This was in a pot of another plant I purchased. Not being sure what it was, I planted it at the very edge of my yard. I have never been able to find it in any of my books, but I haven't really searched very hard. I was wondering if anyone here recognizes it? It has been in the ground for probably 8 years and hasn't become invasive. The plant I bought with it has long since bit the dust, but this seems to keep going.