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Senecio jacobaea or Jacobaea vulgaris*, ragwort

Important Note

With effect from 6th September 2011, this page is no longer being revised.

To ensure you are reading the most up to date information, please go to the Jacobaea vulgaris page.

Summary

Ragwort is one of today's most notorious plants but, in reality, the dead plant, unseen in a bale of hay, is far more harmful than all the living plants seen along roadsides and in fields.

*These days the name Jacobaea vulgaris is preferred because DNA tests have shown that the plants in the Senecio genus need to be split into Jacobaea and Senecio.

Family

Asteraceae

Meaning of the Name

Senecio
From the Latin senex meaning ‘old man’ because of the woolly, hairy seed of the plants. Senex is the root of the English ‘senior’.

In Scotland it is called stinking Willie because it spread in the path of William, Duke of Cumberland’s Culloden campaign.

The Scottish connection between Senecio jacobaea and the Duke of Cumberland leads some people to ask if the name comes from that.

John Gerard uses the name Senecio jacobaea so it predates the 1746 Battle of Culloden where it acquired the name ‘Stinking Willie’ after the Duke of Cumberland. The name, therefore, has nothing to do with the Jacobites.

Jacobaea
Possibly derived from St James or Jacobus. The phrase ‘conditio Jacobaea’ is used to mean ‘If the Lord wills it’ and is said to come from St. James’ instruction to examine all plans to see if they meet God’s will.  It may be that the pernicious ragwort could only be tolerated on the basis that it was part of God’s will. Images of St James tend to show him as an older man with grey or greying hair, somewhat unkempt.  It may be that the ragwort was thought to look like St James’ beard.

vulgaris
Commonplace, usually given to the most common species in a genus.

Common Names and Synonyms

ragwort, stinking Willie

How Poisonous, How Harmful?

Contains pyrrolizidine alkaloids (PAs) which are hepatotoxic and can cause complete liver failure.

There is no evidence that ragwort causes harm by contact or inhalation. In fact, there is very little evidence of harm to humans resulting from ragwort except for those with pre-existing liver damage and a couple of cases where very young children were given large amounts of an herbal tea made with ragwort which was said to be a cough medicine.

It has been found that, although the taste is unpleasant, cattle will eat ragwort if there is nothing else available. Interestingly, when returned to normal grazing land these animals are found to continue eating ragwort. This leads to speculation that ragwort is addictive and it should be noted that there are species of Senecio which have been used by Mexican Indians for their psychoactive properties.

Though there is no evidence of its harming healthy humans it is more of a problem for horses. This is because living ragwort is extremely unpleasant to the taste and animals will ignore it if there is something else available. If it gets into hay, however, it has lost the taste but, being one of the few plants which retains its toxicity after death, it will poison horses fed on the hay.

The symptoms it causes are described by the names given to its effects, ‘Walking Disease’ and ‘Sleepy Staggers’. It can cause blindness prior to death. Death comes from liver failure which results in the release of ammonia into the bloodstream which, in turn, destroys the brain.

It is often said that PAs are a cumulative poison. That is not the case but the liver damage caused is cumulative.

Misinformation about ragwort is very persistent but there are a couple of websites where the creators have gone to a lot of trouble to look at evidence and debunk the lies and myths.

The first is 'Ragwort Myths and Facts' and the second is 'Ragwort Facts'. The second is a purely text site with lots of information. What makes the first site so interesting is that it was created by a Dutch horse owner who took the time to look into the information about ragwort and found so much of it to be wrong. My link is to her English language site but the Dutch original has a great many useful photographs to aid identification.

Watch a Video about Senecio jacobaea, ragwort

Senecio jacobaea, ragwort

Senecio jacobaea, ragwort

Incidents

There are no cases that have ever been reported where poisoning to human beings has been found to have been caused by ragwort.

The only recorded cases of poisoning due to plants of the genus Senecio are all where a plant had been used to produce an herbal tea and long-term consumption had allowed the build up of liver damage.

Based on known levels required to poison horses, it has been estimated that a human would need to consume 14lb, 6Kg, of ragwort to ingest a lethal dose in one sitting.

There has been no research done on the effects of handling ragwort, which in itself suggests that this is not a problem, but research on Symphytum spp., comfrey, has shown that absorption of pyrrolidizine alkaloids through the skin of rats resulted in blood levels twenty to fifty times lower than those resulting from ingestion of the same amount. This suggests that a person would need to have, at least, 120Kg of ragwort applied to their skin to achieve the same effect as ingesting the 6Kg referred to above.

Folklore and Facts

It is an injurious weed under the Weeds Act of 1959 and landowners could be ordered to deal with it. Contrary to what is often said, it is not illegal to have it growing and landowners are not obliged to remove it. It is also not 'notifiable'. Under the Weeds Act, if the ministry becomes aware of a potentially harmful area it can order removal.

Ragwort is one of five plants included in the Weeds Act of 1959. The full list is;
common ragwort
spear thistle
creeping or field thistle
curled dock
broad-leaved dock.

The provisions of the Weeds Act still apply to ragwort. The Ragwort Control Act passed on 20 November 2003, which was sponsored by The British Horse Society, originated as a Private Member’s Bill, and was presented to Parliament by John Greenway MP. The Government gave its backing to the Bill and ensured its successful passage through Parliament. The Act came into force on 20 February 2004.

Ragwort is important to biodiversity

Ragwort is important to biodiversity

The Act called for the creation of a Code of Practice (COP) in respect of ragwort and the code was issued in July 2004. The purpose of the COP is to give a measure for determining whether action under the Weeds Act is appropriate.

The COP deals with the identification of ragwort, its safe handling, control and disposal and sets out the duties of livestock owners, forage producers and land owners.

One very important point to make is that it is NOT a requirement to remove ragwort in every case though it is the responsibility of the occupier of the land to take the appropriate action.

There is a great deal of misinformation about ragwort. A visitor to the Alnwick Garden Poison Garden was heard to say that she thought it was illegal to allow ragwort to grow. Her son, a smallholder, had been instructed to remove all ragwort from his land including that in a Site of Special Scientific Interest (SSSI). The COP says that English Nature MUST be consulted before ragwort is removed from an SSSI or other protected area of land.

The COP talks about the importance of ragwort to biodiversity and goes on to set out three risk levels:

High Risk:
• ragwort is present within 50m of land used for grazing by horses and other animals or land used for feed production.
Medium Risk:
• ragwort is present within 50m to 100m of land used for grazing by horses and other animals or land used for feed production.
Low Risk:
• ragwort or the land on which it is present is more than 100m from land used for grazing by horses and other animals or land used for feed production.

(Crown copyright material is reproduced with the permission of the Controller of HMSO and the Queen’s Printer for Scotland)

Immediate action to remove ragwort is only required for high risk areas. For medium and low risk areas, it is a matter of ‘wait and see’ but with plans being put in place in case the area becomes high risk.

The COP gives lots of information on removal, disposal and handling techniques. It calls for the wearing of strong gloves, keeping arms and legs covered and the use of facemasks to prevent inhalation. This reinforces the internet myths about ragwort being absorbed through the skin or inhaled. It is true that some people develop contact dermatitis from handling ragwort and mechanical damage can be caused by abrasion if a large number of planmts are pulled up but the PAs are not absorbed through the skin. As far as inhalation goes, the 2003 draft of the COP says that wearing a facemask is ‘to reduce the risk of hay fever’ but this wording is not present in the final version.

Ragwort was introduced in New Zealand in the 1800s. It thrived and became a noxious weed, which farmers sought to eliminate. In the 1930s, sodium chlorate was used as a weed-killer to try and bring ragwort under control. Sodium chlorate is very volatile and fumes penetrated cotton clothing making the clothing flammable.

Amongst the incidents reported was the farmer out riding when the friction between his saddle and his clothing caused the sodium chlorate to ignite. In another case, a farmer went straight from work to see his newborn son. When he struck a match to see the child better, his clothes caught fire and he burned to death.  

In spite of what has been described as an epidemic of exploding trousers, farmers were so pleased to find something that would control the spread of ragwort that they continued to use it until 1946 when a new type of weed-killer became available.

In 2006, the US TV programme 'Mythbusters' demonstrated the truth of the New Zealand experience which many people had assumed to be apocryphal.