Ragwort - Jacobaea vulgaris, Senecio jacobaea

Category: Medicines - plant based



Introduction and description

Jacobaea vulgaris, syn. Senecio jacobaea, is a very common wild flower in the family Asteraceae.  Two subspecies are accepted:

  • Jacobaea vulgaris ssp. vulgaris - the typical plant, with ray florets present.
  • Jacobaea vulgaris ssp. dunensis - the ray florets are missing.


Ragwort is native to the Eurasian continent, usually in dry, open places, and has also been widely distributed as a weed elsewhere.  Ragwort is abundant in waste land, waysides and grazing pastures. It can be found along road sides, and grows in all cool and high rainfall areas.

  •  Eurasia - In Europe it is widely spread, from Scandinavia to the Mediterranean.  Its common names include ragwort, common ragwort, stinking willie, tansy ragwort, benweed, St. James-wort,  staggerwort, dog standard, cankerwort, and stammerwort.
  •  In the United States - it has been introduced, and is present mainly in the northwest and northeast: California, Idaho, Illinois, Maine, Massachusetts, Michigan, Montana, New Jersey, New York, Oregon, Pennsylvania, and Washington. It is generally known as tansy ragwort, or tansy, though its resemblance to the true tansy is superficial.
  •  In South America - it grows in Argentina
  •  In Africa in the north
  •  On the Asian continent - in India and Siberia.
  •  In New Zealand and Australia – it has been introduced and has been declared a ‘noxious weed’.



The plant is generally considered to be biennial, but it has the tendency to exhibit perennial properties under certain cultural conditions (such as when subjected to repeated grazing or mowing).

The stems are erect, straight, have no or few hairs, and reach a height of 0.3–2.0 metres (1 ft 0 in–6 ft 7 in). The leaves are pinnately lobed and the end lobe is blunt. The many names that include the word "stinking" (and Mare's Fart) arise because of the unpleasant smell of the leaves.

The hermaphrodite flower heads are 1.5–2.5 centimetres (0.59–0.98 in) diameter, and are borne in dense, flat-topped clusters; the florets are bright yellow. It has a long flowering period lasting from June to November (in the Northern Hemisphere).

Pollination is by a wide range of bees, flies and moths and butterflies. Over a season, one plant may produce 2,000 to 2,500 yellow flowers in 20- to 60-headed, flat-topped corymbs. The number of seeds produced may be as large as 75,000 to 120,000, although in its native range in Eurasia very few of these would grow into new plants and research has shown that most seeds do not travel a great distance from the parent plant.

Ecological importance

Although the plant is often unwanted by landowners because it is considered a weed by many, it provides a great deal of nectar for pollinators. It was rated in the top 10 for most nectar production (nectar per unit cover per year) in a UK plants survey conducted by the AgriLand project which is supported by the UK Insect Pollinators Initiative. It also was the top producer of nectar sugar in another study in Britain, with a production per floral unit of (2921 ± 448μg).

In the United Kingdom, where the plant is native, Ragwort provides a home and food source to at least 77 insect species.
Thirty of these species of invertebrate use Ragwort exclusively as their food source and there are another 22 species where ragwort forms a significant part of their diet.

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 moth Tyria 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 tansy ragwort flea beetle (Longitarsus jacobaeae) also feeds on the plant.  Another beetle, Longitarsus ganglbaueri, also feeds on Ragwort, but will feed on other plants as well.

English Nature identifies a further 117 species that use Ragwort as a nectar source whilst travelling between feeding and breeding sites, or between metapopulations. These consist mainly of solitary bees, hoverflies, moths, and butterflies such as the small copper butterfly (Lycaena phlaeas). Pollen is collected by solitary bees.

Besides the fact that Ragwort is very attractive to such a vast array of insects, some of these are very rare indeed. Of the 30 species that specifically feed on Ragwort alone, seven are officially deemed nationally scarce. A further three species are on the IUCN Red List. In short, Ragwort is an exclusive food source for ten rare or threatened insect species, including the cinnabar moth (Tyria jacobaeae), the picture winged fly (Campiglossa malaris), the scarce clouded knot horn moth (Homoeosoma nimbella), and the Sussex emerald moth (Thalera fimbrialis). The Sussex Emerald has been labelled a Priority Species in the United Kingdom Biodiversity Action Plan. A priority species is one which is "scarce, threatened and declining". The remainder of the ten threatened species include three species of leaf beetle, another picture-winged fly, and three micro moths. All of these species are Nationally Scarce B, with one leaf beetle categorised as Nationally Scarce A.

The most common of those species that are totally reliant on Ragwort for their survival is the cinnabar moth. The cinnabar is a United Kingdom Biodiversity Action Plan Species, its status described as "common and widespread, but rapidly declining". This gives yet more evidence of ragwort's important role in maintaining the country's biodiversity and a vitally important component of the native flora.

Medicinal uses

Mrs Grieve

Ragwort was formerly much employed medicinally for various purposes. The leaves are used in the country for emollient poultices and yield a good green dye, not, however, permanent. The flowers boiled in water give a fair yellow dye to wool previously impregnated with alum.
The whole plant is bitter and aromatic, of an acrid sharpness, but the juice is cooling and astringent, and of use as a wash in burns, inflammations of the eye, and also in sores and cancerous ulcers - hence one of its old names, Cankerwort.
It is used with success in relieving rheumatism, sciatica and gout, a poultice of the green leaves being applied to painful joints and reducing the inflammation and swelling. It makes a good gargle for ulcerated throat and mouth, and is said to take away the pain caused by the sting of bees.
A decoction of the root has been reputed good for inward bruises and wounds. In some parts of the country Ragwort is accredited with the power of preventing infection.

Poisonous effects

Isabella Tree - Wilding

Ragwort is, indeed, a poisonous plant. It contains pyrrolizidine alkaloids - toxins that, when eaten in large quantities by mammals, cause liver-failure and death. But grazing animals have lived with it for tens of thousands of years. Our own longhorns, Exmoors, Tamworths, roe, fallow (and subsequently red) deer graze amongst ragwort with no adverse effects whatsoever.

They know to avoid it. The plant itself warns them away with its bitter taste and a smell so bad it has been immortalized in British history. …… In Shropshire and Cheshire its name is 'Mare's Fart'.

The problem of poisoning arises not in the wild but where fields and paddocks are overgrazed and the animals have no choice but to eat it, or when ragwort is cut into silage or hay and the animals are unable to detect and avoid it. Even then, the animal has to eat an excessive amount - an estimated 5-25 per cent of body weight for horses and cattle and 125-400 per cent for goats - for it to be fatal.

The source of the most recent wave of ragwort hysteria can be laid at the door of the British Equine Veterinary Association and the British Horse Society. In 2002 they published the results of a survey claiming that as many as 6,500 of the UK population of around 600,000 horses die every year from ingesting ragwort. It was an astonishing leap from the average of ten ragwort-associated horse deaths per year estimated by the Ministry of Agriculture, Fisheries and Food in 1990.

The BEVA's claim - it emerged - was based on bad science.

4 per cent of BEVA members had responded to the survey, reporting that they had seen, on average, three 'suspected' (note, not 'confirmed') cases of ragwort poisoning (note - not deaths) that year. The BEVA had then simply multiplied this average by the full BEVA membership of 1,945 to produce a total of 6,553 cases for that year. No one at the BEVA seems to have considered the most likely reason that the majority of vets failed to respond to their survey was that they had no cases to report.

Despite the fallibility of their reasoning and their having subsequently removed the misinformation from their website the BEVA-based myth has developed a life of its own, particularly in the folklore of horsiculture. As the old adage goes, a lie can get halfway round the world before truth has got its boots on.

Ragwort contains many different alkaloids. There is a strong variation between plants from the same location in distribution between the possible alkaloids and even the absolute amount of alkaloids varies drastically.  Dr Duke’s phytochemical database lists




·         C SENECIO-ACID








In areas of the world where ragwort is a native plant, such as Britain and continental Europe, documented cases of proven poisoning are almost non existent. Horses do not normally eat fresh ragwort due to its bitter taste.

There appears to be more evidence that animals are being poisoned by pesticides, fertilisers and contaminated foodstuffs   - other alkylating agents, such as nitrosamines and aflatoxins. Aflatoxins are a common contaminant formed in feedstuffs by moulds.

Even if the animal does ingest the plant, it has now emerged that at low doses the alkaloids are destroyed by the action of bacteria in the digestive tract before they reach the bloodstream.

Ragwort and people


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.

Isabella Tree - Wilding

A common misconception is that ragwort is poisonous to human touch even though the plant's pyrrolizidine alkaloids (which occur naturally in 3 per cent of all flowering plants) cannot be absorbed through the skin. Breathing in ragwort pollen, it is claimed, can give you liver damage, though this, too, is a physical impossibility.
Honey from bees feeding on ragwort was recently headlined in the Daily Mail as poisonous to humans, though DEFRA has described this risk as both 'highly unlikely' and 'negligible'. Bees invariably take nectar and pollen from numerous other poisonous flowers including foxgloves and daffodils. Yet none of these have ever been accused of poisoning honey.

Control legislation

Isabella Tree - Wilding

Opponents of ragwort, pointing the finger at the 'offensive weed' on other people's land, routinely claim the moral high ground. Landowners and local councils, they insist, are obliged by law to eradicate it wherever it occurs.  But this is categorically not the case.

Neither are the five weed species listed under the Weed Act 'notifiable'- there is no such concept in UK law………………….

The Ragwort Control Act of 2003 - an amendment to the Weeds Act of 1959 - Code of Practice, ….clearly states that 'common ragwort and other ragwort species are native to the British Isles and are therefore an inherent part of our flora and fauna, along with invertebrate and other wildlife they support. The Code does not propose the eradication of common ragwort but promotes a strategic approach to control the spread of common ragwort where it poses a threat to …… production of feed or forage.'

In summary

We are ignoring the potential medicinal value of this plant, as well as its ecological importance - and the tragedy cannot be over emphasised.  It may be anti-viral, or a chelator of harmful toxins given its reputed effects on rheumatism and gout.  The Greek physician Pedanius Dioscorides (c.40-90 CE) recommended the herb. The two "fathers" of herbalism, Gerard and Culpeper, also recommended the herb.   

In Hartwell, J.L. 1967-71. Plants used against cancer. A survey, Ragwort is mentioned.   Depuratives are herbs that are considered to have purifying and detoxifying effects.  In Steinmetz, E.F. 1957. codex Vegetabilis. Published by the author, Amsterdam; Ragwort is stated to be a depurative as well as of use against the colic. 

Steinmetz also lists it as an Emmenagogue -  a herb which stimulates blood flow in the pelvic area and uterus. Women use emmenagogues to stimulate menstrual flow when menstruation is absent for reasons other than pregnancy, such as hormonal disorders or conditions like oligomenorrhea (light menses).  

Ragwort was also once used as a cure for the ‘staggers’ [see right] and perennial ryegrass staggers is purported to be a common neurological mycotoxicosis of horses even now.  Lolitrem B is one of many toxins produced by a fungus called Epichloë festucae (var. lolii), which grows in perennial ryegrass.   All horses developed a variable degree of tremor and ataxia when exposed to lolitrem B. Limb swelling, heel lesions and serous nasal discharge are also observed in horses most severely intoxicated.  [PMID:  21793878].  So, on the one hand we get rid of meadows and replace them with perennial ryegrass, the ryegrass makes animals ill [many mammals not just horses] and meanwhile we grub up the one cure already recognised.

We are indeed fools -  illogical irrational ignorant fools.

Isabella Tree - Wilding

Despite these benefits to our wildlife, anti-ragwort propaganda has, in recent years, inspired eradication programmes anywhere that ragwort appears, including on roadsides and in wildflower meadows, and - incredibly - in areas designated for conservation as Sites of Special Scientific Interest. Broad-spectrum herbicides are often the chosen agent of destruction, causing inevitably collateral damage.

But even when uprooted by hand there can be losses to other flora. Other native yellow flowering plants - like hoary ragwort, marsh ragwort, tansy, St John's wort and hawkweed - are commonly mistaken for it. ‘Weeds’, as the saying goes, ‘are plants in the wrong place’ - only now, it seems, everywhere is the wrong place for ragwort.

To put ragwort in context, it is only one of a considerable number of plants that can be fatal if eaten by horses and other livestock. In Southern England common species that can kill grazing animals include foxglove, cuckoo pint, ivy, black bryony, white bryony, bracken, elder, spindle and yew. In March our woods in the Northern Block are carpeted with native wild daffodils a rare sight since nineteenth- and twentieth-century plant collectors dug most of them up else-where in the country. The daffodil - both wild and domesticated versions - is one of our most poisonous plants. A few years ago they almost killed a local vicar, who ate a bunch of daffodils.

References and further reading

  • Can J Microbiol. 2005 Jun;51(6):455-65. - Molecular analysis of a consortium of ruminal microbes that detoxify pyrrolizidine alkaloids.- Lodge-Ivey SL1, Rappe MS, Johnston WH, Bohlken RE, Craig AM.   PMID:  16121223
  • Am J Vet Res. 1978 Sep;39(9):1542-4. - Tolerance of cattle to tansy ragwort (Senecio jacobaea).  Johnson AE.  PMID:  567951
  • Ind Med Gaz. 1898 Feb;33(2):70-72. - Obstetrics, Gynæcology, and Pædiatrics:   Das K.   PMID: 29001769
    ·        Antipyrine as an Anti-Galactagogue
    ·        Hyperemesis Gravidarum
    ·        Quinine during Labour
    ·        Toxic Materials Absorbed from the Bowel as a Cause of Version of the Uterus
    ·        Apnœa of Premature Infants
    ·        On the Use of Senecio in Disorders of Menstruation
    ·        Phenacetin for Pain in Cancer of the Uterus
    ·        Airol in Ophthalmia Neonatorum
    ·        New Methods of Resuscitating Still-Born and Feeble-Born Infants.
  •   Pharmazie. 2013 Jul;68(7):636-9. - Toxic pyrrolizidinalkaloids as undesired contaminants in food and feed: degradation of the PAs from Senecio jacobaea in silage.  - Becerra-Jiminez J1, Kuschak M, Roeder E, Wiedenfeld H.     We show that ensiling will not lead to PA-free silage.   PMID: 23923650

Related observations