Superior is cross of Burbank and Kaga(A. hybrid). Burbank is pure Japanese(salicina) and those genes can pollinate Satsuma(salicina). Toka is an American hybrid but without salicina, Prunus americana x P. simonii. Toka is a great pollinator for American hybrids because of the long bloom period. In zone 5 Toka is the strongest and nicest looking tree but Superior has the best flavored plums. I grow superior on three sites and one Toka.

So, I take it Superior will and Toka won't pollinate Satsuma.

Do I also infer that Superior and Toka cross pollinate each other?

Yes and yes.

Satsuma was imported from Japan a hundred years ago. It is one of those rare Japanese type plums that do well in the east but it will pollinate more readily in the arid western conditions.

I had thought that all of the diploid plums would generally pollinate each other -- all but the European plums are diploids. That is how siliciana x americana crosses were created to begin with, they are the children of a pollination event between a pure saliciana and a pure americana. Some combos probably work better than others.

Scott

Thank you both. Very complicated. I needed real expert advice and I got it from you two.