By this time of year this biennial plant has been pulled root and all on most farms as it is poisonous to grazing stock. If left unmanaged it can become an invasive species in a man made environment - each plant having thousands of aerodynamic seeds.
As a native plant the yellow and black cinnabar moth caterpillar thrives on it. When removed from the land the moth moves onto groundsel which thrives naturally. This results in the red and black cinnabar moth being seen.
Not to be confused by the Oxford Ragwort that has not arrived here yet, originally from the slopes of Mount Etna that was introduced in 1796 to a private botanical garden. It soon spread along the train tracks of the UK and while harmless just as nectar rich for insect life.
N.B. By Ian the farmer @treflachfarm - While a toxic build up can occur in the liver of ruminants who eat a great deal of ragwort they don't usually go for this bitter tasting plant. Often ragwort poisining occurs when the animal has little other choice due to the high prevalence of the plant. We here at Treflach Farm have a nuanced approach to ragwort management. Where cattle will/are grazing or where we plan to cut for hay we manage the plant by pulling it out. Where there are free draining sunny slopes (usually south facing) where the cattle won't be going we leave this striking, spindly plant to flower as it is such a hub of invertebrate activity in the summer months.