Per the WSU fruit booklet EBO0937, all pie cherries are self-fertile and usually are not good pollinators for sweet cherries because the typically bloom later. Since my trees do coincide in bloom, I am fairly sure Montmorency is pollinating Sam. As luck would have it, the WSU booklet addresses several specific varieties but not Sam.
**Edited to apologize for not including web links but I am struggling without a computer and using my Nook for web access - no clue how to cut/paste on this tiny device.
