Ragwort

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Asterales
Family:	Asteraceae
Tribe:	Senecioneae
Genus:	*Senecio*
Species:	*jacobaea*

Binomial name

Senecio jacobaea

Ragwort (Senecio jacobaea) is a common wild flower in the Family Asteraceae that is found throughout Europe, usually in dry, open places. Alternative names include Tansy ragwort, St. James-wort, Ragweed, Stinking Nanny/Ninny/Willy, Staggerwort, Dog Standard, Cankerwort, Stammerwort and Mare's Fart. It has a long flowering period lasting from June to November. The many names that include the word "stinking" (and Mare's Fart) arise because of the unpleasant smell of the leaves. The leaves are pinnately lobed and the end lobe is blunt. The flower heads are 1.5-2.5 cm in size, and are borne in dense, flat-topped clusters.

Ragwort is the bane of people who keep horses. Although horses do not normally eat Ragwort due to its bitter taste, if the growth is particularly dense or if it has been picked and dried out, and some is taken while grazing, the result can be irreversible cirrhosis of the liver. Sheep, in marked contrast, eat small quantities of the plant with relish and without apparent harm. People trying to eradicate the plant by pulling it are cautioned to wear gloves, since there is evidence that it can cause liver damage in humans who do not take such precautions.

Ragwort is the national flower of the Isle of Man, where it is known as Cushag. The poet John Clare also had a more positive opinion of the plant, as revealed in this poem of 1831:

Ragwort thou humble flower with tattered leaves

I love to see thee come & litter gold...

Thy waste of shining blossoms richly shields

The sun tanned sward in splendid hues that burn

So bright & glaring that the very light

Of the rich sunshine doth to paleness turn

& seems but very shadows in thy sight.

Ragwort is the food of caterpillars of the Cinnabar Moth, Tyria jacobaeae. The larvae adsorb toxins from the plant and becomes poisonous themselves, a fact advertised by the black and yellow warning colours. The red, day-flying adult moth is also toxic or 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 the western US it is generally known as Tansy ragwort, or even more confusingly Tansy, though its resemblance to the true tansy is superficial at best. This is a potentially dangerous misuse of names, since the true tansy has been used for culinary purposes.