We are looking for two types of trees that will thrive in clay soil. 1. A dwarf tree that provides year round interest - perhaps a dwarf crab apple or other flowering tree. 2. A tree that does not exceed 25-30 feet. We were thinking of a smaller birch but noticed that they can get to 70 feet tall. We are open to suggestions for trees that will thrive in clay soil. They do not have to be Minnesota native trees. We are in Minneapolis Zone 5a. Sincerely, Lynn