Ordinary water screw

from Wikipedia, the free encyclopedia
Ordinary water screw
Vallisneria spiralis.jpg

Common water screw ( Vallisneria spiralis )

Systematics
Monocots
Order : Frog-spoon-like (Alismatales)
Family : Frog bite family (Hydrocharitaceae)
Subfamily : Hydrilloideae
Genre : Vallisneria
Type : Ordinary water screw
Scientific name
Vallisneria spiralis
L.

The common water screw ( Vallisneria spiralis ), also known as screw vallisneria , is a species of the genus Vallisneria within the family of the frog-bite family (Hydrocharitaceae). This submerged aquatic plant is very widespread and is used to plant aquariums .

description

Illustration by Erasmus Darwin

Appearance and leaf

Vallisneria spiralis is an evergreen perennial herbaceous plant . It forms coarse, stalk-round, up to 10 cm long stolons . The basal , linear , ribbon-shaped leaves are up to 50 centimeters long and 1 to 1.5, rarely up to 2 centimeters wide. The seven to nine leaf veins run parallel, the leaf margin is slightly toothed to entire.

Inflorescence and flower

Vallisneria spiralis is dioeciously segregated ( diocesan ). In male plants, the inflorescence stem is 2 to 3 centimeters long and the spathe is elongated at a length of about 6 millimeters. The stalked male flowers have a diameter of about 0.5 millimeters and their unequal sepals are curved back and there are two upright stamens or they are fused into one. In the female inflorescence a 1 to 2 centimeter long spathe envelops over half of the ovary and it ends with two lobes; Their thread-like inflorescence stem is longer to about the same length as the leaves and turns in a spiral shape until the fruit is ripe. The durable sepals of the female flowers are ovate-oblong with a length of 1.5 to 4 millimeters and a width of 1 to 2 millimeters with a blunt upper end. There are scale-shaped, rudimentary petals. The ovary is 1.5 to 2.5 inches long. The three two-column stylus end in a hairy scar.

Fruit and seeds

The greenish-yellow fruits are up to 20 centimeters long and contain many seeds. The seeds are 1.5 to 3 millimeters long and spindle-shaped to cylindrical.

Chromosome number

The number of chromosomes is 2n = 16, 20, 22, 24, 30, 33 or 40.

Habitat

ecology

Vallisneria spiralis is a hydrophyte and grows as a submerged aquatic plant with flowing leaves, which is anchored in the bed of the water with fiber roots.

The common water screw shows interesting pollination , fertilization and spreading of the diaspores . When the male spathe is torn open under water, the male flowers loosen and rise to the surface of the water with the calyx closed. Here the sepals bend at the back and these hold the flower upright on the water surface as a boat-shaped carrier. The two stamens then stand over them like a sail. The pollen is cemented. The female flower is lifted up on its peduncle, which is not at all or only slightly twisted, until the upper part of the calyx protrudes out of the water in an oblique position. Since these parts are coated with wax, they cannot be wetted and their weight creates a small indentation in the surface of the water. Even with a movement of water, this part of the flower returns to the same position. The male flowers are driven by the movement of water or the wind and collect in the indentation of the surface created by the female flower. The now open anthers touch the curved back stigmas and dump the pollen. The pollen tube grows in a few hours through the style canal to the ovules . After fertilization, the inflorescence stalk contracts spirally due to uneven flank growth, so that the fruit can ripen under water under the protection of the leaf rosette. As it ripens, the peduncle rots and the seeds are exposed by rotting of the pericarp.

distribution

Vallisneria spiralis is a widespread invasive plant , its original range is unclear. They can be found from Southwest, Central, South and Southeast Europe through West Asia and the Caucasus to Central Asia , Indochina and Africa . There are sites in Algeria, Egypt, Sudan, Uganda, Iraq, Turkey, Ciscaucasia, Uzbekistan, Hungary, Switzerland, Moldova, in the European part of Russia, in Ukraine, Albania, Bulgaria, Croatia, Greece, Italy, Montenegro, Romania , France and Portugal.

Systematics

The first publication of Vallisneria spiralis was in 1753 by Carl von Linné in Species Plantarum , 2, p. 1015. Synonyms for Vallisneria spiralis L. are: Vallisneria jacquinii Savi , Vallisneria michelii Savi , Vallisneria linnet Bercht. & J.Presl , Vallisneria jacquiniana Spreng. , Vallisneria micheliana Spreng. , Vallisneria pusilla Barbieri ex Bertol. , Vallisneria aethiopica Fenzl , Vallisneria numidica Pomel . Of Vallisneria spiralis several subtaxa described, depending on the author, they are evaluated differently from synonymous to the independent type.

swell

Individual evidence

  1. ↑ Rolf Wisskirchen, Henning Haeupler: Standard list of fern and flowering plants in Germany. With chromosome atlas . Ed .: Federal Agency for Nature Conservation (=  The fern and flowering plants of Germany . Volume 1 ). Eugen Ulmer, Stuttgart (Hohenheim) 1998, ISBN 3-8001-3360-1 , p. 536 .
  2. ↑ a b Profile on the vascular plants of Bavaria of the Botanical Information Node Bavaria .
  3. ↑ a b c Vallisneria spiralis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved September 5, 2014.
  4. ↑ a b c d e Abdul Ghafoor: Flora of Pakistan , Volume 169: Hydrocharitaceae. Department of Botany, University of Karachi, Karachi 1985, p. 7: Vallisneria spiralis at Tropicos.org. In: Flora of Pakistan . Missouri Botanical Garden, St. Louis
  5. ↑ a b data sheet at InfoFlora, the national data and information center for Swiss flora .
  6. ↑ a b Vallisneria spiralis at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed August 22, 2016.
  7. ↑ Ordinary water screw. In: FloraWeb.de.
  8. ↑ Friedrich Markgraf : Hydrocharitaceae frog-bite plants . In: Gustav Hegi : Illustrated flora of Central Europe . 3rd edition, Volume I, Part 2, pages 175-196; Paul Parey Publishing House, Berlin, Hamburg, 1981. ISBN 3-489-51020-8
  9. ↑ Vallisneria spiralis in the IUCN Red List of Threatened Species 2012.2. Posted by: AK Gupta, 2011. Retrieved May 20, 2013.
  10. ^ Linnaeus scanned in at biodiversitylibrary.org in 1753 .
  11. ^ Rafaël Govaerts (ed.): Vallisneria spiralis. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 22, 2020.

literature

  • Herold Georg Wilhelm Johannes Schweickerdt : Investigations on photodinesis in Vallisneria spiralis. In: Yearbooks of Scientific Botany. Volume 68, No. 1, Borntraeger, Leipzig 1928 (1931 edition), pp. 79–134 (University publication Bonn, philological dissertation).
  • Jean Belin-Milleron, L'expression bio-sociologique de la plante. Les mythes végétaux et la méthode en philosophie des sciences. In: Actes du Vie Congrès International d'Histoire des Sciences (Amsterdam 14-21 August 1950) (Collection de travaux de l'Académie Internationale d'Histoire des Sciences, 6). Volume 2, Hermann & Cie, Paris 1953, pp. 661-666.
  • Christel Kasselmann : aquarium plants. Ulmer Verlag, Stuttgart 1995; 2nd, revised and expanded edition 1999, ISBN 3-8001-7454-5 , p. 435 ( var. Spiralis ) and 436 ( var. Denseserrulata ).

Web links

Commons : Vallisneria spiralis  - collection of images, videos and audio files