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APG IV system

Evolution of angiosperms shown in diagram format, per APG IV

The APG IV system of flowering plant classification is the fourth version of a modern, mostly molecular-based, system of plant taxonomy for flowering plants (angiosperms) being developed by the Angiosperm Phylogeny Group (APG). It was published in 2016, seven years after its predecessor the APG III system was published in 2009, and 18 years after the first APG system was published in 1998.[1] In 2009, a linear arrangement of the system was published separately;[2] the APG IV paper includes such an arrangement, cross-referenced to the 2009 one.[1]

Compared to the APG III system, the APG IV system recognizes five new orders (Boraginales, Dilleniales, Icacinales, Metteniusales and Vahliales), along with some new families, making a total of 64 angiosperm orders and 416 families.[1] In general, the authors describe their philosophy as "conservative", based on making changes from APG III only where "a well-supported need" has been demonstrated. This has sometimes resulted in placements that are not compatible with published studies, but where further research is needed before the classification can be changed.[3]

Short version

Detailed version

Key to symbols used:

* = the family has been added or its circumscription changed since the APG III system of 2009
† = the order has been added since the APG III system

Independent lineage: unplaced to more inclusive clade

Probable sister of eudicots

Fabids

COM clade; placement uncertain
Malvids
Lamiids
Campanulids

Phylogeny

Like the earlier APG systems, the APG IV revision is based on a phylogenetic tree for the angiosperms, as shown below.[4]

References

Bibliography