Most are herbaceous perennial plants 1.5 - 5 feet (0.5 - 1.5 metres) tall, but some resemble trees up to 5 - 10 feet (1.5 – 3 metres) tall. They have compound, deeply lobed leaves, and large, often fragrant flowers, ranging from red to white or yellow, in late spring and early summer.

Name: The peony is named after Paeon (also spelled Paean), a student of Asclepius, the Greek god of medicine and healing. Asclepius became jealous of his pupil; Zeus saved Paeon from the wrath of Asclepius by turning him into the peony flower.

The family name "Paeoniaceae" was first used by Friedrich K.L. Rudolphi in 1830, following a suggestion by Friedrich Gottlieb Bartling that same year. The family had been given other names a few years earlier. The composition of the family has varied, but it has always consisted of Paeonia and one or more genera that are now placed in Ranunculales. It has been widely believed that Paeonia is closest to Glaucidium, and this idea has been followed in some recent works. Molecular phylogenetic studies, however, have demonstrated conclusively that Glaucidium belongs in Ranunculaceae, but that Paeonia belongs in the unrelated order Saxifragales.