Damson
The damson, damson plum, or damascene, is an edible drupaceous fruit, a subspecies of the plum tree. Varieties of insititia are found across Europe, but the name damson is derived from and most commonly applied to forms that are native to Great Britain. Damsons are small, ovoid, plum-like fruit with a distinctive, somewhat astringent taste, and are widely used for culinary purposes, particularly in fruit preserves and jams.
Read on Wikipedia