I like the hedge evergreen boarder and circles of dwarf boxwoods filled with various plants! What are the approximate dimensions of the boxwood circles? Are all four the same size or is the one in the back corner slightly larger? What plants are on the inside of each boxwood circle? Also, what kind of tree is in the center of the one in the back corner? I ask since I have a 10x21 foot space and wonder if two or three circles similar to these depicted would fit and look right. Thanks in advance!