APG system

From Wikipedia, the free encyclopedia
Jump to: navigation, search

The APG system (Angiosperm Phylogeny Group system) of plant classification is the first, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in 1998 by the Angiosperm Phylogeny Group. It was superseded in 2003 by a revision, the APG II system, and then in 2009 by a further revision, the APG III system. 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 a number of 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 main groups in the system (all unranked clades) are:

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.

See also[edit]

References[edit]

  • 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[edit]