Didiereaceae

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

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.

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.

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

Genera and species

Alluaudia (Drake) Drake 1903

• 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

Alluaudiopsis Humbert & Choux 1934

• Alluaudiopsis fiherensis Humbert & Choux 1934
• Alluaudiopsis marnieriana Rauh 1961

Decaria Choux 1929

• Decaria madagascariensis Choux 1929

Didierea Baillon1880

• Didierea madagascariensis Baillon 1880
• Didierea trollii Capuron & Rauh 1961

Several of the species are grown as indoor ornamental plants in specialist succulent collections.

Gallery

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  Alluaudia ascendens

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  Alluaudia montagnacii

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  Alluaudia procera, detail

Literature

• Eggli, Urs (Ed.): Sukkulentenlexikon Band 2: Zweikeimblättrige Pflanzen (Dicotyledonen) Eugen Ulmer Verlag, Germany 2002. ISBN 3-8001-3915-4