Family: Fabaceae |
THIS DESCRIPTION IS FOR ACACIA in the narrow sense, i.e., excluding Vachellia, Senegalia, Faidherbia and other segregates Plants shrubs or trees. Leaves bipinnate or modified to polymorphic phyllodes, sometimes partly concurrent with branchlets, sometimes appearing simple, rarely reduced to scales or absent; stipules usually present and scarious but commonly caducous, rarely spinose; foliar glands normally present. Inflorescences pedunculate or sessile, usually simple or racemose, infrequently paniculate; bracteoles usually present; flowers white to golden, rarely mauve-pink or red , 2 or more aggregated into globular heads or obloid to cylindrical spikes, (3–) 4 or 5 (–6)-merous; sepals usually free or united, rarely absent; stamens numerous, usually free, rarely united basally into a short tube or irregularly faciculate; ovaries usually single, rarely to 5, usually sessile, rarely stipitate. Legumes dehiscent or rarely indehiscent; seeds usually with a pleurogram and without endosperm; funicles arillate or exarillate. Acacia sens. str. is largely confined to Australia with 1063 of the 1067 total number of species being mostly endemic and occurring throughout mainland Australia, Tasmania and nearby islands; c. 20 taxa occur naturally outside Australia, mostly in southeast Asia (north to Taiwan) and islands of the Pacific (east to Hawaii); 7 of the Asia–Pacific species also occur in Australia; 1 species, A. heterophylla (= A. koa) occurs in the Mascarene Islands (Indian Ocean). Acacia species are widely cultivated, including overseas plantations, for timber, tannin, oils, ornamental horticulture and increasingly bush tucker and cut flowers. Many taxa have become naturalised, including several species considered noxious weeds in parts of Australia and overseas. Acacia sensu lato and Acacia sensu stricto Interpretation of what should be included in Acacia changed a lot around 2000. By then there was considerable evident that the traditional interpretation of the genus included many distantly related lineages (or, in today's terminology, it was polyphyletic). If genera are to be monophyletic, then Acacia has to be split into several different genera. In 2003, it was decided that, if the genus is split, the name Acacia should be retained for a group of Australian species and all other species placed in other genera. There is growing acceptance that recognizing multiple genera within what used to be treated as Acacia (Acacia s.l.) is the most appropriate treatment. That is the treatment adopted on this web site. The genera that grow in Africa and southwest Asia are (in alphabetical order) Acacia s.s. (introduced), Faidherbia, Senegalia, and Vachellia. Most printed floristic works use Acacia s.l. This usage is also embedded in many ecological descriptions, for example, references to Acacia - Commiphora woodlands. Plants shrubs or trees. Leaves bipinnate or modified to polymorphic phyllodes, sometimes resulting in what seem like simple leaves; phyllodes sometimes partly concurrent with branchlets, rarely reduced to scales or absent; stipules usually present and scarious but often caducous, rarely spinose. (e.g. spinescent stipules in A. paradoxa, A. victoriae); foliar glands usually present. Inflorescences pedunculate or sessile, simple or racemose, infrequently paniculate; bracteoles normally present; flowers white to golden, rarely mauve-pink (A. purpureopetala) or red (A. leprosa 'Scarlet Blaze'), 2 or more aggregated into globular heads or obloid to cylindrical spikes, (3–) 4 or 5 (–6)-merous; sepals free to united, rarely absent; stamens numerous, usually free, rarely united basally into a short tube or irregularly faciculate; ovaries single (rarely to 5), usually sessile, rarely stipitate. Legumes usually dehiscent, rarely indehiscent; seeds usually with a pleurogram and without endosperm; funicle arillate or exarillate. Acacia sens. str. is largely confined to Australia with 1063 of the 1067 total number of species being endemic to tAustralia and nearby islands; c. 20 taxa occur naturally outside Australia, mostly in southeast Asia (north to Taiwan) and islands of the Pacific (east to Hawaii); 7 of the Asia–Pacific species also occur in Australia; 1 species, A. heterophylla (= A. koa) occurs in the Mascarene Islands (Indian Ocean).
Acacia species are widely cultivated, including overseas plantations, for timber, tannin, oils, ornamental horticulture and increasingly bush tucker and cut flowers. Many taxa have become naturalised, including several species considered noxious weeds in parts of Australia and overseas. Global distribution of Acacia sensu stricto. This map undoubtedly includes many records of introduced and cultivated plants that were not labelled as such. |