Paeonia L. — the peonies — is a genus of about 33 accepted species of herbaceous perennials and deciduous shrubs in the monogeneric family Paeoniaceae, placed in the order Saxifragales. Herbaceous species typically grow 25–100 cm tall, while the woody "tree peonies" reach up to 3.5 m. All members share thick, fleshy storage roots and large, compound leaves without glands or stipules. The flowers are among the most spectacular in the temperate garden: bisexual, usually solitary at the stem tip, with 3–7 sepals, 5–8 (occasionally up to 13) free petals, 50–160 stamens, and 1–15 separate pistils. Colors span deep purple and crimson through pink and white to yellow, and individual flowers last 7–10 days in late spring to early summer.
The genus is native to Asia, Europe, and western North America. Section Moutan (the tree peonies) is confined to central and southern China including Tibet. Section Onaepia comprises just two herbaceous species restricted to western North America — Paeonia brownii from southern British Columbia south to California and east to Wyoming, and P. californica along the coastal ranges of southern and central California. The large Section Paeonia spans a broad band from Morocco and Spain eastward to Japan and includes species in Mediterranean islands, central Asia, the Himalayas, Siberia, and the Russian Far East; P. anomala holds the largest individual range, stretching from the Kola Peninsula to Lake Baikal.
In the wild, peonies occupy habitats ranging from coniferous woodland and rocky hillsides with scrub to dry steppe grassland. Peonies use C3 carbon fixation, and extrafloral nectaries on the flower buds attract ants that provide some protection against herbivorous insects. Plants are long-lived once established, tolerating temperatures to -25°C and persisting for 50 years or more in garden conditions.
Peonies have been cultivated in China since at least the 6th and 7th centuries, and P. lactiflora was introduced to Japan before the 10th century. Today the Netherlands is the world's largest producer of peony cut flowers, with approximately 50 million stems per year. The family name Paeoniaceae was first formally applied by Friedrich K.L. Rudolphi in 1830, though the genus itself was established by Linnaeus in his 1753 Species Plantarum, where P. officinalis serves as the type species.
Etymology
The genus name Paeonia (and its English derivative "peony" or "paeony") traces to Greek mythology. The name refers to Paeon, the physician of the gods in Greek legend who used the plant medicinally. Linnaeus formalised the latinised form Paeonia in 1753. The English pronunciation is /ˈpiːəni/.
Distribution
Paeonia is native to temperate and montane regions of Asia, Europe, and western North America. The three sections each occupy a distinct phytogeographic range. Section Moutan (tree peonies) is restricted to central and southern China, including Tibet. Section Onaepia comprises two species in the American West: P. brownii, ranging from southern British Columbia south through the Sierra Nevada and east to Wyoming and Utah, and P. californica, confined to the coastal mountains of southern and central California. Section Paeonia, the largest group, extends in a broad band from Morocco and Spain eastward through the Mediterranean basin (including Corsica, Sardinia, Sicily, Crete, and Rhodes), across central Asia and the Caucasus, through the Himalayas to Manchuria, Korea, Japan, and the Russian Far East and Siberia. P. anomala has the widest individual range of any species, from the Kola Peninsula in northwestern Russia to Lake Baikal. P. lactiflora is native to northern China, Manchuria, Japan, Korea, Mongolia, and Siberia. P. emodi is restricted to the western Himalayas between Pakistan and western Nepal. In the Arizona–New Mexico flora region of North America, only P. brownii and P. californica are native; P. lactiflora, P. officinalis, and P. suffruticosa occasionally escape from cultivation.
Ecology
Peonies inhabit coniferous woodland, rocky hillsides with scrub, and dry steppe grassland across their natural range in Europe and central Asia. All species use C3 carbon fixation. The flower buds produce extrafloral nectar that attracts ants, which are thought to deter harmful insects from the developing flowers. Plants establish slowly from seed or division but, once settled, persist for decades — individuals can survive 50 years or more in garden conditions. Peonies strongly resist root disturbance and do not readily produce new buds if the growing tip of a shoot is removed. Growth of nearby plants, especially legumes, can be suppressed by competitive peonies.
Cultivation
Peonies have been cultivated in China since at least the 6th and 7th centuries and were introduced to Japan before the 10th century. They require deep, rich soil — ideally neutral to slightly alkaline — and perform well in full sun or light shade. They are cold-hardy to approximately -25°C (USDA zones 4–8). Once established, peonies bloom reliably every year for many decades, but they are slow to re-establish after transplanting and should be disturbed as little as possible. They are not generally browsed by deer or rabbits. The Netherlands is the global leader in peony cut-flower production, supplying around 50 million stems annually.
Propagation
Herbaceous peonies and Itoh (intersectional) hybrids are most commonly propagated by root division in spring or autumn, with each division needing at least one healthy leaf bud. Seed propagation is possible but slow: fresh seed germinates roots within about six weeks, with aerial shoots emerging the following spring, while stored seed may take 18 months or more and is best started in pots for two full growing seasons before transplanting. Tree peonies are typically propagated by root grafting in commercial production, though division, cuttings, and seed are also used. Growth of peonies from seed to first bloom generally takes 4–5 years.
Cultural Uses
The peony has deep cultural significance across Asia and Europe. In China it is known as fùguìhuā (富貴花), meaning "flower of riches and honour," and has been a symbol of prosperity, good fortune, and feminine beauty for over a thousand years. The Qing dynasty formally declared the peony China's national flower in 1903. The root of P. lactiflora is one of the most frequently used herbs in the traditional medicines of China, Korea, and Japan. Its active compound paeoniflorin has demonstrated antispasmodic effects on intestinal smooth muscle and is reported to reduce blood pressure, fever, and stress-induced ulceration. Dried petals have been used as treatments for coughs, hemorrhoids, and varicose veins. In China, fallen petals of P. lactiflora are also parboiled and sweetened as a tea-time food.
In Japan, P. suffruticosa is called the "King of Flowers" and P. lactiflora the "Prime Minister of Flowers." Peonies feature prominently in Japanese tattoo culture, widely popularised through the woodblock prints of ukiyo-e artist Utagawa Kuniyoshi. Indiana, USA, designated the peony as its official state flower in 1957. In Serbian folklore, P. peregrina is said to represent the blood of Serbian warriors who fell at the Battle of Kosovo.
Taxonomy
Paeonia L. was formally established by Carl Linnaeus in Species Plantarum (1753), with Paeonia officinalis designated as the type species. The family Paeoniaceae was first applied by Friedrich K.L. Rudolphi in 1830. Molecular phylogenetic studies overturned earlier placements of the genus near Glaucidium in Ranunculaceae, firmly placing it in the order Saxifragales. Species-count estimates in the literature range from 25 to 40; current consensus recognises approximately 33 accepted species, though GBIF records 116 total taxa (species and infraspecific ranks combined).
The genus is divided into three sections. Section Moutan contains the woody tree peonies of China; subsection Delavayanae includes P. delavayi and P. ludlowii, while subsection Vaginatae includes P. cathayana, P. decomposita, P. jishanensis, P. ostii, P. qiui, and P. rockii. Section Onaepia holds two herbaceous North American species. Section Paeonia contains all remaining herbaceous species, characterised by complicated reticulate evolution — roughly half are tetraploid (4n=20) rather than diploid, and many Mediterranean taxa are hybrids of eastern Asian progenitors. Paeonia suffruticosa, the most widely grown tree peony, is itself a cultivated hybrid swarm rather than a naturally occurring species.
