Ah, Yes, Wisteria.
Little known to most, there is a wisteria native to America. It is Wisteria frutescens. It is hardly ever planted here though, and usually the Chinese wisteria (Wisteria sinensis) is. Chinese wisteria is a weed! It is terribly invasive. My wife begged for one for over 20 years before I relented and planted two of them, one in the front yard and one on a pergola. I have been trying without success for over five years now to eradicate the pergola one; the front yard one requires heavy pruning twice annually to keep it from consuming the whole area.
Wisteria blooms ARE beautiful, but last only a week or two, then the vine becomes “triffid” like (See
http://en.wikipedia.org/wiki/The_Day_of_the_Triffids ) in it's inexorable advancement of creating a "little shop of horrors" landscape.
You may think you are getting rid of your wisteria, but I bet 10 gallons of roundup, it will be back!