Didiereaceae
| Didiereaceae | |
|---|---|
| |
| Alluaudia montagnacii | |
Scientific classification
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Caryophyllales |
| Family: | Didiereaceae Radlk.[1] |
| Subfamilies | |
Didiereaceaeis afamilyofflowering plantsfound in continentalAfricaandMadagascar. It contains 20 species classified in three subfamilies and six genera. Species of the family aresucculent plants,growing in sub-arid to arid habitats. Several are known asornamental plantsin specialist succulent collections. The subfamily Didiereoideae isendemicto the southwest of Madagascar, where the species are characteristic elements of thespiny thickets.
Systematics
[edit]The family was long considered entirely endemic to Madagascar until the generaCalyptrotheca,Ceraria,andPortulacariafrom the African mainland were included.[2]Molecular phylogeneticanalysis confirmed themonophylyof the family and its three subfamilies:[3]
| Didiereaceae |
| ||||||||||||
The family is closely related to theNew WorldfamilyCactaceae(cacti), sufficiently closely so that species of Didiereaceae can begraftedsuccessfully on some cacti.[3]
Calyptrothecoideae
[edit]Contains only one genus,Calyptrotheca,with two species found in tropicalEast Africa.[3]
Didiereoideae
[edit]This subfamily is endemic to Madagascar, where it is found in thespiny thicketsof the dry southwest. The plants arespinysucculentshrubsandtreesfrom 2–20 m tall, with thick water-storing stems andleavesthat aredeciduousin the longdry season.All of the species exceptAlluaudiopsishave a distinct youth form. They start as small procumbent shrubs but eventually a dominant stem is produced that becomes a trunk. The trunk later branches forming a crown and the basal branches die off.[4]All species aredioecious(Decaryafemale-dioecious). The plants have different long-shoots and short-shoots (brachyblasts). Long-shoot leaves are soon deciduous, but brachyblasts form in the leaf axils and from them grow small leaves that appear singly or in pairs and are accompanied by conical spines (much like theareolesfound incacti). The flowers are unisexual (except fromDecarya) and radially symmetric, made up of fourtepalswith two basal bracts. Flowers rarely occur singly. They usually develop in branched clusters that emerge instead of leaves from the brachyblasts.[4]
There are four genera with eleven species:
- Alluaudia ascendens(Drake)Drake1903
- Alluaudia comosa(Drake)Drake1903
- Alluaudia dumosa(Drake)Drake1903
- Alluaudia humbertiiChoux1934
- Alluaudia montagnaciiRauh1961– probably a natural hybrid ofA. ascendensandA. procera
- Alluaudia procera(Drake)Drake1903– quite easy grown and the most frequent species in cultivation
AlluaudiopsisHumbert&Choux1934
Key to the genera of Didieroideae:
| 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 |
Portulacarioideae
[edit]Contains one genus,Portulacaria,with seven species, distributed inSouthern Africa.Species formerly considered in the separate genusCerariaare now included inPortulacaria.[3]
Gallery
[edit]-
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Alluaudia ascendens -
Alluaudia comosa -
Alluaudia montagnacii -
Alluaudia procera
References
[edit]- ^Angiosperm Phylogeny Group (2009)."An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III".Botanical Journal of the Linnean Society.161(2): 105–121.doi:10.1111/j.1095-8339.2009.00996.x.hdl:10654/18083.
- ^Applequist, Wendy L.; Wallace, Robert S. (2003)."Expanded circumscription of Didiereaceae and its division into three subfamilies"(PDF).Adansonia.25(1): 13–16.ISSN1280-8571.
- ^abcdBruyns, Peter V.; Oliveira-Neto, Mario; Melo-de-Pinna, Gladys Flavia; Klak, Cornelia (2014)."Phylogenetic relationships in the Didiereaceae with special reference to subfamily Portulacarioideae".Taxon.63(5): 1053–1064.doi:10.12705/635.36.ISSN0040-0262.
- ^abRauh, W. 1983. The morphology and systematic position of the Didiereaceae of Madagascar. Bothalia 14(3/4): 839–843.
