i believe when the pollen is made it sends off a single strand of DNA in the chromosones. this DNA or RNA or whatever the fuck it is called. containes the genetic makeup of them plant. it should be pretty consistent in all of the pollen spores.
now, with every genetic code there is recessive and dominant traits. this is where you get your phenotype, different traits are recessive and dominant in all of the offspring so the result will be a mix of mother/father genetics and all different phenotypes.
its been a long time since my bio 101 class but think of it as if it were a human...your sperm contains your genetic code. her egg contains her genetic code, only in this case its pollen and seed.
now you can get your wife pregnant with your first kid. and then 12 months later get her preg again with another child. assuming they are both female's these children can look verry similar or verry different. this is the phenotype. the same genetics go in both children, we know this because you can have your DNA matched with the child to prove that it is in fact your child. your DNA is like your "code" it always stays the same, same thing with plants.
my information may be a little inacurate as far as terminology goes but the concept im trying to distribute is still the same.
hope this helps