I can't believe this, but yesterday while weeding on the south side of my house, I came upon this little purple thing. I reach down and ouch, it's got thorns. Get a lower grip and a better grip and yank the sucker up. It was a volunteer jap barberry. I don't have jap barberries, but the house a block north of me does. I'm in small town USA, not on a large lot and here I've got a nice gift from a neighbor. So just because you live in suburbia, or a town like me surrounded by corn and beans, it does, and it will, spread.