It is tick seed. Don't let the plant go to seed. They are a pain to remove. The brush killer (triclopyr) will be fine if you don't over apply it. Page 4 http://www.bayeradvanced.com/tree-shrub-care/products/brush-killer-plus/sizes says it may cause temporary yellowing. I've never had that happen... yet. If you have anything that is labeled for dandelions that will work as well. The two plants are both in the same family.