Plants that are siblings: How does this impact pollination? A friend has two cherry bushes (prunus tomentosa). Prunus tomentosa is said to be partially self-fertile, but benefits from cross-pollination. The two cherry bushes set fruit, and so my friend saves me two seeds. I plant the seeds at my house, which is miles away from his, and now have two bushes of my own. They are in bloom. **My cherry bushes are siblings. How will this impact their ability to pollinate?**

In your case, your two bushes might well be half sib (the pollen might come from different donor) and one (or maybe even both) bush might result from selfing event. In any case, if the species is able to self, I don't see why full sib mating would cause any trouble.

Many species protect themselves from selfing. These plants are said to be self-incompatible. The evolution of the genetic mechanism underlying such self-incompatibility has been highly studied and is fascinating. The wikipedia article offers a good overview.