Caesar Weed is terribly, terribly invasive. It has taken over parts of our preserves. I've even volunteered with the Tampa Bay Estuary Program to pull this weed. It's as bad as Air Potato or Kudzu. The seeds are burs that will stick to everything. I once came out of the woods with them from my hair to my shoelaces. They were even stuck to my iPod cover! The flowers are small and pink but I have not seen them attract pollinators. My neighbor behind me has these all over his roughly 10 acres and I'm trying to keep them from getting into my yard. I highly advise pulling it. I wouldn't even add it to a compost pile for fear of spreading it.
