Jacobaea vulgaris (syn. Senecio jacobaea), common ragwort.

Thank you :o)

Yes, ragwort, a weed.

Please don't let it set seed - Common Ragwort (Senecio jacobaea) is a specified weed under the Weeds Act 1959. It contains toxins, which can have debilitating or fatal consequences if eaten by horses and other grazing animals2.

but it is also an excellent source of food for native butterflies / moths. thats the double edged sword sadly. Rabbits quite like it too.

I am told its only fatal if harvested and dried with hay - otherwise horses won't touch it - this from a great equestrian friend.

There is a whole big debate about Ragwort going on at present. This makes fascinating reading.
http://www.ragwortfacts.com/
Then you can decide for yourself.

There are many fields with horses in our area. At one time you could see the owners going round the field and carefully pulling every plant. Now, they don't bother and just let them grow.

we still pull ours up in the horse fields because it spreads like - well like a weed. You have to get up all of the root or it will come back

The flowers are surprisingly attractive in close up.

Any plant in my garden that has a yellow flower is deemed a weed. A most of the native 'wild flowers' round here have yellow flowers.:-)

Very interesting, thanks for all the information.