Tree peonies (Paeonia suffruticosa) are woody-stemmed shrubs that grow taller than their more common herbaceous counterparts (P. lactiflora). They produce large blooms with bright, ruffled, taffeta-like petals. Even a lone flower makes a striking table centerpiece; simply insert it in a small vase or goblet filled with room-temperature water. A grouping of several flowers, each in an individual vase, also looks lovely on a table.
When arranging tree peonies, Martha also likes to use a footed compote, in which she inserts a frog with rigid prongs. To avoid scratches in a glass container, wrap the bottom of a metal frog in plastic wrap; you may also wish to apply floral clay around the perimeter of the frog to hold it in place. Then you only need to insert a handful of tree peonies to create a lush arrangement.
Martha also places peonies in a Japanese vase (hers, fittingly, happens to be painted with peonies). Since the vase is sphere-shaped with a relatively small mouth, the tree peonies stay in position without a frog.