Cephalaria gigantea

Has any one ever tried to dig on of these 12 foot tall yellow scabious like herbaceous plants out? The roots are like thick ropes and go down a long way. Now I was wondering just how persistent are they? I mean are they like Horseradish where every tiny piece will re grow or what?

 

You can propagate by dividing them so I would assume that it might grow from a stray piece of root.