Sloe

Prunus spinosa is a deciduous large shrub or small tree growing to 5 m tall, with blackish bark and dense, stiff, spiny branches. The fruit, called a "sloe" is black with a purple-blue waxy bloom, ripening in autumn, and harvested — traditionally, at least in the UK, in October or November after the first frosts. Sloes are thin-fleshed, with a very strongly astringent flavour when fresh