The Huge Weed at Our Vacation Home

We have lived in I  beautiful Ontario, Canada most of our lives so we are used to gardening in Zone 6A.  We know what is considered weeds and what isn't.  Our vacation home is in US Hardiness Zone 9B.  We bought it in March of 2010 but did not see it until May of 2010.  The house had been empty for over a year so there was a bit of overgrowth.  While we have become accustomed to some of the