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The Didiereaceae are a small family of just four genera and 11 species of flowering plants endemic to south and southwest Madagascar, where they form an important component of the Madagascar spiny forests. Molecular studies have shown the genus Portulacaria (previously in Portulacaceae) is part of this family, thus extending its distribution beyond the island of Madagascar.
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. Some species build a distinct youth form as small procumbent shrubs before a dominant stem is produced.
All species are dioecious (Decaria female-dioecious). The leaves, produced from areoles like in cacti, are small, appear single or in pairs and are accompanied by conical spines. The flowers are unisexual (except from Decaria) and radially symmetric.
The family is sometimes included within the Portulacaceae, but is treated as distinct by the Angiosperm Phylogeny Group. It is also closely related to the New World family Cactaceae (cacti), sufficiently closely so that the species of Didiereaceae can be grafted successfully on some cacti.
Key to the genera
|1||Spines in groups of four or more:||Didierea|
|-||Spines single or in pairs:||→ 2|
|2||Shoots striking zigzagged, spines short conical:||Decarya|
|-||Shoots not zigzagged, spines long conical to needle-like:||→ 3|
|3||Shrubs strongly branched, leaves lanceolate:||Alluaudiopsis|
|-||Shrubs little branched, leaves either ovate to circular or scale-like and awl-shaped:||Alluaudia|
Genera and species
- Alluaudia ascendens (Drake) Drake 1903
- Alluaudia comosa (Drake) Drake 1903
- Alluaudia dumosa (Drake) Drake 1903
- Alluaudia humbertii Choux 1934
- Alluaudia montagnacii Rauh 1961 – probably a natural hybrid of A. ascendens and A. procera
- Alluaudia procera (Drake) Drake 1903 – quite easy grown and the most frequent species in cultivation
Several of the species are grown as indoor ornamental plants in specialist succulent collections.
- Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013–06–26.
- Eggli, Urs (Ed.): Sukkulentenlexikon Band 2: Zweikeimblättrige Pflanzen (Dicotyledonen) Eugen Ulmer Verlag, Germany 2002. ISBN 3-8001-3915-4