I decided to try and key this plant out. The closest I got was Prunus. When I looked at where the petiole joins the leaf blade, I noticed two very large glands. Most, if not all Prunus have glands in this location on the leaf. Next I looked through image on Google for "Prunus with long clusters of white flowers". I have decided that this tree is Prunus lustitanica with out-of-season flowers that have not fully opened yet. I have never seen this tree, but I found an image of it growing in Vancouver. For anyone who has seen this species... do the images look like Prunus lustitanica.
Sec. Padus cherries like P. virginiana or P. padus - you must have taken the pictures during the growing season, when these were in leaf and in flower.
I am sure it is not Prunus virginiana or P. padus for I have seen both of these. The leaves of these species are much smaller and the teeth are finer. I think that that all the images were taken the same day, so that is why I assumed the flowers are out-of-season. Thanks Ron for your suggestions.
