A peony is a perennial flower with large blossoms and popular with home gardeners.
Peonies have grown in China for more than 4,000 years.
Two common and popular varieties are the Paeonia suffruticosa or tree peony and Paeonia spp. hybrids or garden peonies, according to the University of Rhode Island.
There are nine types of peony flowers to classify tree peonies, with anywhere from one petal to six, according to Treepeonygarden.com. The single form flower may have anywhere from one to three petals, while the chrysanthemum form can have up to six petals per flower.
The form of the flower is how garden peonies are classified. According to the University of Rhode Island, "all peonies have five or more large outer petals called guard petals and a center of stamens or modified stamens. Single forms have centers of pollen-bearing stamens. Centers of semi-double forms consist of broad petals intermingled with pollen-bearing stamens. Double types have dense centers of only broad petals."
Fungal diseases such as botrytis blight and leaf blotch are serious problems for peony flowers. According to the University of Rhode Island, botrytis causes the stems to soften and decay and flowers to rot, or buds may blacken and fail to open. Leaf blotch occurs when dark purple spots form on the upper surfaces of leaves.
In ancient times, the peony was considered a medicinal plant, used to treat bladder stones, epilepsy, lunacy and stomachache, among other conditions, according to Paeonia.