To begin with a tree peony in not truly a tree. It is more a shrub peony. Its stems are woody and botanically it is derived fom the species, Paeonia suffruticosa, which means "somewhat like a shrub."... Credit for much of the successful work with the early tree peony hybrids goes to A.P. Saunders who was a professor at Hamilton College. His devotion to the peony and its beauty led to the development of many superb hybrids. Since that time, many excellent plants have been made available. Their flower color range is wide and handsome. The best way to choose a particular variety is to observe them in bloom, study catalogs or ask professionals who know them.