My books from the 50's say 5 flower types, another publication in 1980 says there are eight. A recent article argues with both. Most people are familiar with the Bomb and the Rose, or fully double forms. I have found three other types of blooms much more pleasing to my eye. The Single consists of a few broad petals with a center of pollen bearing stamens and seed bearing carpels.
Japanese types have the beginning of doubling.
In the Anemone, the anthers have disappeared. All are simpler in form and clean of line, giving a grace not found in the heavier Bombs. Peony foliage can vary considerably in height and appearance. The smaller varieties begin at about fourteen inches. Most will be two to three feet in height.