Mexican Petunia...terribly invasive weed identified

The terribly invasive weed I have been fighting for 4 years in my north side yard has now been identified as a version of Ruellia called Mexican Petunia.  It comes over from my neighbor's hardly ever touched yard.  It spits seeds, loves disturbed soil, survives long droughts, and has impossible to uproot by hand roots (which break off just at the active part).  After a long drought kills enough lawn grass, Ruellia quickly takes over at the first light rain, and spits seeds into the next area.

There are some nice forms of Ruellia, I have also learned.