A plant genus of the family Paeoniaceae, order Dilleniales, subclass Dilleniidae, class Magnoliopsida. These perennial herbs are up to 2 m (6') tall. Leaves are alternate and are divided into three lobes, each lobe being further divided into three smaller lobes. The large flowers are symmetrical, bisexual, have 5 sepals, 5 petals (sometimes 10), and many stamens.