A few trees still have flowers

For the most part, the trees are green with leaves, and the flowers on trees have been gone for weeks.  However, there are a few trees that still have some flowers, including:

Hawthorn:

Catalpa:

And there was a tree that I did not know, so I photographed flowers, leaves, and trunk so that I could look it up:

It has opposite leaves, so there aren't that many things that it could be.  I went through the list at http://sibleyguides.blogspot.com/2009/10/trees-with-opposite-leaves.html and googled photos of each kind, until I came to one it seemed to match, which was Japanese tree-lilac.