The flower heads look like tiny marigolds, but the seeds are what you are most likely to notice. They catch in your clothes (or in an animal’s fur, but they almost seem designed for human-made fabrics) and take a ride to some other location that, with any luck, will be hospitable to Bidens bipinnata. These plants were growing against a fence in Beechview.

For a description of the species, see the Bidens bipinnata reference page.