Sweet cherries had spread to Ancient Greece and the Mediterranean by 300 BCE, for Theophrastus mentions them. Sour cherries have spread even farther north, and are a speciality of Germany and Scandanavia.
Sours are mostly self-fertile.
Wearing white for Eastertide. Now, of my threescore years and ten, Twenty will not come again, And take from seventy springs a score, It only leaves me fifty more. Fifty springs are little room, About the woodlands I will go To see the cherry hung with snow.