American skunk cabbage
| American skunk cabbage | ||||||||||||
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American skunk cabbage ( Lysichiton americanus ) |
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| Lysichiton americanus | ||||||||||||
| Hultén & H.St.John |
The American skunk cabbage ( Lysichiton americanus ), also known as the American giant arum , stinking willie , yellow false calla or simply stink cabbage , is a species of the genus Scheinkalla ( Lysichiton ) within the arum family (Araceae).
description
Vegetative characteristics
The American skunk cabbage grows as a deciduous, perennial herbaceous plant . As a permanent organ, it forms a vertical rhizome with a length of 30 cm or more and a diameter of 2.5 to 5 cm. The white roots are contractile.
The basal, upright, large leaves are divided into a petiole and a leaf blade. The thick petiole is 5 to 40 cm long. The simple, leathery leaf blade ends pointed to blunt, has a wedge-shaped to almost truncated base and a length of up to 70 cm. The median nerve merges into the petiole. The leaves only unfold after the flowering period.
Generative characteristics
The flowering time is from late winter to spring. The inflorescence typical of the arum family has no inflorescence stem. The inflorescences of the American skunk cabbage have a bad, indoloid odor (hence the common name), which is even noticeable on old herbarium material; With their odor, which is unpleasant for humans, they attract insects to pollinate. The inflorescence consists of the spathe (single bract ) and the spadix ( piston ). The boat-shaped spathe initially completely envelops the piston, the upper area opens wide during the flowering period, only the lower area around the piston stem remains completely closed; it wilts shortly after the individual flowers have faded. The 4 to 12 (up to 14) cm long cob is initially shorter than the spathe, but since its stalk grows 8 to 25 cm long to the point of seed maturity, the cob stands after a while beyond the spathe. A piston contains numerous small flowers. The hermaphrodite flowers are fourfold. There are four yellowish-green bracts . There are four fertile stamens . The one- or two-chamber usually ovary each chamber contains one or two ovules .
The elongated, egg-shaped fruit stands are 4 to 15 cm long and 1.5 to 4 cm in diameter. The berries each contain one to four seeds. In this way, around 300 to 650 seeds can develop on each cob. The gray-brown to red-brown seeds are (3 to) mostly 5 to 11 mm in size.
The number of chromosomes is 2n = 28.
Occurrence
The American skunk cabbage is native to the North American continent in the Aleutian Islands and in the Canadian and US states of Alaska and British Columbia , via Idaho , Montana , Oregon , Washington and California . It thrives in swamps, damp forests, along rivers and other slightly damp areas at altitudes between 0 and 1400 meters.
The American skunk cabbage is one of the few arum family (Araceae) that occur in the climate of the temperate latitudes and populates in particular swamp and wetlands on acidic soils, mainly in forests because of its shade tolerance. The American skunk cabbage is a neophyte in some areas in Europe , for example occasionally in Switzerland and Norway. It is more common in Sweden and regular in Great Britain and Ireland.
The American skunk cabbage has been settled by humans in some of the wet forests of the Taunus northwest of Frankfurt since the late 1970s, where it has established itself and multiplied strongly. In the meantime, some other sites have been found z. B. reported in the western Ruhr area, in Düsseldorf and on the Lower Elbe in the Stade area.
Skunk cabbage as an invasive plant
The American skunk cabbage spreads almost exclusively generatively, but vegetative reproduction cannot be ruled out, as this species is very capable of regeneration.
The species, impressive because of its size and conspicuous inflorescence, can densely cover large areas and displace other rare species of wet forests such as peat moss , liverwort or - to a lesser extent - orchids ( bioinvasion ). However, it grows very slowly and can live up to 80 years and a long-range spread has not been observed so far (all known occurrences come from anointing or from gardens), so that the American skunk cabbage plays a special role in the group of mostly fast-growing invasive neophytes .
Wetlands in Germany are mostly ecologically particularly sensitive areas, often even nature reserves , so that the use of herbicides is neither sensible nor legally permissible. The most effective method is therefore to completely remove the plants including the powerful rhizome . Prevention, information and reporting of occurrences to nature conservation or forest authorities help to prevent further spread.
The American skunk cabbage was added to the “List of Unwanted Species” for the European Union in 2016.
Systematics
The first description of Lysichiton americanus followed in 1931 by Eric Hultén and Harold St. John : The American species of Lysichitum in Svensk Botanisk Tidskrift , 25, S. 455th
literature
- Sue A. Thompson: Araceae in the Flora of North America , Volume 22, 2000: Lysichiton americanus - Online. (Section description, systematics and dissemination)
- Profile of the Internet manual NeoFlora at FloraWeb.
Individual evidence
- ↑ Eckehart J. Jäger, Friedrich Ebel, Peter Hanelt, Gerd K. Müller (eds.): Rothmaler - Exkursionsflora von Deutschland. Volume 5: Herbaceous ornamental and useful plants . Spectrum Academic Publishing House, Berlin Heidelberg 2008, ISBN 978-3-8274-0918-8 , p. 651 .
- ↑ Rafaël Govaerts (Ed.): Lysichiton - World Checklist of Selected Plant Families of the Royal Botanic Gardens, Kew. Last accessed on June 17, 2018.
- ↑ Distribution maps of the fern and flowering plants in Germany. Retrieved August 6, 2019 .
- ^ B. Alberternst & S. Nawrath: Lysichiton americanus Hultén & St.John new in continental Europe. Are there any chances of combating this in the early stages of naturalization? , In: Neobiota 1, 2002, pp. 91-99.
- ^ A. König & S. Nawrath: Lysichiton americanus Hultén & St.John (Araceae) in the Hochtaunus , In: Botany and nature protection in Hessen , 6, 1992, pp. 103-107.
- ↑ B. Alberternst: The giant aaron in the Taunus as an example for early detection and immediate measures at the beginning of the spread. In: Nat.schutz Biol. Diversity , XX, 2005.
- ^ R. Fuchs, H. Kutzelnigg, GB Feige: Natural Forest in Urban Agglomeration "Ruhr Area". , In: Acta Biologica Benrodis , 13, 2005, pp. 91-104.
- ↑ R. Fuchs, H. Kutzelnigg, GB Feige, P. Keil: Wild occurrences of Lysichiton americanus Hultén & St. John (Araceae) in Duisburg and Mülheim an der Ruhr. In: Tuexenia 23, 2003, pp. 373–379: changed online.
- ↑ Martin Wolfangel: Invasive alien plants - a threat to biological diversity .
- ↑ List of Invasive Alien Species of Union Concern (PDF) accessed on July 15, 2016
