The genus Paeonia, sole representative of the family Paeoniaceae, is widely distributed around the northern hemisphere from southern Europe through Eurasia into China, Japan and western North America. Despite comprising only about thirty species, the large, vivid Paeonia blooms are familiar in gardens, botanical art and the cut-flower trade.
Peonies are perennials with characteristically divided leaves, and have two growth forms. Herbaceous peonies, with their fleshy roots, produce two types of buds on the surface of an underground stem during the summer months. When the large buds burst, stems grow; the small buds remain dormant. By the time the large buds break in the spring, flower buds have already formed. In the case of tree peonies, which are deciduous, soft-wood shrubs, buds form at the tips and bases of the annual growth which overwinters. Horticulturalists have created popular artificial hybrids between these two different growth forms.
Paeonia flowers usually have five red, white or yellow petals, a ring of numerous stamens and, at their centres, a few free carpels. As peony fruits mature, they dry before splitting open along one side to reveal a small number of large black seeds; these usually have brightly coloured, fleshy outgrowths. Traditionally, the features of the flower and fruit have contributed to the belief that Paeonia is related to the buttercups. DNA analyses challenge this view, showing the genus is related to the saxifrages.
In China, peonies, particularly Paeonia lactiflora, have been cultivated, bred and selected for millennia for the form and colour of their flowers, and the supposed medicinal properties of their seeds and roots. The European vogue for Chinese culture in the nineteenth century, together with the arrival of Asian peony species to augment those already known from southern Europe and North Africa, stimulated interest in the genus among the continent’s horticulturalists. The result was a surge in peony breeding and cultivar production.
Medicinal use of peonies is not an Asian phenomenon. Native Americans used New World species, whilst European medicinal use is reflected in the plant’s generic name (Paeon was physician to the Ancient Greek gods). Early modern European herbals are replete with stories and peony-based cures based on ancient authority. Moreover, the scientific name Paeonia officinalis is a relic of the species’ use as an officinal, i.e., a drug recommended by official bodies of physicians for use in pharmacopoeias. There is no modern scientific evidence peony has any medicinal value.
Halda JJ and Waddick JW 2004. The genus Paeonia. Timber Press.
Hong DY 2010. Peonies of the world: taxonomy and phytogeography. Kew Publishing.
Hong DY 2011. Peonies of the world: polymorphism and diversity. Kew Publishing.