Perhaps a purple leaf plum.

Sec. Padus cherry as in P. padus or P. virginiana. Purple-leaved forms of both are much grown in North America and the two related species are similar to one another, told apart by details like the surfaces of their fruit pits. Their leaves starting green and then going purple in a conspicuous manner is an occurrence more or less peculiar to the purple-leaved horticultural selections of these trees, at least among frequently seen decorative trees and shrubs. As we can see in this picture their seedlings often come at least partly true, as is the case with purple-leaved Japanese maples and Norway maples.