TheAPG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostlymolecular-based,system of plant taxonomy that was published in April 2003 by theAngiosperm Phylogeny Group.[1] It was a revision of the firstAPG system, published in 1998, and was superseded in 2009 by a further revision, theAPG III system.
APG II was published as:
Each of the APG systems represents the broad consensus of a number ofsystematicbotanists, united in the APG, working at several institutions worldwide.
The APG II system recognized 45orders, five more than the APG system. The new orders wereAustrobaileyales,Canellales,Gunnerales,Celastrales, andCrossosomatales, all of which were families unplaced as to order, although contained insupra-ordinal clades, in the APG system. APG II recognized 457families, five fewer than the APG system. Thirty-nine of the APG II families were not placed in any order, but 36 of the 39 were placed in a supra-ordinal clade within the angiosperms. Fifty-five of the families came to be known as "bracketed families". They were optionalsegregates of families that could becircumscribed in alarger sense.
The APG II system was influential and was adopted in whole or in part (sometimes with modifications) in a number of references. It was superseded 6½ years later by theAPG III system, published in October 2009.
Main groups in the system (allunrankedclades between theranks ofclass andorder):
Shown below is the classification in full detail, except for the fifteen genera and three families that wereunplaced in APG II. The unplacedtaxa were listed at the end of the appendix in a section entitled "Taxa of Uncertain Position". Under some of the clades are listed the families that were placedincertae sedis in that clade. Thirty-six families were so placed. This means that theirrelationship to other members of the clade is not known.
Note: "+ ..." = optionally separate family, that may be split off from the preceding family.
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