Prickly cress
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Illustration of Subularia aquatica |
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Witch cress ( Subularia aquatica ) is a species of the cruciferous family (Brassicaceae). This unusual species is found in littoral and aquatic habitats. As a common German name , "water pfriemenkresse" is also used.
description
The awl cress grows as an annual herbaceous plant and reaches heights of between 1.5 and 15 (rarely 0.5 to 23) centimeters. There is a short, thickened, underground stem axis with fibrous roots . There are only basal, upright or ascending leaves with awl and entire leaf blades that are 1 to 7 (rarely 0.5 to 10) centimeters long.
In racemose inflorescences there are usually two to twelve (one to 18) flowers . The flower stalks are 1 to 7 (rarely up to 10) millimeters long until the fruit is ripe. The flowers are only opened and cross-pollinated when the flowers grow above the surface of the water. If they are constantly under water, they remain closed and pollinate themselves. The sepals are usually 0.7 to 1 (0.5 to 1.3) millimeters long and 0.2 to 0.5 (rarely up to 0.7) millimeters, the small, white petals are 1.2 to 1.5 millimeters long and 0.2 to 0.5 millimeters wide.
The pods are usually 0.2 to 0.35 (0.15 to 0.55) millimeters × 1.2 to 2 (rarely up to 2.5) centimeters in size. The 0.8 to 1 millimeter × 0.5 to 0.8 millimeter large seeds are light brown in color.
The flowering period extends from July to October.
The number of chromosomes is 2n = 28, 30 or 36.
Systematics
The prickly cress belongs to the genus Subularia in the tribe Cardamineae in the family Brassicaceae .
The species Subularia aquatica contains two subspecies:
- Subularia aquatica L. subsp. aquatica : the fruit stalks are at an angle of 50 to 90 ° from the grape axis. The sepals fall off early. The pods are ellipsoidal. It represents the species in Europe and Asia.
- Subularia aquatica subsp. americana G.A. Mulligan & Calder : the fruit stalks are at an angle of 30 ° to 50 ° from the grape axis. The sepals remain until the fruit is ripe. The pods are broadly ellipsoidal to broadly ovate. She represents this species in North America.
Occurrence
The main occurrence in Europe is in Scandinavia , Scotland and Iceland , island-like occurrences reach south to the mountains of the Iberian Peninsula and the Balkan Peninsula. Furthermore, Subularia aquatica occurs in the marine areas of boreal and arctic North America and on the Kamchatka Peninsula .
It is a type of beach corridor of shallow, sometimes up to 50 cm deep flooded lake shores. It prefers acidic, humus- rich , oligotrophic (to dystrophic ), rather muddy sandy soils. It is a character species of Isoetetum echinosporae from the association Isoetion lacustris.
Morphologically similar species
The awl cress can be confused with many other small-tufted, aquatic plants such as species of the genus of the marsh rushes ( Eleocharis ), the water lobelia ( Lobelia dortmanna ), the sea bream ( Isoetes lacustris ), Limosella acaulis , Lilaeopsis occidentalis or Lilaea scilloides .
Importance and use
Subularia aquatica offers itself as a habitat for small animals and stabilizes the bank areas. This species is occasionally cultivated as a vegetation for aquariums .
Hazards and protective measures
Subularia aquatica is listed in the Red Lists of Germany and some of its federal states as "extinct or lost". In Switzerland, too, the species is in the “RE” category for Regionally Extinct, ie extinct in Switzerland. In the USA, the species is endangered by the states of Maine, Michigan, Minnesota and New York.
Individual evidence
- ↑ a b Subularia aquatica L. in the Red Lists of Germany. Retrieved December 13, 2010 .
- ↑ a b c Subularia aquatica L. Submersed Plants. (No longer available online.) Department of Ecology, State of Washington, archived from the original on July 30, 2010 ; accessed on December 13, 2010 (English). 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.
- ↑ a b c d e f g Ihsan Al-Shehbaz: Subularia Linnaeus : In Flora of North America Editorial Committee (ed.): Flora of North America North of Mexico . Volume 7: Magnoliophyta: Salicaceae to Brassicaceae . Oxford University Press, New York / Oxford a. a. 2010, ISBN 978-0-19-531822-7 , pp. 509 (English, limited preview in Google Book search). ( Subularia aquatica -. Online especially the subspecies is described Subularia aquatica subsp. Americana )
- ↑ a b 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. 452 .
- ↑ a b Wolfram Schultze Motel (Ed.): Illustrated flora of Central Europe. Pteridophyta, Spermatophyta . Founded by Gustav Hegi. 3rd revised and expanded edition. Volume IV. Part 1: Angiospermae: Dicotyledones 2 (Berberidaceae - Resedaceae) . Paul Parey, Berlin / Hamburg 1986, ISBN 3-489-63920-0 , p. 422–423 (reprint of the 2nd edition from 1963 with supplements).
- ↑ D. Moser, A. Gygax, B. Bäumler, N. Wyler & R. Palese: Red list of endangered species in Switzerland: fern and flowering plants . Federal Office for the Environment, Forests and Landscape, Bern; Center of the data network of the Swiss flora, Chambésy; Conservatoire et Jardin botaniques de la Ville de Genève, Chambésy, 2002, p. 101 ( Page no longer available , search in web archives: online (1194 kB)).
- ↑ Subularia aquatica L. Threatened and Endangered Information. In: NRCS - National Resources Conservation Service. USDA - US Department of Agriculture, accessed December 13, 2010 .
Web links
- Prickly cress. In: FloraWeb.de.
- Distribution map for Germany. In: Floraweb .
- Thomas Meyer: Data sheet with identification key and photos at Flora-de: Flora von Deutschland (old name of the website: Flowers in Swabia )
- Carl von Linné: Species Plantarum , 2, 1753, p. 642. (First publication)
- Botanical Society of the British Isles (Ed.): Hectad map of Subularia aquatica in GB and Ireland , 2010, ( distribution in the British Isles. )
- Subularia aquatica L. - Awlwort. In:Flora of Northern Ireland. National Museums Northern Ireland,accessed December 19, 2010.
- Subularia aquatica L. - "Sylört". with distribution maps of Scandinavia and the northern hemisphere from: Eric Hultén, Magnus Fries:Atlas of North European vascular plants, 1986,ISBN 3-87429-263-0. In:The virtuella floran. Naturhistoriska riksmuseet - The Swedish Museum of Natural History,accessed December 19, 2010(Swedish).