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''Acacia s.l.'' ( or ), known commonly as mimosa, acacia, thorntree or wattle, is a polyphyletic genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae. It was described by the Swedish botanist Carl Linnaeus in 1773 based on the African species ''Acacia nilotica''. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not. All species are pod-bearing, with sap and leaves often bearing large amounts of tannins and condensed tannins that historically found use as pharmaceuticals and preservatives. The genus ''Acacia'' constitutes, in its traditional circumspection, the second largest genus in Fabaceae (''Astralagus'' being the largest), with roughly 1,300 species, about 960 of them native to Australia, with the remainder spread around the tropical to warm-temperate regions of both hemispheres, including Europe, Africa, southern Asia, and the Americas (see List of ''Acacia'' species). The genus was divided into five separate genera under the tribe "Acacieae". The genus ''Racosperma'' represents the majority of the Australian species and a few native to southeast Asia, Réunion, and Pacific Islands. Most of the species outside Australia, and a small number of Australian species, are classified into ''Acacia'' and ''Senegalia''. The two final genera, ''Acaciella'' and ''Mariosousa'', each contain about a dozen species from the Americas (but see "Classification" below for the ongoing debate concerning their taxonomy). This article describes acacias in the broader sense. ==Classification== English botanist and gardener Philip Miller adopted the name ''Acacia'' in 1754. The generic name derives from (), the name given by early Greek botanist-physician Pedanius Dioscorides (middle to late first century) to the medicinal tree ''A. nilotica'' in his book ''Materia Medica''. This name derives from the Ancient Greek word for its characteristic thorns, (; "thorn"). The species name ''nilotica'' was given by Linnaeus from this tree's best-known range along the Nile river. This became the type species of the genus. The traditional circumscription of ''Acacia'' eventually contained approximately 1,300 species. However, evidence began to accumulate that the genus as described was not monophyletic. Queensland botanist Les Pedley proposed the subgenus ''Phyllodineae'' be renamed ''Racosperma'' and published the binomial names. This was taken up in New Zealand but generally not followed in Australia, where botanists declared more study was needed. Eventually, consensus emerged that ''Acacia'' needed to be split as it was not monophyletic. This led to Australian botanists Bruce Maslin and Tony Orchard pushing for the retypification of the genus with an Australian species instead of the original African type species, an exception to traditional rules of priority that required ratification by the International Botanical Congress. That decision has been controversial,〔 and debate continues, with some taxonomists (and many other biologists) deciding to continue to use the traditional ''Acacia sensu lato'' circumscription of the genus,〔 in defiance of decisions by two consecutive International Botanical Congresses. When the genus is divided, the traditional acacias of Africa resort under genera ''Acacia'' and ''Senegalia'', some of the American species are placed in ''Acaciella'' and ''Mariosousa'', and the majority of species in genus ''Racosperma'' are confined to Australia.〔(【引用サイトリンク】url=http://www.anbg.gov.au/acacia/ )〕 In common parlance, the term "acacia" is occasionally applied to species of the genus ''Robinia'', which also belongs in the pea family. ''Robinia pseudoacacia'', an American species locally known as black locust, is sometimes called "false acacia" in cultivation in the United Kingdom and throughout Europe. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Acacia sensu lato」の詳細全文を読む スポンサード リンク
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