purple plum leaf

Prunus cerasifera
cherry plum
The purple color of this purple leaf plum is due to an abundance of anthocyanins in the foliage.

Anthocyanins (also anthocyans; from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = blue) are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH.