Didiereaceae

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Didiereaceae
Alluaudia montagnacii
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Caryophyllales
Family: Didiereaceae
Radlk.[1]

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.

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 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. (There is a degree of confusion on this in Wikipedia articles: The above statement must be questioned. It is not clear whether Portulacaria is in this family as stated on the Portulacaceae page or whether this family is split off from Portulacaceae as a separate family as just stated. The key to genera below does not include Portulacaria so minimally this article needs editing by a specialist)

The family 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 (Drake) Drake 1903

Alluaudiopsis Humbert & Choux 1934

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

Decaria Choux 1929

  • Decaria madagascariensis Choux 1929

Didierea Baillon1880

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

Gallery

  • Alluaudia ascendens

  • Alluaudia montagnacii

  • Alluaudia procera, detail

References

  1. ↑ 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. 

Literature

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