Alder buckthorn.
On one of our common bushes – the alder buckthorn (Frangula alnus) – berries of two colours can be seen, red and black. As they ripen the berries are reddish, but become black when quite ripe. But neither kind should be eaten, the fruits of the bush are poisonous. If you have doubts about the identity of the bush, then look at the bark: the bark of the alder buckthorn look as if little white dashes or dots had been drawn on it. When the bark is cautiously scraped, the yellow wood shows.