How excatly does berry breeding work in X and Y?

Question

Sometimes when you plant different berries next to each other the make a new berry that grows on the trees with the berry you planted. How exactly does that work?

Answer 1

I believe there are certain combinations of berries (eg. Mago + Iapapa = Pomeg) that have a chance to give you another berry, when they are planted next to each other.
Untill now I've got:
Mago + Iapapa = Pomeg
Persim + Chesto = Kelpsy
Some other combination I found:
Aspear + Leppa = Hondew
Oran + Pecha = Qualot

It seems as if this only gives you the EV berries.
The professor inside the house at the berry field will also tell you which combinations you've found so far.

Source: Experience, http://gaming.stackexchange.com/questions/135982/how-do-berry-mutations-work