Not only is this a "weed," but it is a "noxious weed" - aka a "thistle." But it is also a flower and when I was taking pictures of this intriguing plant, I was wondering what makes some flowers (roses and lillies, for example) "flowers" and what makes others (Canadian thistle and dandelions) "weeds?" I have my theories, but I'm playing coy today. I'll let you ponder this deep and profound mystery.