The peony or paeony is a flowering plant in the genus Paeonia , the only genus in the family Paeoniaceae . Peonies are native to Asia, Europe and Western North America. Scientists differ on the number of species that can be distinguished, ranging from 25 to 40, although the current consensus is 33 known species. The relationships between the species need to be further clarified.

Most are herbaceous perennial plants 0.25–1 metre (1–3 ft) tall, but some are woody shrubs 0.25–3.5 metres (1–11 ft) tall. They have compound, deeply lobed leaves and large, often fragrant flowers, in colors ranging from purple and pink to red, white or yellow, in late spring and early summer. The flowers have a short blooming season, usually only 7–10 days.

Peonies are popular garden plants in temperate regions. Herbaceous peonies are also sold as cut flowers on a large scale, although generally only available in late spring and early summer.