Common Ragwort (Senecio jacobaea)
Common Ragwort presents us with two problems. Firstly it is poisonous to cattle and horses and so there is always a risk if these animals are around the plant. In reality, it seems to me cattle eat everything around the Ragwort and leave the Ragwort well alone.
The other problem is its capacity to set seeds and spread. It is a prolific plant and in some years it can be more abundant that others but it is always abundant! You can find it on waste ground, hedgerows, pastures, dunes, downland; just about anywhere, especially if the ground is regularly disturbed or the general vegetation is sparse.
Hated by humans it may be but it is adored by insects and is another plant worth closely watching if you like insects.