That could be it. I'm finding it pretty difficult to differentiate between the varieties. As far as I can tell, this is native, as it's just growing amidst the weeds and shrubs. I was looking at V. lentago, V. prunifolium, and V. cassinoides too. They all look pretty similar to my novice eye. Maybe the berries will help me narrow it down further.

Not a leatherleaf viburnum (Viburnum rhytidophyllum). Might be its hybrid V. x rhytidophylloides.

You might check in used Book Stores for a cheaper copy. We have two college book stores in Lansing, and often GREAT bargins to be found. There are a lot of courses on Landscaping, shrubs and trees, so Dirr's book comes and goes. I got mine, recent edition then, used slightly, for $25. Ebay is another good source, got my Latin translation on plant names book there for $5. INVALUABLE when I did the Shrubs cleass. Thanks for the sad news on zone, but that happens. I am a zone 5 for sure. Don't need any more bushes to coddle. One tender Japanese Maple is enough. He sure is cute though. I have some shrub cuttings coming along. Interesting to read that note on them above, Just learned how to do that! Not sure what I will do with all these orphan shrubs, but they will find a home.

So bottom line 1 viburnum doesn't influence another's ability to flower, ONLY the berries, correct? Correct - flowering is affected by sun exposure and plant maturity. Viburnum x rhytidophylloides 'Allegheny' is the cultivar itself (as denoted by the single quotes around the name). The official name for Mohican is Viburnum lantana 'Mohican'. The key for cross pollination is overlapping bloom times - without that, it won't happen. And for some viburnums, they are not compatible even with overlapping blooms. Here is a link that might be useful: You might enjoy this thread