I am writing this blog note from Rte 89 on the way on a road trip from Hoover Dam to Glacier and back to Benicia by the end of the month.  Can't get a picture but to describe the plant in question is the best I can do.  This is the third year in a row I found a volunteer amongst my roses.  While I was busy ruminating about what it might be , it grew.  And grew and grew.  I became convinced it was a rogue giant sunflower.  It never flowered.  I cut it down when I began to feel like the leaves would swallow my house.  But it grew back.  One major stalk abou 2" across. A minor pup only 1".  When we left on our road trip, the plant was at least 12' tall with leaves the size of a baby blanket.  No flower, ever.  I submit this as a teaser:  what is it?  Next time I will  submit it with a picture.  Call me stumped.