I think what I see around here is a great example of that. I have about two dozen or so apple trees that have self-propagated. They don't grow in any particular

I think what I see around here is a great example of that. I have about two dozen or so apple trees that have self-propagated. They don't grow in any particular pattern and they're randomly separated so I assume no one deliberately planted more than one or two of them. The fruit is small: averages about 1 - 2" diameter. A few of them produce really delicious, sweet apples but the majority are very sour and unpleasant. I've always been really surprised by how different the fruit on one tree is from the one right next to it.