By Jovita Turan, June 27, 2021
The peony (Paeonia L,) genus, belonging to Paeoniaceae family, has more than 30 woody and herbaceous species. The plant is native to Asia, southern Europe, and western North America.
Paeonia is divided into three sections, Onaepia, Moutan, and Paeonia.
Section Moutan includes nine woody species:
P. cathayana,
P. decomposita,
P. delavayi,
P. jishanensis,
P. ludlowii,
P. ostii,
P. qiui,
P. rockii,
P. sufruticosa.
Section Paeonia has 22 species, all of which are herbaceous.
Section Onaepia has only two species:
P. brownie,
P. californica.
The peony, known as the “queen of the garden”, has great importance in many countries and continents. It is known that the peonies were cultivated in China as far as 3000 years ago. The name of the flower arising from the Greek god of medicine and healing – Paeon.
The peonies can be herbaceous or trees. Herbaceous peony had been introduced to Europe in the early 19th century, and in 1850 many American nurseries were already able to offer new cultivars of the plant. Today, the plant is considered one of the most beautiful and rewarding plants in Europe, Asia, and North America.
The woody peonies have woody stems, they can grow up to 2 meters in height and are flowering in early spring.
Herbaceous peonies are having annual stems that are arising every year from underground storage organs. Herbaceous peonies are shorter (up to 1 meter) and flowering in late spring and early summer. Above-ground shoots of the peonies senesce and die in late autumn. The low temperatures are breaking the dormancy of the underground buds and that allows them to emerge and grow in the next spring.
The flowers of the plant are large, usually fragrant, from pink and purple to red, white, or yellow. The leaves are compound and deeply lobed. The seeds of the plant are brown to black, smooth, and relatively large.
GROWING CONDITIONS AND PROPAGATION
Peonies grow well in temperate, cold-winter climatic zones, however, there are on going studies on peony cultivation development in warmer climate conditions as well. Peonies are grown as potted plants or as cut flowers.
The optimal conditions for the proper development of peony flowers were determined to be 22 C during the day and 10 C during the night. However, it is known, that high-temperature variations are common under natural growing conditions. To expand cut peony production, the grower should consider biological limitations of the peony as well as the development of production techniques for heating during cold, prolonged springs and ventilation/cooling when temperatures are too high. These techniques are helping to avoid flower abortion and foliar diseases and helping to form strong stems.
Peony propagation from seeds is not often due to complicated germination, long juvenile period, and non-uniform seedlings due to sexual reproduction.
Vegetative propagation is the most common and known method in commercial and private gardening. The peony can be propagated by crown division, green shoot cuttings, root cuttings, layering, and micropropagation.
Crown division – the most popular method. The foliage has to be cut back in late summer or late autumn, the plant has to be dug up with an intact crown and as much of the root system as possible. Then, roots have to be washed and plants have to be left in the shade for several hours. Crown division must have at least one visible crown bud to grow. However, the more buds per division the stronger plant will be.
Green shoot cutting – the method has a relatively low success rate, only about 15-20%. The method is good to use if the breeder or producer does not want to damage the crown of the plant or in the case of rare varieties. The cuttings are taken two weeks before flowering.
Root cuttings – the method that was proposed for the peony hybrids that form renewal buds on storage roots. In this case, storage roots can be divided in autumn into 1-3 cm long sections. They have to be treated with fungicides and planted in 5-6 cm deep trays that are filled with clean river water.
Layering – the method that can be used for both, herbaceous and woody peonies, where a section of the stem is forced to develop the roots while it is still attached to the mother plant. In the early spring, freshly sprouted shoots have to be gently pressed to the ground and covered with a well-drained mixture of compost and sand. The rooted shoot can be separated from the mother plant in the next late summer. Only once in 3 – 4 years, this procedure can be done using the same plant.
Micropropagation – the propagation in laboratory method that is used in several commercial companies to produce large numbers of rare peony varieties.
BIOACTIVE SUBSTANCES FOUND IN PAEONIA SPP
The peony plant contains several active compounds that include terpenoids, tannins, flavonoids, stilbenes, steroids, and phenols. Paeoniflorin and paeonol are unique and major active components that are found in the roots of Paeonia.
Common/Garden peony (P. officinalis) was reported to have several anthocyanins and one phenolic acid glycoside in the roots.
Other Paeonia spp. (P. lactiflora, P. suffruticosa) seeds contain high amounts of polyunsaturated oil and proteins for foods.
TRADITIONAL MEDICINE AND RECENT STUDIES
In traditional medicine, several Paeonia spp. have been used for treating epilepsy, diarrhea, liver diseases, and several other disorders.
In traditional Chinese medicine, the dried roots of Chinese peony (P. lactiflora) has been used as a decoction to treat headaches, dizziness, costal and abdominal pain, spasmodic pain of the limbs, anemia, menstrual disorders, spontaneous sweating, and night sweating. Moreover, peony is used to treat depression-like symptoms.
Common/Garden peony (P. officinalis) has been used as an antiepileptic and antispasmodic drug.
Recent studies are focused on essential oils and the antioxidant potentials of the root extracts. They had shown the potential of the high source of oleanolic and urolic acid. Other properties such as antitumor, anti-inflammatory, anti-microbial, immune system modulation, central nervous, and cardiovascular system protective activities were reported as well.
In the last decades the dried root of Paeoniae Alba showed effectiveness to treat rheumatoid arthritis, systemic lupus erythematosus, hepatitis, and other inflammatory/autoimmune diseases.
USAGE
The petals of peony can be added to salads, punches, and lemonades. They can be used to prepare jellies, ice cream, and/or cocktails. Dried peony roots are used as tea or blended to powder.
Peonies can be found in various cosmetics, essential oils, and blends. They can be used to make simple sugar or salt scrubs. Dried petals can be used due to their pleasant fragrance in the rooms, cars, etc.
REFERENCES
Dienaitė, L., Pukalskienė, M., Pukalskas, A., Pereira, C. V., Matias, A. A., & Venskutonis, P. R. (2019). Isolation of strong antioxidants from paeonia officinalis roots and leaves and evaluation of their bioactivities. Antioxidants, 8(8), 249.
Fan, Y., Wang, Q., Dong, Z., Yin, Y., da Silva, J. A. T., & Yu, X. (2020). Advances in molecular biology of Paeonia L. Planta, 251(1), 1-47.
He, D. Y., & Dai, S. M. (2011). Anti-inflammatory and immunomodulatory effects of Paeonia lactiflora Pall., a traditional Chinese herbal medicine. Frontiers in pharmacology, 2, 10.
Kamenetsky, R., & Dole, J. (2012). Herbaceous peony (Paeonia): genetics, physiology and cut flower production. Floric. Ornam. Biotechnol, 6, 62-77.
Yang, Y., Sun, M., Li, S., Chen, Q., da Silva, J. A. T., Wang, A., ... & Wang, L. (2020). Germplasm resources and genetic breeding of Paeonia: a systematic review. Horticulture Research, 7(1), 1-19.
Zhang, W., & Dai, S. M. (2012). Mechanisms involved in the therapeutic effects of Paeonia lactiflora Pallas in rheumatoid arthritis. International immuno