Peony

Paeonia suffruticosa is a name used for a group of culture varieties of tree peonies that are the result of hybridisation with species exclusively belonging to the subsection Vaginatae. The common name used in China is 牡丹 (mu dan). Plants belonging to this group have been cultivated for millennia in China, initially only as a source of traditional Chinese medicine particularly the skin of its roots is used as 牡丹皮 (mu dan pi). Already early on the plant was also cultivated for its ornamental value, and it is highly revered in Chinese culture.

Paeonia suffruticosa is the name used for most tree peony cultivars, but is not a naturally occurring species. So it can be regarded as the name for a man-made hybrid swarm. Genetic analysis has shown that five species of the subsection Vaginatae together make up the parentage of the tree peony cultivars created before World War II. In over three quarters of the almost fifty studied cultivars, the DNA of their chloroplasts is identical to that in Paeonia cathayana, indicating that this species is the original maternal parent. Almost all of the remaining cultivars has chloroplast DNA identical to that in P. qiui, and rarely from P. ostii and partially from Paeonia rotundiloba. In the nuclear DNA however, homology with Paeonia rockii is largest, with lesser contributions from P. qiui,P. ostii, P. cathayana and P. jishanensis. Paeonia decomposita is the only species from the Vaginatae that has not contributed to these cultivars.

Crossbreeding of yellow-flowered P. delavayi with traditional double-flowered P. suffruticosa cultivars by Émile Lemoine has led to the introduction of the color yellow into the cultivated double-flowered tree-peonies. These hybrids are known as the P. ×lemoinei-group, and include double-flowered "Chromatella" (1928), "Alice Harding" (1935) and semidouble-flowered "Sang Lorraine" (1939). In 1948 horticultulturist Toichi Itoh from Tokyo used pollen from "Alice Harding" to fertilize the herbaceous P. lactiflora"Katoden", which resulted in a new category of peonies, the Itoh or intersectional cultivars. These are herbaceous, have leaves like tree peonies, with many large flowers from late spring to early autumn, and good peony wilt resistance. Some of the early Itoh cultivars are "Yellow Crown", "Yellow Dream", "Yellow Emperor" and "Yellow Heaven".

Cultivated hybrid tree peonies originate from China and its surrounding areas, possessing significant cultural meaning throughout Chinese history. Currently there are about 600 Chinese tree peony cultivars. Since its introduction abroad, a few unique cultivar groups have been bred in France, Britain, the United States, and some other countries.
This species is less common in U.S, but it can generally be found in plant nurseries.

Paeonia suffruticosa belongs to the peony family. The most distinctive feature is that Paeonia suffruticosa is a bush or a tree, whereas most peonies are herbaceous. Despite their classification as trees, it is the flowers that attract people's attention. Peonies are generally slow to grow and have flowers that only last briefly and are fragile under weather conditions such as wind, rain or hot temperatures.
In comparison, Paeonia suffruticosa, as a tree, survives longer than the rest of the peonies. The woody stems of tree peonies allow the plant to survive in winter. In general, the plant is long-lived, and the flowers bloom longer in the early spring.

In order to propagate the bush, the seeds are collected in June when the seed pods split. The pods are air-dried for a few days and are then stored in moist soil before planting out during autumn. Putting the pods into moist soil gives some moisture to the pods; If the pods are fully dried out, it is more difficult for the seeds to sprout.
Ideally, the plant should be planted in fertile, humus-rich soil with plenty of organic matter (in USDA zones 3 to 8).

Paeonia suffruticosa grows in both full sun to dappled shade. However, the plant blooms best in dappled shade with 3 to 4 hours of sunlight. When grown in full sun, it is essential to provide adequate moisture to the plant.
Generally, the tree requires very little pruning, but it is necessary to cut off dead branches, and to cut off any sprouts that are suckers from the herbaceous root stock.
Potential cultivating diseases include Ca. Phytoplasma solani, the causal agent of the Black wood disease of grapevine. This is associated with tree peony yellows disease in China.

Paeonia suffruticosa has a long history of being used in Chinese medicine. There are more than 1000 Chinese tree peony cultivars with various flower colors and flower forms that have been selected artificially for medicinal uses for more than 2000 years.
The root bark, often referred to as Mu Dan Pi or Cortex Moutan, is the main part that is used in Chinese medicine. Mu Dan Pi’s main functions include reducing heat, cooling the blood, improving liver function, and mildly invigorating the blood. Mu Dan Pi of the best quality should be very fragrant, thick, white and starchy. The flower is now mostly cultivated for medicinal uses. Due to over-harvesting, the wild plant is threatened with extinction.