APG system

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The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly molecular-based, system of plant taxonomy. Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved APG II in 2003, APG III system in 2009 and APG IV system in 2016.

History[]

The original APG system is unusual in being based, not on total evidence, but on the cladistic analysis of the DNA sequences of three genes, two chloroplast genes and one gene coding for ribosomes. Although based on molecular evidence only, its constituent groups prove to be supported by other evidence as well, for example pollen morphology supports the split between the eudicots and the rest of the former dicotyledons.

The system is rather controversial in its decisions at the family level, splitting a number of long-established families and submerging some other families. It also is unusual in not using botanical names above the level of order, that is, an order is the highest rank that will have a formal botanical name in this system. Higher groups are defined only as clades, with names such as monocots, eudicots, rosids, asterids.

The APG system was superseded in 2003 by a revision, the APG II system, in 2009 by a next revision, the APG III system, and then in 2016 by a further revision, the APG IV system.

Groups[]

The main groups in the system (all unranked clades) are:

  • angiosperms :
    monocots
    commelinoids
    eudicots
    core eudicots
    rosids
    eurosids I
    eurosids II
    asterids
    euasterids I
    euasterids II

Representation in color

The APG system recognises 462 families and 40 orders: these are assigned as follows. In the beginning of each listing some families or orders that are not placed in a further clade:

Note: "+ ..." = optional seggregrate family, that may be split off from the preceding family.

  • Families of uncertain position
    family Balanophoraceae
    family Bonnetiaceae
    family Cardiopteridaceae
    family Ctenolophonaceae
    family Cynomoriaceae
    family Cytinaceae
    family Dipentodontaceae
    family Elatinaceae
    family Geissolomataceae
    family Hoplestigmataceae
    family Kaliphoraceae
    family Lepidobotryaceae
    family
    family Lophopyxidaceae
    family Medusandraceae
    family Metteniusaceae
    family Mitrastemonaceae
    family Paracryphiaceae
    family Pentaphylacaceae
    family Peridiscaceae
    family
    family
    family Sladeniaceae
    family Strasburgeriaceae
    family

See also[]

References[]

  • The Angiosperm Phylogeny Group (1998). "An ordinal classification for the families of flowering plants". Annals of the Missouri Botanical Garden. 85 (4): 531–553. doi:10.2307/2992015. JSTOR 2992015. (Available online: (PDF))

External links[]

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