Ragwort photographed at the sand dunes at South Shields, near Newcastle upon Tyne in North East England, on 21 July 2012.

Ragworts contain poisonous Pyrrolidizine Alkaloids that are released both in the pollen and in the sap. Because it is a controlled weed, and landowners are obliged to dig it up and remove it from their land depending upon the risk it poses to animals and humans (although, strangely, Councils often fail to do their duty in this regard, and instead set a bad example). Those most at risk of poisoning are those weeding the plant, or during a hot spell in Summer when a lot of pollen may be released from a large infestation. Direct skin contact with the sap should be avoided, thick rubber gloves should be worn by those digging up the plant. The toxins are mostly concentrated in the pollen, with progressively decreasing concentrations within, respectively, the leaves, stems and then the roots. The toxins have a cumulative effect in the body, building up in the body as exposure increases until they reach critical levels when symptoms of serious and irreversible liver damage leading to liver failure occur. It is fast spreading along motorways, for each plant produces thousands of parachuted seeds that waft far and wide on the slightest breeze.

Horses and other grazing animals are at most risk of acute poisoning by Ragwort not only by directly eating the plant, but also if it gets mixed in with hay or bedding. However, they prefer not to eat it, and will only eat it if other grazing plants are in short supply. The toxic Pyrrolizidine Alkaloids are transferred into the milk of for example cows who eat the plants, and then into those who drink the milk. Similar transfer can occur into honey when bees visit plants containing these alkaloids, which can include a whole raft of species but mostly plants fromn the Borage Family and the Daisy Family (subgroup Senecioneae), and a few from the Pea and Orchid Families. Ragwort should not be burnt, as the emitted toxins can be inhaled by humans.

Several insects specialise on plants containing Pyrrolidizine Alkaloids, which they accumulate and use as defence mechanisms. The Cinnabar Moth on Ragwort is one such example.


Information from wildflower.org.uk.

 


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Last updated Thursday April 24, 2014