I made an effort to look up what that plant might be, the closest thing I could find that resembled it was some sort of thistle, there are like 10-20 different species of the things and most of them have those spiky purple flowers. The leaves are also spiky too. It's native to europe, or at least that's what the internet tells me.

I leave them alone if they're on land that's not my responsibility (otherwise it's weedwhack them if they're young, mow them if they're not, blast them with glyphosate if they're in the ditch), and they can grow to 6 feet or so before they put out those spiky blooms. I've seen them do this enough times coincident with the beginning of summer, that I use them as a marker for it.