In article , Bobo
Bonobo? writes
In order to get my cherry trees to have cherries, I had to plant two
dissimilar varieties. This is what I don't get. Variety A needs a
var B to pollinate it. Var A produces cherries. I plant the seed.
Presumably this seed has DNA from both A & B. When this seedling
matures it will require a pollinator in order to make cherries. How
would I know if it needed an A or a B type?

I can't speak for cherries, but I suspect that in general you wouldn't
know. Depending on the mechanism of self-incompatibility, the seedling
could be compatible with both A and B, one of A and B, or neither A and
B - and another seedling from the same cross may be different.

The web has over 500 pages which contain the terms "Prunus" and "self-
incompatibility"; a significant proportion are on self-incompatibility
in Prunus. URL:http://www.google.com/search?num=100&hl=en&lr=&ie=ISO-
8859-1&as_qdr=all&q=Prunus+self-incompatibility. Hopefully one of these
pages will explain how it works in Prunus.

In species where varieties are self infertile, how is it that the
varieties can stay in any way distinct?

They are propagated vegetatively.

I'm 43 and I've wondered about this for most of my life, so thanks in
advance for your replies.

--
Stewart Robert Hinsley