Dang you Tom. You have 48 hours to post the next one...clock is ticking.
Those little individual pom-poms are clusters of flowers. It's S. albidum - I've seen it in leaf...although, the label on the tree could be wrong? I guess there could be another Sassafras species out there? This is in an arboretum, so the original plant collector could have gotten it from somewhere overseas - I'd be curious to know if this was mis-labeled. You should see it's color in the fall - dark, dark burgundy. I've never seen one this big, but then again, I'm not as old as a tree yet...