Didiereaceae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s found in continental

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

and

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. It contains 20 species classified in three subfamilies and six genera. Species of the family are

succulent plant In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meanin ...

s, growing in sub-arid to arid habitats. Several are known as

ornamental plant Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

s in specialist succulent collections. The subfamily Didiereoideae is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the southwest of Madagascar, where the species are characteristic elements of the spiny thickets.

Systematics

The family was long considered entirely endemic to Madagascar until the genera ''Calyptrotheca'', '' Ceraria'', and '' Portulacaria'' from the African mainland were included.

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

analysis confirmed the

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

of the family and its three subfamilies: The family is closely related to the

New World The term "New World" is used to describe the majority of lands of Earth's Western Hemisphere, particularly the Americas, and sometimes Oceania."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: ...

family

Cactaceae A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...

(cacti), sufficiently closely so that species of Didiereaceae can be grafted successfully on some cacti.

Calyptrothecoideae

Contains only one genus, '' Calyptrotheca'', with two species found in tropical

East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...

Didiereoideae

This subfamily is endemic to Madagascar, where it is found in the spiny thickets of the dry southwest. The plants are spiny

succulent In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s and

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s from 2–20 m tall, with thick water-storing stems and

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

that are

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

in the long

dry season The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The t ...

. All of the species except ''Alluaudiopsis'' have 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.Rauh, W. 1983. The morphology and systematic position of the Didiereaceae of Madagascar. Bothalia 14(3/4): 839–843. All species are

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

(''Decarya'' female-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 the areoles found in cacti). The flowers are unisexual (except from ''Decarya'') and radially symmetric, made up of four

tepals A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of ve ...

with two basal bracts. Flowers rarely occur singly. They usually develop in branched clusters that emerge instead of leaves from the brachyblasts. There are four genera with eleven species: '' Alluaudia'' *'' Alluaudia ascendens'' *'' Alluaudia comosa'' *'' Alluaudia dumosa'' *'' Alluaudia humbertii'' *'' Alluaudia montagnacii'' – probably a natural hybrid of ''A. ascendens'' and ''A. procera'' *'' Alluaudia procera'' – quite easy grown and the most frequent species in cultivation '' Alluaudiopsis'' *'' Alluaudiopsis fiherensis'' *'' Alluaudiopsis marnieriana'' '' Decarya'' *'' Decarya madagascariensis'' '' Didierea'' *'' Didierea madagascariensis'' *'' Didierea trollii'' Key to the genera of Didieroideae:

Portulacarioideae

Contains one genus, '' Portulacaria'', with seven species, distributed in

Southern Africa Southern Africa is the southernmost region of Africa. No definition is agreed upon, but some groupings include the United Nations geoscheme for Africa, United Nations geoscheme, the intergovernmental Southern African Development Community, and ...

. Species formerly considered in the separate genus '' Ceraria'' are now included in ''Portulacaria''.

Gallery

File:Ceraria_namaquensis_01_ies.jpg, '' Portulacaria namaquensis'' File:Jade_leaves.jpg, '' Portulacaria afra'' File:Alluaudia ascendens.JPG, ''Alluaudia ascendens'' File:Alluadia comosa Tsimanampetsotsa.jpg, ''Alluaudia comosa'' File:Alluaudia montagnacii.jpg, ''Alluaudia montagnacii'' File:Alluaudia procera2.JPG, ''Alluaudia procera''

References

{{Taxonbar, from=Q131286 Caryophyllales families Desert flora Flora of the Afrotropical realm