Dillenia is a genus of evergreen or semi-evergreen trees and shrubs in the flowering plant family Dilleniaceae, native to tropical and subtropical regions of southern Asia, Australasia, and the Indian Ocean islands.
The genus is named after the German botanist Johann Jacob Dillenius.
The leaves are simple and spirally arranged. They are generally large, in the case of Dillenia reticulata reaching in length and about wide. The flowers are solitary, or in terminal racemes, with five sepals and five petals, numerous stamens (up to 900 in the case of Dillenia ovalifolia), and a cluster of five to 20 carpels. Some species, such as Dillenia indica and Dillenia megalantha can have flower diameters of . They are superficially similar in appearance to Magnolia flowers.
, Plants of the World Online recognises the following 60 species: