Editing Mimosoideae (section)

=== Relationships ===
In [[George Bentham|Bentham]]'s 1842 [[Circumscription (taxonomy)|circumscription]] of the subfamily Mimosoideae, Acacieae was one of its three constituent tribes, the others being [[Ingeae]] Benth. & Hook.f. and [[Mimoseae]] Bornn.<ref name=shin>{{cite journal|last1=Shinwari|first1=Zabta K. |last2=Jamil |first2=Khansa |last3=Zahra |first3=Nadia Batool |title=Molecular systematics of selected genera of subfamily Mimosoideae-Fabaceae |journal=Pak. J. Bot. |date=2014 |volume=46 |issue=2 |pages=591–598 |url=http://www.pakbs.org/pjbot/PDFs/46(2)/27.pdf |access-date=23 November 2015}}</ref> His Acacieae tribe of 1842 included many genera that were subsequently assigned to tribe Ingeae Benth. In 1875, however, Bentham narrowed his definition of Acacieae so as to include only ''[[Acacia sensu lato|Acacia]]'' Mill.<ref name=millerjt>{{cite journal |last1=Miller |first1=Joseph T. |last2=Bayer|first2=Randall J. |title=Molecular phylogenetics of Acacia (Fabaceae: Mimosoideae) based on the chloroplast MATK coding sequence and flanking TRNK intron spacer regions |journal=Am. J. Bot. |date=April 2001 |volume=88 |issue=4 |pages=697–705 |doi=10.2307/2657071|pmid=11302857 |jstor=2657071 }}</ref>

The only morphological character of Acacieae used to distinguish it from the Ingeae is the presence of free stamens (as in tribe Mimoseae).<ref name=shin/> In the Ingeae they are fused in the form of a tube, whereas in the Acacieae only a few species have the stamens fused at the base. Several characters of the foliage, seeds, seed pods, pollen, and stipules are shared by the two tribes.<ref name=shin/> The flower morphology of ''Acacia s.l.'' has characteristics in common with the genera ''[[Leucaena]]'', ''[[Piptadenia]]'', and ''[[Mimosa]]'' (tribe Mimoseae) and ''[[Enterolobium]]'' and ''[[Lysiloma]]'' (tribe Ingeae).<ref name=rico>{{cite journal |last1=Rico Arce |first1=M. de L. |last2=Bachman |first2=S. |title=A taxonomic revision of ''Acaciella'' (Leguminosae, Mimosoideae) |journal=Anales del Jardín Botánico de Madrid |date=2006-12-30 |volume=63 |issue=2 |pages=189–244 |doi=10.3989/ajbm.2006.v63.i2.7 |doi-access=free }}</ref>

The tribal position of monotypic genus ''[[Faidherbia]]'' <small>A. Chevalier</small> is equivocal.<ref name=lew/> It was included in the Acacieae by Vassal (1981) and Maslin et al. (2003), but Lewis & Rico Arce placed it in tribe Ingeae following Polhill (1994) and Luckow et al. (2003).<ref name=lew/><ref name=tt2>{{cite web|title=Taxon: Genus Faidherbia A. Chevalier, 1934 (plant) |url=http://taxonomicon.taxonomy.nl/TaxonTree.aspx?id=100685 |website=The Taxonomicon |access-date=19 November 2015}}</ref> In the latter case, tribe Acacieae may conform to genus ''[[Acacia sensu lato|Acacia s.l.]]'', pending the latter's relationship to other mimosoid genera. ''Faidherbia'' is troublesome as its stamens are shortly united at their base and its pollen is similar to some taxa in the Ingeae.<ref name=millerjt/>