Identification: Avium 'Plena' - large tree, double whites, mid-to-late season

This is not a question, but comments and corrections are very welcome.

The Avium ‘Plena’ is a double flowered version of the mazzard or sweet cherry, though it is an ornamental and does not produce cherries. The dense white blossoms appear at the same time as the green or bronze-green leaves. This can be quite a large tree. Photos were taken April 19 on Highbury St in Vancouver.

 

Here are two more photos from last year to show better what these trees look like, in full bloom and with the sepals curled up the way the single Aviums do. The tree and blossom photos are not from the same trees.

 

These are from the same tree. Are these clusters umbels?