Senecio jacobaea Ragwort
Hierba de Santiago
Ragwort was originally native to the whole of Eurasia but has now spread to several continents. It flowers from June to October and can grow to a height of 80cms. It can be biennial or perennial. In the UK it is a food source for 77 species of insects, plus another 22 species that use it as part of their diet. Another 117 species use it as a nectar source whilst they are travelling.
Ragwort also contains many different alkaloids which make it poisonous to horses, goats and pigs. Horses tend to avoid it when it is fresh as it is too bitter for their taste. It is a danger when it is included in hay and can cause irreversible cirrhosis of the liver. Goats and pigs can suffer the same but at a much slower rate than horses.
Humans with sensitive skin can react to it with dermatitis. An excellent plant for insects, but not so good for larger animals unfortunately.