Ancient Chinese texts mention the peony was used for flavoring food. Peonies have been used and cultivated in China since early history. Ornamental cultivars were created from plants cultivated for medicine in China as of the sixth and seventh century. Peonies became particularly popular during the
Tang dynasty, when they were grown in the imperial gardens. In the tenth century the cultivation of peonies spread through China, and the seat of the
Song dynasty,
Luoyang, was the centre for its cultivation, a position it still holds today. A second centre for peony cultivation developed during the
Qing dynasty in Cáozhōu, now known as
He Ze. Both cities still host annual peony exhibitions and state-funded peony research facilities. Before the tenth century,
P. lactiflora was introduced in Japan, and over time many varieties were developed both by
self fertilisation and
crossbreeding, particularly during the eighteenth to twentieth centuries (middle
Edo to early
Shōwa periods). During the 1940s Toichi Itoh succeeded in crossing tree peonies and herbaceous peonies and so created a new class of so-called
intersectional hybrids. Although
P. officinalis and its cultivars were grown in Europe from the fifteenth century on, originally also for medicinal purposes, intensive breeding started only in the nineteenth century when
P. lactiflora was introduced from its native China to Europe. The tree peony was introduced in Europe and planted in
Kew Gardens in 1789. The main centre of peony breeding in Europe has been in the United Kingdom, and particularly France. Here, breeders like
Victor Lemoine and François Félix Crousse selected many new varieties, mainly with
P. lactiflora, such as "Avant Garde" and "Le Printemps". The Netherlands is the largest peony cut flower producing country with about 50 million stems each year, with "Sarah Bernhardt" dominating the sales with over 20 million stems.
Plant growth habits While the peony takes several years to re-establish itself when moved, it blooms annually for decades once it has done so. Peonies tend to attract
ants to the flower buds. This is due to the nectar that forms on the outside of the flower buds, and is not required for the plants' own pollination or other growth. The presence of ants is thought to provide some deterrence to other harmful insects though, so the production of ant-attracting nectar is plausibly a functional
adaptation. Ants do not harm the plants. Peony species come in two distinct growth habits, while hybrid cultivars in addition may occupy an intermediate habit. •
herbaceous: During summer, renewal buds develop on the underground stem (the "crown"), particularly at the foot of the current season's annual shoots. These renewal buds come in various sizes. Large buds will grow into stems the following growing season, but smaller buds remain dormant. The
primordia for the leaves can already be found in June, but the flower only starts differentiating in October, as the annual shoots die down, completing its development in December, when sepals, petals, stamens and pistils are all recognisable. •
tree: During the summer, large buds develop at the tip of the annual growth and near its foot. In the autumn, the leaves are shed, and the new stems become woody and are perennial. •
Itoh (or "Intersectional"): In 1948 horticulturist Toichi Itoh from Tokyo used pollen from the yellow tree peony "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".
Flower types Seven types of flower are generally distinguished in cultivars of herbaceous peonies. •
single: a single or double row of broad petals encircle fertile stamens, carpels visible. •
Japanese: a single or double row of broad petals encircle somewhat broadened
staminodes, may carry pollen along the edges, carpels visible. •
anemone: a single or double row of broad petals encircle narrow incurved petal-like staminodes; fertile stamens are absent, carpels visible. •
triple: the flower consists of triple row of broad petals that broaden and overlap each other. •
semi-double: a single or double row of broad petals encircles further broad petals intermingled with stamens. •
bomb: a single row of broad petals encircles a shorter dense pompon of narrower petals. •
double: the flower consists of many broad petals only, including those which likely are altered stamens and carpels. Herbaceous peonies such as
Paeonia lactiflora, will die back to ground level each autumn. Their stems will reappear the following spring. However tree peonies, such as
Paeonia suffruticosa, are shrubbier. They produce permanent woody stems that will lose their leaves in winter but the stem itself remains intact above ground level.
Cultivars The numerous peony hybrids and
cultivars have gained the
Royal Horticultural Society's
Award of Garden Merit, including: • 'Bartzella', a double yellow-flowered Itoh (intersectional) peony • 'Coral Charm', a
semi-double salmon-pink-flowered herbaceous peony •
Paeonia ×
festiva 'Rubra Plena', a
bomb red-flowered herbaceous peony •
Paeonia ×
lemoinei 'High Noon', a semi-double yellow-flowered tree peony The American Peony Society is the
International Cultivar Registration Authority for the genus, and accepts over 7,000 registered cultivars. == Uses ==