It will be mine....oh yes it will be mine......

So as I'm hosting festival of the trees this month, I figured a few more garden/tree bloggers may be popping by the blog and I figured one or more of you may be able to help me. You see a few months ago in the Arnold arboretum I came across a small Magnolia sapling with these magnificent flowers on.

I must have it. I mean look at the size of them. Now typically in this situation I'd google a supplier, converse with mes parents, we'd agree on a spot in the mini-arboretum and said tree/shrub would join our little family collection (which is far to big for the space already).

Except this plant wasn't labelled and I don't have a clue which species it is (I'm thinking its probably an american one but am stuck). If it was just the flowers I could probably forget it but look at these awesome leaves. I must have it!

Anyone able to help me out?

P.S. I kinda think it might be M. macrophylla - anyone agree?
P.P.S. In addition (hopefully) to the answer to the above query a very cool post is coming soon. Watch this space.