Herbs, fleshy, parasitic on roots, stems, or branches of various hosts. Vegetative body thalloid or reduced to myceliumlike tissue within host. Normal leaves absent. Inflorescences terminal, usually 1-flowered, rarely a spike; bracts scale-like, several at base of inflorescence. Flowers usually unisexual (plants dioecious or monoecious), bisexual in Mitrastemon, actinomorphic, minute to extremely large [Rafflesia arnoldii R. Brown of Indonesia (Sumatra) produces a flower to 7.5 kg and to 1 m in diam.], 4-10-merous. Perianth lobes well-developed or absent, basally connate, rarely free. Stamens 5 to very numerous, in 1-3 series, fused with the rudimentary pistil into a gynostemium or in bisexual flowers connate into a cylinder; free filaments absent; anthers 2-loculed, dehiscent longitudinally or by apical pores. Ovary superior, semisuperior, or inferior, absent in male flowers, 1-loculed with many parietal placentas; ovules numerous, anatropous, integuments 1 or 2. Style 1 or none; stigma discoid, capitate, or with many lobes. Fruit a berry. Seeds minute, very numerous; testa hard; endosperm present.
Eight genera and 27 species: mostly in tropical and subtropical regions; two genera and two species in China.
The family is poorly represented in herbaria.
Wu Te-lin. 1988. Rafflesiaceae. In: Kiu Hua-shing & Ling Yeou-ruenn, eds., Fl. Reipubl. Popularis Sin. 24: 246–249.