As Clint was alluding to, Bugweed, technically has a clone of a plant from like 4 decades ago. If I understand correctly, the original plant is long gone, but its clones keep going and going and... Aside from flowering / producing seeds, they also do "vegetative propogation", whereby new plants form as offshoots from the adult plant. They also sprout from leaves that are loosely embedded in soil media.
But the question you were asking is about the longevity of a particular plant. That I can't tell you, but I'm sure that there others who can. Most of us kill our respective plant within a couple years, especially within the first few months!