The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Group.Angiosperm Phylogeny Group (2003)
An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II.
'' Botanical Journal of the Linnean Society'' 141(4): 399-436. doi: 10.1046/j.1095-8339.2003.t01-1-00158.x It was a revision of the first

APG system 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 ...

, published in 1998, and was superseded in 2009 by a further revision, the

APG III system The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a fu ...

History

APG II was published as: *Angiosperm Phylogeny Group (2003). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II". '' Botanical Journal of the Linnean Society'' 141(4): 399-436. (Available online
Abstract

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doi: 10.1046/j.1095-8339.2003.t01-1-00158.x) Each of the APG systems represents the broad consensus of a number of

systematic Systematic may refer to: Science * Short for systematic error * Systematic fault * Systematic bias, errors that are not determined by chance but are introduced by an inaccuracy (involving either the observation or measurement process) inheren ...

botanists, united in the APG, working at several institutions worldwide. The APG II system recognized 45

orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

, five more than the APG system. The new orders were Austrobaileyales, Canellales, Gunnerales, Celastrales, and

Crossosomatales The Crossosomatales are an order, first recognized as such by Angiosperm Phylogeny Group, APG II. They are flowering plants included within the Rosids, Rosid eudicots. Description Species assigned to the Crossosomatales have in common flowers ...

, all of which were families unplaced as to order, although contained in supra-ordinal clades, in the APG system. APG II recognized 457 families, 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 optional segregates of families that could be

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every po ...

in a larger 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 the

, published in October 2009.

Groups

Main groups in the system (all unranked clades between the ranks of class and

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

): *angiosperms : *: magnoliids *: monocots *:: commelinids *: eudicots *:: core eudicots *::: rosids *:::: eurosids I *:::: eurosids II *::: asterids *:::: euasterids I *:::: euasterids II Shown below is the classification in full detail, except for the fifteen genera and three families that were

unplaced in APG II When the APG II system of plant classification was published in April 2003, fifteen genera and three families were placed incertae sedis in the angiosperms, and were listed in a section of the appendix entitled "Taxa of uncertain position". By ...

. The unplaced

taxa In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

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 placed

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

in that clade. Thirty-six families were so placed. This means that their

relationship Relationship most often refers to: * Family relations and relatives: consanguinity * Interpersonal relationship, a strong, deep, or close association or acquaintance between two or more people * Correlation and dependence, relationships in mathem ...

to other members of the clade is not known. *

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

grade basal angiosperms *::: family Amborellaceae *::: family Chloranthaceae *::: family

Nymphaeaceae Nymphaeaceae () is a family of flowering plants, commonly called water lilies. They live as rhizomatous aquatic herbs in temperate and tropical climates around the world. The family contains nine genera with about 70 known species. Water ...

family Cabombaceae">Cabombaceae.html" ;"title=" family Cabombaceae"> family Cabombaceae*:: order Austrobaileyales *:: order Ceratophyllales *: clade magnoliids *::: order Canellales *::: order Laurales *::: order Magnoliales *::: order Piperales *: clade monocots *:::: family Petrosaviaceae *::: order Acorales *::: order Alismatales *::: order Asparagales *::: order Dioscoreales *::: order Liliales *::: order Pandanales *::clade commelinids *::::: family Dasypogonaceae *:::: order

Arecales Arecales is an order of flowering plants. The order has been widely recognised only for the past few decades; until then, the accepted name for the order including these plants was Principes. Taxonomy The APG IV system of 2016 places Dasypog ...

*:::: order Commelinales *:::: order Poales *:::: order

Zingiberales The Zingiberales are flowering plants forming one of four orders in the commelinids clade of monocots, together with its sister order, Commelinales. The order includes 68 genera and 2,600 species. Zingiberales are a unique though morphol ...

*: clade eudicots *:::: family Buxaceae family Didymelaceae">Didymelaceae.html" ;"title=" family Didymelaceae"> family Didymelaceae*:::: family Sabiaceae *:::: family Trochodendraceae [+ family Tetracentraceae] *::: order Proteales *::: order Ranunculales *:: clade core eudicots *::::: family

Aextoxicaceae ''Aextoxicon punctatum'', the sole species of genus ''Aextoxicon'' and family Aextoxicaceae, is a dioecious tree native to southern Chile and Argentina. Commonly known as the ''olivillo'' or ''aceitunillo'', it is a large evergreen tree native to ...

*::::: family

Berberidopsidaceae Berberidopsidaceae is a family of flowering plants. Such a family has only recently been recognized by more than a few taxonomists: the plants involved have often been treated as belonging to family Flacourtiaceae. The APG II system, of 2003 (un ...

*::::: family Dilleniaceae *:::: order Gunnerales *:::: order Caryophyllales *:::: order Santalales *:::: order Saxifragales *::: clade rosids *:::::: family Aphloiaceae *:::::: family Geissolomataceae *:::::: family

Ixerbaceae ''Ixerba brexioides'', the sole species in the genus ''Ixerba'', is a bushy tree with thick, narrow, serrated, dark green leaves and panicles of white flowers with a green heart. The fruit is a green capsule that splits open to reveal the black s ...

*:::::: family Picramniaceae *:::::: family Strasburgeriaceae *:::::: family Vitaceae *::::: order

*::::: order Geraniales *::::: order

Myrtales The Myrtales are an order of flowering plants placed as a sister to the eurosids II clade as of the publishing of the ''Eucalyptus grandis'' genome in June 2014. The APG III system of classification for angiosperms still places it within the eur ...

*:::: clade eurosids I *::::::: family Zygophyllaceae family Krameriaceae">Krameriaceae.html" ;"title=" family Krameriaceae"> family Krameriaceae*::::::: family Huaceae *:::::: order Celastrales *:::::: order Cucurbitales *:::::: order Fabales *:::::: order Fagales *:::::: order

Malpighiales The Malpighiales comprise one of the largest orders of flowering plants, containing about 36 families and more than species, about 7.8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, poinse ...

*:::::: order Oxalidales *:::::: order Rosales *:::: clade eurosids II *::::::: family Tapisciaceae *:::::: order Brassicales *:::::: order Malvales *:::::: order Sapindales *::: clade asterids *::::: order Cornales *::::: order Ericales *:::: clade euasterids I *::::::: family Boraginaceae *::::::: family Icacinaceae *::::::: family Oncothecaceae *::::::: family

Vahliaceae :''The later homonym Vahlia Dahl is now known as Dombeya.'' ''Vahlia'' is a genus of herbs and subshrubs that grow in Africa and the Indian subcontinent. There are at least five species. The genus is placed alone in family ''Vahliaceae''. This ...

*:::::: order Garryales *:::::: order Gentianales *:::::: order Lamiales *:::::: order Solanales *:::: clade euasterids II *::::::: family Bruniaceae *::::::: family Columelliaceae family Desfontainiaceae">Desfontainiaceae.html" ;"title=" family Desfontainiaceae"> family Desfontainiaceae*::::::: family Eremosynaceae *::::::: family Escalloniaceae *::::::: family Paracryphiaceae *::::::: family Polyosmaceae *::::::: family Sphenostemonaceae *::::::: family Tribelaceae *:::::: order Apiales *:::::: order Aquifoliales *:::::: order Asterales *:::::: order Dipsacales Note: "+ ..." = optionally separate family, that may be split off from the preceding family.

References

{{List of systems of plant taxonomy APG 02 * 2003 in science 2003 introductions Angiosperm Phylogeny Group