I suspect the answer to this is "no", and that what I'm seeing is rootstock, but would like to hear the answer, anyway. I have this great big thicket of GMB, and I know for a fact that it has some rootstock growing in there, but the problem is determining which is rootstock and which is scion when it's not flowering. Like most roses around here, the rootstock is 'Laxa', and I can't tell it from an Alba when it's not in bloom. Except for the hips, perhaps. Let me know, folks. Thanks.