Didiereaceae

Didiereaceae
	Alluaudia montagnacii
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Core eudicots
Order:	Caryophyllales
Family:	Didiereaceae; Drake del Castillo

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Didiereaceae is 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 that the genus Portulacaria (previously in Portulacaceae) is part of this family, thus extending its distribution beyond the island of Madagascar.

[edit] Description

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 shrub 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 radial 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.

[edit] Key to the genera

1	Spines in groups of 4 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