The reason that it is so hard to get rid of, it is tuberous!!!
At my preserve we had a huge, 10 or 12 stem monster that was getting in the way of a bench and an informational display. Just for fun, we dug down into the soil and I have to tell you it was like we were harvesting YAMS 🍠!! Big yams.
They were connected by roots and smaller tubers and I have a funny feeling in that unless you destroy the entire tuber, that sucker will grow back in short order.
Too bad they are not yams. I love sweet potato fries!!