Water ragwort

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Water ragwort
Water ragwort (Jacobaea aquatica)

Water ragwort ( Jacobaea aquatica )

Systematics
Order : Astern-like (Asterales)
Family : Daisy family (Asteraceae)
Subfamily : Asteroideae
Tribe : Senecioneae
Genre : Jacobaea
Type : Water ragwort
Scientific name
Jacobaea aquatica
( Hill ) G. Gaertn. & al.

The water ragwort , also water ragwort ( Jacobaea aquatica ) is a species of the genus Jacobaea within the sunflower family (Asteraceae).

Description and ecology

Illustration from Flora Batava , Volume 12
Illustration from storm

The water ragwort is an annual herbaceous plant that reaches heights of between 15 and 80 centimeters. The water ragwort is a deciduous hemicryptophyte . The plant usually only has upward side branches at the tip, which distinguishes the water ragwort from the later blooming ragwort ( Jacobaea erraticus ), whose stems branch out sparsely below the middle.

The basal sheets are partly undivided or slightly incised with more or less large end lobes. The light green stem leaves are pinnate with three to four pairs of leaflets. These are narrow-linear-lanceolate and directed upwards at an acute angle. The middle and upper stem leaves have an ovate-elongated end lobe.

The flowering period extends from June to October. The cup-shaped partial inflorescences stand together in a golden , almost leafless paniculate inflorescence . The flower heads are 20 to 30 millimeters in diameter and contain ray and tubular flowers. The flower heads have 13 bracts and up to four outer bracts. Outside is a wreath with about 13 light gold-yellow, zygomorphic ray- flowers (0 ray-flowers), which are 10 to 12 millimeters long.

The achenes are bald or the inner ones are sparsely hairy. The pappus comes off easily.

The plant usually dies after seed formation. The pollination is done by insects , particularly flies .

According to Oberdorfer, the number of chromosomes is 2n = 40.

Occurrence

The water ragwort is particularly widespread in Western and Central Europe. Individual occurrences can be found in southern, eastern and northern Europe. In New Zealand it is a neophyte. The original distribution area includes Portugal, Spain, France, Ireland, Great Britain, Denmark, Norway, Sweden, Belgium, the Netherlands, Germany, the Czech Republic, Poland, the Kaliningrad Oblast , Austria, Switzerland, Hungary, Slovenia, Croatia, Italy, Greece, Bulgaria, Romania, Estonia and Belarus. In Germany it is especially common in the north-west and south; it is much rarer in the northeast. In Germany, the species occurs from the lowlands to mid-mountain ranges and reaches altitudes of up to 866 meters in the Alps. In the Allgäu Alps, however, it rises up to 1350 meters in the Kleiner Walsertal on the Brandalpe near Riezlern below the Gottesacker area.

The water ragwort grows in Central Europe often in smaller to larger stocks in wet and humid meadows , at ditches and springs on seeping and waterlogged, lime-poor, neutral, humus-rich clay soils . According to Oberdorfer, it is a character species of the Calthion association in Central Europe and occurs locally in the Senecionetum aquaticae association.

Ingredients and toxicity

The water ragwort is a poisonous meadow "weed". It is toxic both when consumed and in contact with skin. However, according to Rauschert (1961), like rocket-leaf ragwort ( Jacobaea erucifolia ), it is somewhat less poisonous than Jacob's ragwort .

The toxic effect can be attributed to pyrrolizidine alkaloids . Horses and cattle are more sensitive to this than sheep and goats. There is a particular risk of poisoning if water-ground ragweed is contained in hay or silage and is fed to animals. By preserving the feed, the bitter substances are broken down, whereas the toxins remain, so that the animals can no longer recognize the poisonous plant as such. The effect of the toxins is cumulative, which means that even small but steadily ingested amounts can lead to liver damage and ultimately fatal poisoning. The effects of the poison on the human organism are not yet fully known. That is why foods such as milk, honey and herbs are examined for pyrrolizidine alkaloids.

Prevention and Management

For a successful precaution against the common ragwort, cutting out the first individuals and maintaining a closed sward is essential, since mass populations can only be reduced to tolerable population sizes through site-specific management. For proper grassland management, it is important not to damage the sward as much as possible (e.g. by mowing and maintenance devices that disturb the ground or driving tracks in wet conditions) and to avoid open areas of the ground (also not by left mowing residues or silage bales). The aim is to keep the stock on usable areas below a tolerance limit of less than one plant per 10 m². Trying to eradicate ragwort in typical locations is not practical. It has always been part of the ancestral inventory of wet meadows.

There is an urgent need for action on commercial grassland if the feed is used for cows or horses. An individual risk assessment is also necessary when grazing with sheep or goats. The goals of regulation are to reduce the population and seed production, prevent open ground areas, improve the meadow structure and develop a closed sward.

In all management measures, attention must be paid to possible restrictions, such as requirements for the time of cutting or fertilization on contractual nature conservation areas, the possible forms of use in protected areas or legally protected biotopes. Early mechanical processes combined with adapted use usually enable a sufficient, sustainable reduction.

Systematics

It was first published in 1761 under the name ( Basionym ) Senecio aquaticus by John Hill . The new combination to Jacobaea aquatica (Hill) G.Gaertn. & al. was published in 1801. A synonym for Jacobaea aquatica (Hill) G.Gaertn. & al. is Senecio pratensis dir.

The species Jacobaea aquatica (Hill) G.Gaertn. & al. , Jacobaea argunensis (Turcz.) B.Nord. , Jacobaea erratica (Bertol.) Fourr. , Jacobaea erucifolia (L.) G.Gaertn. & al. , Jacobaea lycopifolia (Poir.) Greuter & B.Nord. , Jacobaea ornata (Druce) Greuter & B.Nord. and Jacobaea vulgaris Gaertn. are sometimes combined as a species group: Jacobaea erucifolia agg.

Some authors differentiate between two varieties of water ragwort:

  • Jacobaea aquatica (Hill) G. Gaertn. & al. var. aquatica
  • Jacobaea aquatica (Hill) G. Gaertn. & al. var. erratica (Bertol.) Pelser & Meijden (Syn .: Jacobaea erratica (Bertol.) Fourr. , Senecio erraticus Bertol. , Senecio jacobaea L. var. barbareifolius Fiori ): It occurs in southern, central and eastern Europe, in North Africa, West Asia and the Caucasus.

literature

  • Erich Oberdorfer : Plant-sociological excursion flora . With the collaboration of Theo Müller. 6th, revised and expanded edition. Eugen Ulmer, Stuttgart (Hohenheim) 1990, ISBN 3-8001-3454-3 .
  • 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 .
  • S. Rauschert: Meadow and pasture plants. Detection, location and socialization, evaluation and control. , Neumann-Verlag Radebeul, 1961, 406 pp.
  • Radkowitsch, A. Zehm, A., Gehring, K. (2018): Water ragwort - Senecio aquaticus Hill . Ed .: Bavarian State Office for the Environment.

Individual evidence

  1. ↑ 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.  956 .
  2. ↑ a b c Jacobaea aquatica in Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved March 12, 2018.
  3. ↑ Erhard Dörr, Wolfgang Lippert : Flora of the Allgäu and its surroundings. Volume 2, IHW, Eching 2004, ISBN 3-930167-61-1 , p. 625.
  4. ↑ a b Radkowitsch, A., Zehm, A., Gehring, K .: Water ragwort - Senecio aquaticus Hill. Bavarian State Office for the Environment, 2018, accessed on July 17, 2019 .
  5. ↑ a b Werner Greuter (2006+): Compositae (pro parte majore). In: W. Greuter & E. von Raab-Straube (ed.): Compositae. : Jacobaea In: Euro + Med Plantbase - the information resource for Euro-Mediterranean plant diversity.

Web links

Commons : Aquatic Ragwort ( Jacobaea aquatica )  - Album with pictures, videos and audio files