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Ragwort

Jacobaea vulgaris

Summary 7

Jacobaea vulgaris, syn. Senecio jacobaea is a very common wild flower in the family Asteraceae that is native to northern Eurasia, usually in dry, open places, and has also been widely distributed as a weed elsewhere.

Comments 8

Senecio jacobaea is a weed introduced from Europe and now well established in places of cool, damp summers. It is toxic to livestock and legally noxious in most states and provinces where it occurs.

The Russian botanist E. Wiebe (2000) resuscitated Jacobaea for plants that are treated here as Senecio jacobaea,S. erucifolius, and S. cannabifolius. Phylogenetic studies may confirm the utility of recognizing Jacobaea as a distinct genus; to do so here would be premature.

Poisonous effects 9

Ragwort contains many different alkaloids, making it poisonous to certain animals. (EHC 80,section 9.1.4). Alkaloids which have been found in the plant confirmed by the WHO report EHC 80 are -- jacobine, jaconine, jacozine, otosenine, retrorsine, seneciphylline, senecionine, and senkirkine (pp322 Appendix II). Other alkaloids claimed to be present but from an undeclared source are acetylerucifoline, (Z)-erucifoline, (E)-erucifoline, 21-hydroxyintegerrimine, integerrimine, jacoline, riddelline, senecivernine, spartioidine, and usaramine.

Ragwort is of concern to people who keep horses and cattle. In areas of the world where ragwort is a native plant, such as Britain and continental Europe, documented cases of proven poisoning are rare. Horses do not normally eat fresh ragwort due to its bitter taste. It loses this taste when dried and can become a danger in hay. The result, if sufficient quantity is consumed, can be irreversible cirrhosis of the liver of a form identified as megalocytosis where cells are abnormally enlarged. Signs that a horse has been poisoned include yellow mucus membranes, depression, and lack of coordination. Animals may also resort to the consumption of ragwort when there is shortage of food. Sheep and goats suffer the same process of liver destruction but this is at a reduced rate compared to that in horses and pigs.

There is no definitive test for the poisoning however, since megalocytosis is not a change in the liver which is specific to ragwort poisoning. It is also seen in poisoning by other alkylating agents such as nitrosamines and aflatoxins. Aflatoxins are a common contaminant formed in feedstuffs by moulds. Research in the UK has produced results showing megalocytosis, which may be due to various causes, to be a relatively uncommon cause of liver disease in horses.

The danger of ragwort is that the toxin can have a cumulative effect. The alkaloid does not actually accumulate in the liver but a breakdown product can damage DNA and progressively kills cells. About 3-7% of the body weight is sometimes claimed as deadly for horses, but an example in the scientific literature exists of a horse surviving being fed over 20% of its body weight. The effect of low doses is lessened by the destruction of the original alkaloids by the action of bacteria in the digestive tract before they reach the bloodstream. There is no known antidote or cure to poisoning, but examples are known from the scientific literature of horses making a full recovery once consumption has been stopped.

Ragwort poses little risk to the livers of humans since, although it is theoretically poisonous to humans, it is distasteful and is not used as a food. The alkaloids can be absorbed in small quantities through the skin but studies have shown that the absorption is very much less than by ingestion. Also they are in the N-oxide form which only becomes toxic after conversion inside the digestive tract and they will be excreted harmlessly.

Some sensitive individuals can suffer from an allergic reaction because ragwort like many members of the compositae family contains sesquiterpine lactones which can cause compositae dermatitis. These are different from the pyrrolizidine alkaloids which are responsible for the toxic effects.

Honey collected from ragwort has been found to contain small quantities of jacoline, jacobine, jacozine, senecionine, and seneciphylline, but the quantities have been judged as too minute to be of concern.

Biological control 9

Ragwort is a food plant for the larvae of Cochylis atricapitana, Phycitodes maritima, and Phycitodes saxicolais. Ragwort is best known as the food of caterpillars of the Cinnabar mothTyria jacobaeae. They absorb alkaloids from the plant and become distasteful to predators, a fact advertised by the black and yellow warning colours. The red and black, day-flying adult moth is also distasteful to many potential predators. The moth is used as a control for ragwort in countries in which it has been introduced and become a problem, like New Zealand and the western United States. In both countries, the ragwort flea beetle (Longitarsus jacobaeae) has been introduced to combat the plant. Another beetle, Longitarsus ganglbaueri, also feeds on ragwort, but will feed on other plants as well, making it an unsuitable biological control.

Sources and Credits

  1. (c) anonymous, some rights reserved (CC BY-NC), http://www.biopix.com/photos/JCS-Senecio-jacobaea-60549.JPG
  2. (c) Peter O, some rights reserved (CC BY-SA), http://www.flickr.com/photos/58414938@N00/3907932956
  3. (c) anonymous, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/8/8c/Jacobskruiskruid_bloeiwijze_Senecio_jacobaea.jpg
  4. (c) anonymous, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/c/c6/Jacobskruiskruid_Senecio_jacobaea_subsp._dunensis.jpg
  5. (c) anonymous, some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/b/bb/Jacobskruiskruid_in_voorjaar_na_bloei_vorig_jaar_%28Jacobaea_vulgaris%29.jpg
  6. (c) anonymous, some rights reserved (CC BY-NC), http://www.biopix.com/PhotosMedium/JCS%20Senecio%20jacobaea%2039059.jpg
  7. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Jacobaea_vulgaris
  8. (c) Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/19786763
  9. (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Jacobaea_vulgaris

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