Didiereaceae
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The Didiereaceae is a family in the order of the carnation-like (Caryophyllales) within the flowering plants . While the old family with four genera only occurs in Madagascar , the newly added three genera are common in Southern Africa and East Africa. Few species are used as ornamental plants .
description
Vegetative characteristics
They form succulent , thick- stemmed shrubs or trees with an often cactus-like habit, sometimes at a youth stage with sprawling, prostrate branches before a dominant trunk is formed. The branches are initially long shoots , in whose leaf axils short shoots develop. The leaves appear together with conical to needle-like thorns from areoles , which sometimes stand on spirally arranged warts. Portulacarioideae are not reinforced. The leaves of the long shoots are usually small and decrepit, the cross- opposite leaves of the short shoots last a growing season . Since the branches are also green, the plants can photosynthesize even when they are leafless (all species with a CAM mechanism ).
Generative characteristics
The inflorescences formed from the areoles branch out in a forked or umbel-like manner . Calyptrotheca and Portulacaria have only hermaphrodite flowers, Decarya has female and hermaphrodite flowers. In all other genera are unisexual and the species are dioecious separately sexed ( diocesan ), in Decarya female-dioecious. The relatively small flowers have a double perianth . The only two sepals are free and often unequal. The four petals in Didiereoideae and five in the other subfamilies are mostly free or fused with Portulacaria . The male flowers in Didiereoideae contain two circles with four or five each, in Ceraria one circle with five free stamens , in Portulacaria usually four to seven, rarely up to ten stamens grown together with the flower envelope, in Calyptrotheca many free stamens and a rudiment of the ovary . In the female flowers two or four carpels an upper continuous, single-chamber are usually three rare ovary grown with a long pencil , which in mostly three, rarely two or four-lobed scars ends.
The dry and more or less triangular capsule fruit is surrounded by the perennial pair of sepals and contains only one seed.
The chromosome numbers in the Didiereoideae are 2n = 48, 192, 240, in the Calyptrothecoideae they are not known and in the Portulacarioideae 2n = 44, 48, 72.
use
Some species are kept as ornamental plants . The most common representatives in collections of succulent plants are the bacon tree, money tree, penny tree, elephant tree, bush purslane, jade tree ( Portulacaria afra ), alluaudia procera is much less common .
Systematics and distribution
Only the subfamily Didieroideae, not the Didiereaceae family, occurs only in Madagascar and its species thrive in seasonally very dry thorn forests in the south and southwest of the island. The three other genera are native to Southern Africa and East Africa.
External system
It turned out by molecular genetic studies that the Portulacaceae were paraphyletic and in a common clade with the Didiereaceae s. st. stood and together made a monophyletic family. Within the order of the Caryophyllales , the Didiereaceae are related to the Halophytaceae , Basellaceae , Montiaceae and the clade from Talinaceae , Portulacaceae , Anacampserotaceae and Cactaceae .
The Didiereaceae are relatively closely related to the cactus family (Cactaceae). With these the Didiereaceae share the peculiarity of having areoles . That is why the Didiereaceae are sometimes called the "cacti of the old world ". Plants of the Didiereaceae can also be grafted onto plants of the more original cactus genera Pereskia and Pereskiopsis .
The purslane family (Portulacaceae) are also closely related . According to the research results of Wendy L. Applequist and Robert S. Wallace 2001, 2003, because of the particularly close relationship of the African genera Calyptrotheca , Ceraria and Portulacaria , it was proposed to include them among the Didiereaceae.
Internal system
The valid first publication of the family name Didiereaceae took place in 1896 by Ludwig Adolph Timotheus Radlkofer in The Natural Plant Families , 3, 5, p. 462; the publication of Emmanuel Drake del Castillo in Bull. Mus. Hist. Nat. (Paris) , 9, 36 did not take place until 1903. The type genus is Didierea Baill.
The family used to consist of four genera with a total of eleven species .
Since 2003 the family has been divided into three subfamilies, comprising the following seven genera with around 15 species (as of 2010):
- Subfamily Calyptrothecoideae Appleq. & RSWallace : It contains only one genus:
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Calyptrotheca Gilg : There are roughly two species that are common in tropical East Africa:
- Calyptrotheca somalensis Gilg : It is distributed from southern Ethiopia through southern Somalia to northern Kenya.
- Calyptrotheca taitensis (Pax & Vatke) Brenan : It is distributed from Somalia via Kenya to Tanzania .
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Calyptrotheca Gilg : There are roughly two species that are common in tropical East Africa:
- Subfamily Portulacarioideae Appleq. & RSWallace : There are two genera in southern Africa:
- Ceraria Pearson & Stephens : The sixor sospecies are common in Namibia and South Africa. However, some authors place them on portulacaria .
- Portulacaria Jacq. : The two to seven species are common in southern Africa .
- Subfamily Didiereoideae Appleq. & RSWallace : The four genera occur only in Madagascar:
- Alluaudia (Drake) Drake : The approximately six species occur only in southern and southwestern Madagascar.
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Alluaudiopsis Humbert & Choux : There are two types:
- Alluaudiopsis fiherensis Humbert & Choux : It occurs in Madagascar only in the province of Toliara .
- Alluaudiopsis marnieriana Rauh : It occurs in Madagascar only in the province of Toliara.
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Decarya Choux : It contains only one species:
- Decarya madagascariensis Choux : It occurs in Madagascar only in the province of Toliara.
- Didierea Baill. : There are two types that occur in Madagascar.
swell
- The family of Didiereaceae in APWebsite. (engl.)
- The Didiereaceae family in the old range at DELTA. (engl.)
- Wendy L. Applequist, Robert S. Wallace: Expanded circumscription of Didiereaceae and its division into three subfamilies . In: Adansonia 3rd episode, volume 25, number 1, 2003, pp. 13–16: (PDF; 82 kB) .
literature
- Werner Rauh : Didieréacées - 121e famille , in H. Humbert (Ed.): Flore de Madagascar et des Comores , Muséum National d'Histoire Naturelle, 1963.
- Werner Rauh: The Didiereaceae , in Ashingtonia , 2, 1975. 2-5
- Gordon D. Rowley : Didiereaceae "Cacti of the Old World" , British Cactus and Succulent Society, 1992.
Individual evidence
- ^ Didiereaceae at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ Wendy L. Applequist, Robert S. Wallace: Expanded circumscription of Didiereaceae and its division into three subfamilies . In: Adansonia 3rd volume, volume 25, number 1, 2003, pp. 13-16
- ^ Didiereaceae at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed January 30, 2015.
- ↑ Wendy L. Applequist, Robert S. Wallace: Expanded circumscription of Didiereaceae and its division into three subfamilies . In: Adansonia 3rd volume, volume 25, number 1, 2003, pp. 13-16
- ↑ Reto Nyffeler, Urs Eggli: Disintegrating Portulacaceae: A new familial classification of the suborder Portulacineae (Caryophyllales) based on molecular and morphological data. In: Taxon . Volume 59, Number 1, 2010, pp. 227-240.
- ↑ a b c d e Rafaël Govaerts (ed.): Didiereaceae. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved September 19, 2017.
- ↑ a b c d e f g h Didiereaceae at Tropicos.org. In: Catalog of the Vascular Plants of Madagascar . Missouri Botanical Garden, St. Louis
