Blackthorn (Prunus spinosa)
The Sloe is the fruit of the Blackthorn. Blackthorn is the first of our hedgerow plants to flower each spring with that lovely 'dusty' look as the flowers come out before the leaves.
The fruit is navy blue or black and has a sort of 'misty' coating or bloom. It is one of the larger fruits at about 1.5cms in diameter.
I have never tried eating a Sloe but some people do use it to flavour gin and other spirits. My book describes the taste as very astringent, I guess that means sharp, or perhaps sour, and it is not a popular fruit with birds and mammals, probably because of this.
There is not a lot of flesh on a Sloe, just a thin covering of the stone inside, despite being a close relative of the plum. The fruits tend to just go on ripening to a point where they fall to the ground and, once there, the outside flesh continues to rot away leaving the stone or seed to germinate forming a new plant.