364-4 . (Sections Description and Ecology)
  • Elfrune Wendelberger: Plants of the wetlands. BLV-Intensivführer, Munich 1986, ISBN 3-405-12967-2
  • Floating pondweed. In: FloraWeb.de. (Sections Description and Ecology)

Individual evidence

  1. ↑ a b c d e f g h i Floating pondweed. In: FloraWeb.de.
  2. ↑ a b c Ruprecht Düll , Herfried Kutzelnigg : Pocket dictionary of plants in Germany and neighboring countries. The most common Central European species in portrait . 7th, corrected and enlarged edition. Quelle & Meyer, Wiebelsheim 2011, ISBN 978-3-494-01424-1 .
  3. ↑ a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . 8th edition. Stuttgart, Verlag Eugen Ulmer, 2001. Page 106. ISBN 3-8001-3131-5
  4. ↑ Rafaël Govaerts (ed.): Potamogeton natans. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 16, 2016.
  5. ↑ Erhard Dörr, Wolfgang Lippert : Flora of the Allgäu and its surroundings. Volume 1, IHW, Eching 2001, ISBN 3-930167-50-6 , p. 133.

Web links

Commons : Floating pondweed ( Potamogeton natans )  - Album with pictures, videos and audio files