The subfamily Didiereoideae is endemic to the southwest of Madagascar, where the species are characteristic elements of the spiny thickets.

The family was long considered entirely endemic to Madagascar until the genera Calyptrotheca, Ceraria, and Portulacaria from the African mainland were included.

The plants are spiny succulent shrubs and trees from 2–20 m tall, with thick water-storing stems and leaves that are deciduous in the long dry season.

The flowers are unisexual (except from Decarya) and radially symmetric, made up of four tepals with two basal bracts.

[4] There are four genera with eleven species: Alluaudia (Drake) Drake 1903 Alluaudiopsis Humbert & Choux 1934 Decarya Choux 1929 Didierea Baillon 1880 Key to the genera of Didieroideae: Contains one genus, Portulacaria, with seven species, distributed in Southern Africa.