I read that for almond trees, you should plant another tree of a different variety. That confuses me.
I had always thought that if you planted different varieties of the same kind of plants near each other that the fruit/vegetable would cross-pollinate and wouldn't bear 'true'. jFor instance, if you planted a bell pepper near a hot pepper, the hot pepper wouldn't be as hot, and the bell pepper wouldn't be as mild, because they would end up sharing qualities.
This is what i understand of the cross pollinateing. Many trees require two different types of same tree.Example a red delicious apple may bear better if pollinated with a granny smith.The changes in varietys takes place in the offspring from seeds not the fruit itself.This does not happen in nature easily due to heavy self pollinateing of the trees along with neighbor tree`s pollen.Hybridizers polinate with a single donor and prevent any other donors by covering flowers with plastic. The resulting seeds are planted createing new varietys of hybrid plants.