Paeonia decomposita is a little-known tree peony, which grows to a height of up to. Stems grow up to in diameter. Bark is dark grey, with a tendency to peel or flake. Flowers grow singly at the ends of the stems, and are large and usually rose-pink in colour. Follicles are dark brown or black when mature, with glossy black seeds. The shrub flowers from April to May in China.