The plants are endoparasites of vines in the genus Tetrastigma (Vitaceae) and lack stems, leaves, roots, and any photosynthetic tissue.

The classification of Rafflesiaceae has been somewhat problematic due to their highly reduced vegetative parts, modified reproductive structures, and anomalous molecular evolution (Davis 2008).

In fact, Molina et al. (2014) found that a genus of Rafflesia is the first parasitic plant studied containing no recognizable remnants of the chloroplast genome.

This study showed three genera (corresponding to tribe Rafflesieae, that is, Rafflesia, Rhizanthes, and Sapria) were components of the eudicot order Malpighiales.

Thus, the group traditionally classified as a single family, Rafflesiaceae, was actually composed of at least four distinct and very distantly related clades, with their similarities due to convergent evolution under their common parasitic lifestyle.

[5] A 2007 phylogenetic analysis found strong support for Rafflesiaceae being derived from within Euphorbiaceae as traditionally circumscribed, which was surprising as members of that family typically have very small flowers.