Swamp pond thread

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Swamp pond thread
Swamp pond thread (Zannichellia palustris)

Swamp pond thread ( Zannichellia palustris )

Systematics
Class : Bedecktsamer (Magnoliopsida)
Monocots
Order : Frog-spoon-like (Alismatales)
Family : Pondweed family (Potamogetonaceae)
Genre : Pond thread ( Zannichellia )
Type : Swamp pond thread
Scientific name
Zannichellia palustris
L.

The pond thread ( Zannichellia palustris ) is a species of pond thread ( Zannichellia ) within the family of the pondweed plants (Potamogetonaceae). It is a submerged aquatic plant .

description

Illustration from Flora Batava , Volume 7
Close up of the leaves
Close up of the beaten fruit

Vegetative characteristics

The marsh pond thread grows as a perennial herbaceous plant . It can also reproduce vegetatively through runners or through fragmentation. Individual separated sections are thus partly capable of surviving independently. Its stem becomes up to 50 cm long and is strongly branched, roots at the nodes, in the upper part this is flooding.

The linear foliage leaves have an open stipple sheath (axillary stipple) at the base, which is often referred to as an ochrea . The thread-like leaves are never wider than 0.5 mm and are two-line or almost opposite on the stem.

Generative characteristics

The flowering period extends from May to September. The swamp pond thread are single sexed (Monözie | monözisch); it forms both purely male and purely female flowers on a plant specimen. The very small individual flowers are always under water. The male flowers are solitary and have no envelope; they contain one or two fused stamens with sitting anthers . The female flowers have a cup-shaped, glass-like perigon , which mostly has free ovaries and shield-shaped stigmas. The stylus is about 0.5 mm long.

The seated or short-stalked stone fruits are often in pairs or five together. The solitary stone fruits are relatively small with a size of about 1 millimeter, beaked by an appendage and sickle-shaped.

ecology

The swamp pond thread is an annual, summer annual, aromatic, submerged aquatic plant . Vegetative reproduction occurs through the stems rooting at the nodes or through the rhizome creeping on the ground .

The flowers are always under water. Underwater pollination takes place. The fiber layer of the pollen sac wall has degenerated. The spherical pollen usually germinates into short threads in the anthers and “floods” through the funnel-shaped stigma of female flowers, which usually enclose four pistils in a membranous shell.

There is both a water pollination of the flowers and a water spreading of the stone fruits; they are spread out as floating or Velcro fruits. Fruit ripening is from July to October.

Occurrence

The swamp pond thread is common in the temperate and subtropical areas of the northern and southern hemispheres .

It grows in meso- to eutrophic standing or flowing waters such as lakes, ponds , rivers, streams or ditches. It is somewhat salt-tolerant and therefore also occurs on the North and Baltic Sea coasts. This type of plant can endure a certain level of pollution. It thrives in a water depth between 50 and 250 centimeters.

The marsh pond thread is rarely found in the southern federal states of Germany. In some federal states it is even on the red list of vascular plants. The swamp pond thread is the characteristic species of the plant association Zannichellietum palustris, but is also found in the association Najadetum intermediae and societies of the association Ranunculion fluitantis.

Systematics

Zannichellia palustris was first published by Carl von Linné . Giovanni (Gian) Girolamo Zannichelli (1661–1729), an Italian pharmacist and scientist in Venice, was honored with the genus Zannichellia .

About three subspecies are distinguished, which, however, differ both in terms of site conditions and vegetatively e.g. Sometimes very difficult to tell apart:

  • Zannichellia palustris subsp. major (Hartm.) Ooststr. & Reichg. (Syn .: Zannichellia major Boenn. Ex Rchb. , Zannichellia palustris var. Major Hartm. ): It occurs from Europe to Central Asia.
  • Zannichellia palustris subsp. palustris (syn .: Zannichellia palustris subsp. polycarpa (Nolte) K. Richt. According to Floraweb, however, this name is a synonym for Zannichellia palustris subsp. major ): The number of chromosomes is 2n = 24, 32 or 34. It is in the temperate and widespread in subtropical zones.
  • Zannichellia palustris subsp. pedicellata (Wahlenb. & Ros.) Arcang. : The chromosome number is 2n = 24 or 36. It occurs in the temperate zones of Eurasia and in North Africa. It is a character species of the Zannichellietum pedicellatae from the Potamogetonion association.

literature

Individual evidence

  1. ↑ Eckehart J. Jäger, Klaus Werner (Ed.): Exkursionsflora von Deutschland . Founded by Werner Rothmaler. 10th edited edition. tape 4 : Vascular Plants: Critical Volume . Elsevier, Spektrum Akademischer Verlag, Munich / Heidelberg 2005, ISBN 3-8274-1496-2 .
  2. ↑ a b c d e Rafaël Govaerts (ed.): Zannichellia palustris. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved August 17, 2016.
  3. ↑ a b c d e Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . 8th edition. Stuttgart, Verlag Eugen Ulmer, 2001. ISBN 3-8001-3131-5 , page 107.
  4. ↑ Lotte Burkhardt: Directory of eponymous plant names . Botanic Garden and Botanical Museum Berlin, Free University Berlin Berlin 2016. ISBN 978-3-946292-10-4 , page 1110. doi : 10.3372 / epolist2016

Web links

Commons : Swamp pond thread ( Zannichellia palustris )  - Album with pictures, videos and audio files