Asked July 10, 2016, 11:04 PM EDT
Boulder County Colorado
Thank you for attaching the images. Your tree is a smokebush, or smoketree, Cotinus coggygria, so named because the airy flower clusters look like smoke. Leaves may be green or purple.
A full description is here - https://pubs.ext.vt.edu/2901/2901-1068/2901-1068.html