Ragwort. I have some plants in my garden, I'm keen to always have some as the flowers attract several different species of flies. Syrphidae, Tachinidae, and Conopidae mainly, I've had some rare species on them. They are biennial.
https://www.google.co.uk/searc...
The caterpillar of the Cinnabar Moth feed on it, don't take notice of scare stories about poisoning horses if you don't have horses. It's been the subject of controversy and unnecessary destruction.
