Bullace -

: They can be dark purple ("Black Bullace") or yellowish-green ("White Bullace") and often have a distinctive waxy, powdery bloom on the skin.

For a concise and helpful overview of the ( Prunus domestica subsp. insititia ), the Tree Spotters Guide by Friends of Selsdon Wood provides a clear, illustrated summary for identification and comparison with its relatives like the sloe and damson. Key Identification Features bullace

: Unlike the thorny blackthorn (which produces sloes), bullace trees have fewer or no thorns and grow as small trees or large shrubs. : They can be dark purple ("Black Bullace")