Actinidiaceae
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Actinidiaceae, or the Chinese Gooseberry family, is a small family of plants. It includes three genera and about 360 species. It is a member of the order Ericales.[1]
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[edit] Distribution
They are temperate and subtropical woody vines, shrubs and trees, native to Asia (Actinidia or kiwifruit, Clematoclethra, Saurauia) and Central America and South America (Saurauia only). Saurauia is with its 300 species the largest genus in this family. Although now confined to Asia and tropical Central and South America, there is evidence that in the past the family had a wider distribution. The now extinct genus Parasaurauia is thought to have belonged to the Actinidiaceae and was located in North America during th early Campanian.[2]
[edit] Characterisitics
The plants are usually small trees or shrubs, or sometimes vines (Actinidia). The alternate, simple, spiral leaves have serrate or entire margins. They lack stipules or are minutely stipulate. They are often beset with rather flattened bristles.
The flowers grow solitary or are aggregated in terminal cymes, with free sepals and petals. Except for members of the genus Clematoclethra which have 10 stamens, the stamens are numerous and originally attached at the back.[3] They invert just before the flower starts expanding, so that their bases become apical.
The plants may be monoecious, dioecious or hermaphroditic. The fruit is usually a berry, such as the edible kiwifruit, a cultivar from the genus Actinidia.
[edit] Evidence Supporting Placement within the Ericales
Before genetic evidence appeared in the last 10 years, the placement of the Actinidiaceae within the Ericales was highly controversial. The USDA plants database, a resource that is considered authoratative, still places the Actinidaceae within the Theales, an order which has been shown not to be monophyletic.[4] Placement of the Actinidiaceae within the Ericales has been strongly supported by genetic evidence over the past 10 years, and contrary to previous thought, it is not a basal member of the Ericales. Multiple studies using genetic evidence now firmly place the Actinidiaceae in the Ericoid clade, a monophyletic group consisting of the Ericaceae, the Cyrillaceae, the Clethraceae, the Sarraceniaceae, and the Roridulaceae. Furthermore, genetic evidence points to the Actinidiaceae being sister to the Roridulaceae, and with the Roridulaceae and Sarraceniaceae, forming another, smaller, monophyletic group.[5]
[edit] Evidence Supporting Monophyly of the Actinidiaceae
What genera were to be placed in the Actinidiaceae before recent genetic and micromophological studies emerged was highly controversial. Before recent evidence, the genus Sladenia was often placed within the Actinidiaceae. Also, Saurauia was sometimes considered its own family. Thus, before 10 years ago when more detailed studies started, it was considered that there could be anywhere from 2-4 genera within the Actinidiaceae. Micromorphological characters have confirmed that Sladenia does not belong in the Actinidiaceae. Furthermore, biological characteristics of the cells, and molecular evidence, have confirmed that the 3 genera currently circumscribed in the Actinidiaceae, the Clematoclethra, Saurauia, and Actinidia do indeed form a monophyletic group.[6][7]
[edit] References
- ^ Anderberg et al. "Phylogenetic Relationships in the Order Ericales S.L.: Analyses of Molecular Data from Five Genes from the Plastd and Mitochondrial Genomes" American Journal of Botany 89(4): 677-687. 2002
- ^ Keller et al. "Fossil Flowers and Fruits of the Actinidiaceae from the Campanian (Late Cretaceous) of Georgia" American Journal of Botany Vol. 83, No. 4. (1996) pp. 528-541
- ^ Keller et al. "Fossil Flowers and Fruits of the Actinidiaceae from the Campanian (Late Cretaceous) of Georgia" American Journal of Botany Vol. 83, No. 4. (1996) pp. 528-541
- ^ The Angiosperm Phylogeny Group "An Ordinal Classifcation for the Families of Flowering Plants" Annals of the Missouri Botanical Garden Vol. 85, No. 4. (1998), p. 531-553
- ^ Schoengerger et al. "Molecular Phylogenetics and Patterns of Floral Evolution in the Ericales" International Journal of Plant Sciences Mar 2005; 166, 2; pg. 265
- ^ Li et al. "Molecular Phylogeny and Infrageneric Classification of Actinidia (Actinidiaceae)" Systematic Botany (2002), 27(2): pp. 408-415
- ^ He et al. "The cytology of Actinidia, Saurauia, and Clematoclethra(Actinidiaceae)" Botanical Journal of the Linnean Society 2005, Vol. 147, p. 369-374
[edit] External links
- Actinidiaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants. http://delta-intkey.com
- Theales Order in the USDA Plants Database
