[2] This plant is a spiny succulent shrub, with thick water-storing stems and leaves that are deciduous in the long dry season.

Although strikingly similar in appearance, it is not closely related to the ocotillo, Fouquieria splendens of the Sonoran Deserts in North America.

Like other members of family Didiereaceae, the leaves of Alluaudia, produced from brachyblasts similar to the areoles found in cacti, are small, appear single and are accompanied with conical spines.

Based on molecular phylogeny conducted[4] Alluaudia, Alluaudiopsis, and Didierea from the family are all supported as monophyletic.

However, the nearest relative of the Didiereaceae, Calyptrotheca somalensis, is endemic to East Africa,[5] from which the island of Madagascar separated 100 million years ago.