This is Tarweed a very prolific weed and not one that you want in your paddock. I was about to ask for info on it because my research shows that it is toxic to livestock if eaten over time. My horses will not eat it in the paddock, but the danger is that if baled in hay, they will. Farmlands has suggested Spraying with Pulsar which I am in the process of doing. I would love to hear other opinions on this. A few this year means you will be over taken next year is my experience.