DILLENIALES

order of dicotyledonous flowering plants comprising two families (Dilleniaceae and Paeoniaceae), with 11 genera, most of which are trees, shrubs, or woody vines of the tropics and subtropics. The plants are characterized by radially symmetrical, usually bisexual flowers with three to many (but usually five) overlapping sepals; usually five overlapping petals; numerous stamens (the male pollen-producing structures); and several separate, ovule-bearing structures (pistils), each containing an indefinitely large number of ovules that develop into seeds with a fleshy appendage (aril) attached. Each pistil is topped by a slender pollen-receptive structure (the style). The flower has a characteristic appearance from the spreading of the styles. The order is botanically significant as an evolutionary link between the more primitive magnolia order (Magnoliales) and several more advanced orders, the most immediately related of which are the tea or camellia order (Theales) and the violet order (Violales). The Dilleniaceae has a few tree species that are useful for their timber (e.g., Dillenia indica, D. parviflora, and D. pentagyna) and as a source of tannin. Several species of Hibbertia are grown as ornamentals, especially H. scandens, a woody vine with yellow, ill-smelling flowers, which is grown only in warm areas such as southern California or in greenhouses. Dillenia indica is also a greenhouse plant in temperate areas, where it is grown for its fragrant white flowers. It is a tree in its native area (Southeast Asia to Australia and Fiji), however, where it is valued for its lemon-flavoured fruits used in jellies and curries. The largest genera of the family Dilleniaceae are Hibbertia (100 species), Dillenia (60 species), Tetracera (40 species), Doliocarpus (40 species), and Davilla (38 species). The family Paeoniaceae contains only the genus Paeonia, which has 30 species of small-leaved perennial herbs or shrubs of temperate Europe and Asia, with one or two species in the western United States.