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Aizoaceae (vygie,
mesem family)
[= Mesembryanthemaceae]
Life
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> Eudicotyledons > Core Eudicots > Order: Caryophyllales
Worldwide there are about 1854 species in 135 genera in
the family Aizoaceae, and 96% of these species are found in southern Africa
(1782 species in 132 genera in southern Africa). The vast majority of species
are succulents, falling in the previously recognised family Mesembryanthemaceae and loosely termed mesems. The arid regions of southern Africa have been the centre
of speciation for mesems and have given rise to a huge array of forms, including
flat disk-like species that look like stones.
There has been controversy over a long period about
whether the Mesembryanthemaceae should be included in the Aizoaceae or kept as a
separate family. The Aizoaceae is interpreted here in the broad sense to include
the mesems and follows the conclusions of the Angiosperm
Phylogeny Group. The reasoning behind combining the mesems in the
Aizoaceae is that evidence suggests that they are derived from this family and
to keep them in a separate family would make them paraphyletic.
In the classification below, the old
Mesembryanthemaceae family is relegated to 2 subfamilies
under the Aizoaceae: the Mesembryanthemoideae and the Ruschioideae. The
remaining subfamilies (Aizooideae, Sesuvioideae and Tetragonioideae) fall
under Aizoaceae in its strict sense.
Genera native or naturalised in southern Africa
Subfamily: Aizooideae
Acrosanthes The 5 species
are endemic to the Western Cape. |
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Aizoanthemum The
4
species are endemic to Namibia. |
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Aizoon About 25
species worldwide (mainly in the Mediterranean region) of which 11 species
are found in southern Africa. |
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Galenia About 30
species, all endemic to southern Africa. |
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Plinthus About 6 species,
all endemic to southern Africa. |
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Subfamily: Sesuvioideae
Sesuvium About 12
species, found in the tropics and subtropics, mainly African with about 4
species in southern Africa. Occurs on saline dunes and beaches, and in
riverbeds and marshes. |
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Trianthema About 17
species, found in the tropics and subtropics worldwide, with 6 species
found in southern Africa. |
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Zaleya Six species, found
in Africa, Asia and Australia, with one species, Zaleya pentandra,
found in southern Africa. |
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Subfamily: Tetragonioideae (sometimes put at family
level as the Tetragoniaceae)
Tetragonia The 50-60
species are found in Asia, Africa, Australia, New Zealand and temperate
South America. About 40 species are found in southern Africa. |
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Tribulocarpus One species:
Tribulocarpus dimorphanthus, endemic to Namibia. |
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The 'Mesems'
Publications
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