|
Family: Aizoaceae (vygie,
mesem family)
[= Mesembryanthemaceae]
Life
> eukaryotes >
Archaeoplastida >
Chloroplastida
>
Charophyta > Streptophytina > Plantae (land plants)
> Tracheophyta (vascular plants) > Euphyllophyta > Lignophyta (woody plants)
> Spermatophyta (seed plants) > Angiospermae (flowering
plants)
> Eudicotyledons > Core Eudicots > Order: Caryophyllales
Worldwide there are about 1854 species in 135 genera in
the family Aizoaceae, and most of these species are native to southern Africa
(1735 species in 134 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 the Aizoaceae 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 to southern Africa
Subfamily: Aizooideae
Acrosanthes
Five species, endemic to the Western Cape. |
|
Aizoanthemum
Four
species, endemic to Namibia. |
|
Aizoon About 25
species worldwide (mainly in the Mediterranean region), with 11 species
native to southern Africa. |
|
Galenia
Twenty-nine
species, all endemic to southern Africa. |
|
Plinthus
Five species,
all endemic to southern Africa. |
|
Subfamily: Sesuvioideae
Sesuvium About 12 species,
native to the tropics and subtropics, mainly African with five species
native to southern Africa.
Occurs on saline dunes and beaches, and in riverbeds and marshes. |
|
Trianthema About 17
species, found in the tropics and subtropics worldwide, with five species
native to southern Africa. |
|
Zaleya Six species,
native to Africa, Asia and Australia, with one species, Zaleya pentandra,
native to southern Africa. See
Flora of Zimbabwe. |
|
Subfamily: Tetragonioideae (sometimes put at family
level as the Tetragoniaceae)
Tetragonia
The 50-60 species are native to Asia, Africa,
Australia, New Zealand and temperate South America. Thirty-five species
are native to southern Africa. |
|
Tribulocarpus One species:
Tribulocarpus dimorphanthus, endemic to Namibia. |
|
The 'Mesems'
Publications
-
Angiosperm Phylogeny Group 1998. An ordinal
classification for the families of flowering plants. Annals of the
Missouri Botanical Garden 85: 531-553.
-
Klak, C., Reeves, G. and Hedderson, T. 2004. Unmatched tempo
of evolution in southern African semi-desert ice plants. Nature 427,
63–65.
-
Ellis A.G. and Weis A.E. 2006. Coexistence and
differentiation of ‘flowering stones’: the role of local adaptation to soil
microenvironment. J. Ecol. 94, 322–335.
|
