Thank you both for your input. I suspect Bonehead (love that handle by the way!) may be right- it was supposed to be the named variety, but what do you bet that the nursery just sowed seed from that variety and passed it off as the parent. It was so small when it arrived that it took 4+ years to flower. I'm sure they figured the average gardener would not know what it was supposed to have been by that point.
I guess I'll go with white/green NoID.