There are a few that look like this ...,  And not sure why it is grafted, as they are all easy on their own roots. I have one that is named M. craigii (syn - sonorensis 'craigii') that is similar and same flowers, montensis is another, petterssonii another similar and zuccariniana. But I think there are more and they can vary. Personally, I think that one is probably craigii, but really cannot be sure.