Sauerkirsche
"Prunus fruticosa", a tetraploid with 2n=32 chromosomes, is thought to be one of the parent species of "Prunus cerasus" (the sour cherry) by way of ancient crosses between it and "Prunus avium" (the wild/sweet cherry) in the areas where the two species overlap. Both species can interbreed with each other, as well as with "Prunus cerasus".