Few apricot varieties are reliably hardy in Iowa. Moongold and Sungold are hardy and self-unfruitful. Plant at least one of each for proper pollination. Most varieties are self-unfruitful. Most peach varieties are self-fruitful.
Most pears are self-unfruitful.
A few varieties, such as Kieffer, will set a fairly good crop without cross-pollination. However, for maximum fruit production plant at least two different varieties. However, some European and hybrid plums can be successfully grown in the state. European plums are partially to entirely self-fertile. European plums will not pollinate the hybrid plums and vice versa.