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 that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, ...

-based, system of plant taxonomy that was published in April 2003 by the

Angiosperm Phylogeny Group The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disc ...

.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 The ''Botanical Journal of the Linnean Society'' is a scientific journal publishing original papers relating to the taxonomy of all plant groups and fungi, including anatomy, biosystematics, cytology, ecology, ethnobotany, electron microscopy, ...

'' 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, published in 1998, and was superseded in 2009 by a further revision, the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 Published in 2009, it was superseded in 2016 by a f ...

. __TOC__

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". ''

'' 141(4): 399-436. (Available online
Abstract

Full text (HTML)

Full text (PDF)
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 introduced by an inaccuracy inherent to the system Economy * Systematic trading, a way of defining trade goals, risk control ...

botanist Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...

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

orders Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * H ...

, five more than the APG system. The new orders were

Austrobaileyales Austrobaileyales is an order of flowering plants consisting of about 100 species of woody plants growing as trees, shrubs and lianas. A well known example is '' Illicium verum'', commonly known as star anise. The order belongs to the group of b ...

Canellales Canellales is the botanical name for an order of flowering plants, one of the four orders of the magnoliids. It is recognized by the most recent classification of flowering plants, the APG IV system. It is defined to contain two families: Canel ...

, Gunnerales, Celastrales, and

Crossosomatales The Crossosomatales are an order, first recognized as such by APG II. They are flowering plants included within the Rosid eudicots. Description Species assigned to the Crossosomatales have in common flowers that are positioned solitarily, wi ...

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

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

, 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 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

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s between the ranks of

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

and

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

): *angiosperms : *:

magnoliids Magnoliids, Magnoliidae or Magnolianae are a clade of flowering plants. With more than 10,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and many others, it is the third-largest group of angiospe ...

monocots Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are flowering plants whose seeds contain only one embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but with various ranks a ...

*::

commelinids In plant taxonomy, commelinids (originally commelinoids) is a clade of flowering plants within the monocots, distinguished by having cell walls containing ferulic acid. Well-known commelinids include palms and relatives (order Arecales), dayf ...

eudicots The eudicots or eudicotyledons are flowering plants that have two seed leaves (cotyledons) upon germination. The term derives from ''dicotyledon'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors h ...

*::

core eudicots The eudicots or eudicotyledons are flowering plants that have two seed leaves (cotyledons) upon germination. The term derives from ''dicotyledon'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors h ...

*:::

rosids The rosids are members of a large clade (monophyly, monophyletic group) of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms. The clade is divided into 16 to 20 Order (biology), orders, depending upon Circu ...

*:::: eurosids I *:::: eurosids II *:::

asterids Asterids are a large clade (monophyly, monophyletic group) of flowering plants, composed of 17 Order_(biology), orders and more than 80,000 species, about a third of the total flowering plant species. The asterids are divided into the unranked cl ...

*:::: 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. The unplaced

taxa In biology, a taxon (back-formation from ''taxonomy''; : 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 name and ...

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 is a term used for a taxonomy (biology), 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, uncertainty ...

in that clade. Thirty-six families were so placed. This means that their relationship to other members of the clade is not known. *angiosperms : *:

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

grade

basal angiosperms The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal angiosperms were called the ANITA grade, which is made up of ''Amborella'' (a single species of shrub f ...

*::: family Amborellaceae *::: family

Chloranthaceae Chloranthaceae ( ) is a family of flowering plants (angiosperms), the only family in the order Chloranthales. It is not closely related to any other family of flowering plants, and is among the early-diverging lineages in the angiosperms. They a ...

*::: family

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

family Cabombaceae">Cabombaceae.html" ;"title=" family Cabombaceae"> family Cabombaceae*:: order

*:: order Ceratophyllales *: clade

*::: order

Laurales The Laurales are an order of flowering plants. They are magnoliids, related to the Magnoliales. The order includes about 2500–2800 species from 85 to 90 genera, which comprise seven families of trees and shrubs. Most of the species are tropic ...

*::: order

Magnoliales The Magnoliales are an order of flowering plants. Well-known members of Magnoliales include: magnolias, Liriodendron, tulip trees, Annona squamosa, custard apples, Asimina triloba, American pawpaw, cherimoyas, Cananga odorata, ylang-ylang, Sours ...

*::: order

Piperales Piperales is an order of flowering plants (4,170 recognized species). It necessarily includes the family Piperaceae but other taxa have been included or disincluded variously over time. Well-known plants which may be included in this order inclu ...

*: clade

*:::: family

Petrosaviaceae Petrosaviaceae is a family of flowering plants belonging to a monotypic order, Petrosaviales. Petrosaviales are monocots, and are grouped within the lilioid monocots. Petrosaviales is a very small order composed of one family, two genera and fou ...

*::: order

Acorales ''Acorus'' is a genus of monocot flowering plants. This genus was once placed within the family Araceae (aroids), but more recent classifications place it in its own family Acoraceae and order Acorales, of which it is the sole genus of the oldes ...

*::: order

Alismatales The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Perhaps the most important food cro ...

*::: order

Asparagales Asparagales (asparagoid lilies) are a diverse order of flowering plants in the monocots. Under the APG IV system of flowering plant classification, Asparagales are the largest order of monocots with 14 families, 1,122 genera, and about 36,00 ...

*::: order

Dioscoreales The Dioscoreales are an order of monocotyledonous flowering plants, organized under modern classification systems, such as the Angiosperm Phylogeny Group or the Angiosperm Phylogeny Web. Among monocot plants, Dioscoreales are grouped with the ...

*::: order

Liliales Liliales is an order (biology), order of monocotyledonous flowering plants in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web List of systems of plant classification, system, within the lilioid monocots. This order of necessity includ ...

*::: order

Pandanales Pandanales, the pandans or screw-pines, is an order of flowering plants placed in the monocot clade in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web systems. Within the monocots Pandanales are grouped in the lilioid monocots where ...

*::clade

*::::: family

Dasypogonaceae Dasypogonaceae is a family of flowering plants based on the type genus '' Dasypogon'', one that has traditionally not been commonly recognized by taxonomists; the plants it contains were usually included in the family Xanthorrhoeaceae. If valid ...

*:::: order

Arecales Arecales is an order of flowering plants. The order has been widely named as such only for the past few decades; until then, the accepted name for the order including these plants was Principes. The order includes palms and relatives. Taxonomy ...

*:::: order

Commelinales Commelinales is an order of flowering plants. It comprises five families: Commelinaceae, Haemodoraceae, Hanguanaceae, Philydraceae, and Pontederiaceae. All the families combined contain over 885 species in about 70 genera; the majority of s ...

*:::: order

Poales The Poales are a large order (biology), order of flowering plants in the monocotyledons, and includes families of plants such as the Poaceae, grasses, bromeliads, Juncaceae, rushes and Cyperaceae, sedges. 14 plant families are currently recogniz ...

*:::: 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 morpholog ...

*: clade

*:::: family

Buxaceae The Buxaceae are a small family of six genera and about 123 known species of flowering plants. They are shrubs and small trees, with a cosmopolitan distribution. A seventh genus, sometimes accepted in the past (''Notobuxus''), has been shown by ...

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

*::::: family Aextoxicaceae *::::: family Berberidopsidaceae *::::: family

Dilleniaceae Dilleniaceae is a family of flowering plants with 11 genera and about 430 known species. It is known to gardeners for the genus '' Hibbertia'', which contains many commercially valuable garden species. Description and distribution The family is ...

*:::: order Gunnerales *:::: order

Caryophyllales Caryophyllales ( ) is a diverse and heterogeneous order of flowering plants with well-known members including cacti, carnations, beets, quinoa, spinach, amaranths, pigfaces and ice plants, oraches and saltbushes, goosefoots, sundews, Venu ...

*:::: order

Santalales The Santalales are an order (biology), order of flowering plants in the dicotyledons. Well-known members of the Santalales include Santalum, sandalwoods and the many species of mistletoes. The order has a cosmopolitan distribution, but is heavily ...

*:::: order

Saxifragales Saxifragales is an order (biology), order of flowering plants in the Superrosids, superrosid clade of the eudicots. It contains 15 Families (biology), families and around 100 genera, with nearly 2,500 species. Well-known and economically import ...

*::: clade

*:::::: family

Aphloiaceae ''Aphloia'' is a genus of flowering plants that contains a single species, ''Aphloia theiformis'', the sole species of the monogeneric family Aphloiaceae. It is a species of evergreen shrubs or small trees occurring in East Africa, Madagasca ...

*:::::: 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 ...

*:::::: family Picramniaceae *:::::: family

Strasburgeriaceae Strasburgeriaceae is a small family of flowering plants in the order Crossosomatales, only found in New Zealand and New Caledonia. It contains two Genus, genera, ''Strasburgeria'' and ''Ixerba''. Both genera have simple, evergreen, alternated lea ...

*:::::: family

Vitaceae The Vitaceae are a family of flowering plants, with 14 genera and around 910 known species, including common plants such as Vitis, grapevines (''Vitis'' spp.) and Parthenocissus quinquefolia, Virginia creeper (''Parthenocissus quinquefolia''). Th ...

*::::: order

Geraniales Geraniales is a small order (biology), order of flowering plants, included within the rosid subclade of eudicots. The largest family (biology), family in the order is Geraniaceae with over 800 species. In addition, the order includes the smaller ...

*::::: order Myrtales *:::: clade eurosids I *::::::: family

Zygophyllaceae Zygophyllaceae is a family of flowering plants that contains the bean-caper and caltrop. The family includes around 285 species in 22 genera. Plants in the family Zygophyllaceae may be trees, shrubs, or herbs. They are often found in dry habit ...

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 Order (biology), orders of flowering plants. The order is very diverse, with well-known members including willows, Viola (plant), violets, aspens and Populus, poplars, Euphorbia pulcherrima, poinsett ...

*:::::: order Oxalidales *:::::: order

Rosales Rosales (, ) are an order of flowering plants. Peter F. Stevens (2001 onwards). "Rosales". At: Trees At: Angiosperm Phylogeny Website. At: Missouri Botanical Garden Website. (see ''External links'' below) Well-known members of Rosales include: ...

*:::: clade eurosids II *::::::: family Tapisciaceae *:::::: order

Brassicales The Brassicales (or Cruciales) are an order (biology), order of flowering plants, belonging to the malvid group of eudicotyledons under the APG IV system. Well-known members of Brassicales include cabbage, cauliflower, Brussels sprout, broccoli, ...

*:::::: order

Malvales The Malvales are an Order (biology), order of flowering plants. As circumscribed by Angiosperm Phylogeny Group, APG II-system, the order includes about 6000 species within nine Family (biology), families. The order is placed in the eurosids II, w ...

*:::::: order

Sapindales Sapindales is an order of flowering plants. Well-known members of Sapindales include citrus; maples, horse-chestnuts, lychees and rambutans; mangos and cashews; frankincense and myrrh; mahogany and neem. The APG III system of 2009 includ ...

*::: clade

*::::: order Cornales *::::: order

Ericales The Ericales are a large and diverse order of flowering plants in the asterid group of the eudicots. Well-known and economically important members of this order include tea and ornamental camellias, persimmon, ebony, blueberry, cranberry, l ...

*:::: clade euasterids I *::::::: family

Boraginaceae Boraginaceae, the Borago, borage or forget-me-not family, includes about 2,000 species of shrubs, trees, and herbs in 146 to 154 genus, genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single famil ...

*::::::: family

Icacinaceae The Icacinaceae, also called the white pear family, are a family (biology), family of flowering plants,"Icacinaceae" At: Angiosperm Phylogeny Website At: Missouri Botanical Garden Website (see ''External links'' below). consisting of trees, shrub ...

*::::::: family Oncothecaceae *::::::: family

Vahliaceae ''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 family had previously been placed in the order Saxifragales, an ...

*:::::: order Garryales *:::::: order

Gentianales Gentianales is an order of flowering plant, included within the asterid clade of eudicots. It comprises more than 20,000 species in about 1,200 genera in 5 families. More than 80% of the species in this order belong to the family Rubiaceae. Man ...

*:::::: order

Lamiales The Lamiales (also known as the mint order) are an order of flowering plants in the asterids clade of the Eudicots. Under the APG IV system of flowering plant classification the order consists of 24 families, and includes about 23,810 species ...

*:::::: order

Solanales The Solanales are an order of flowering plants, included in the asterid group of the eudicots. Well-known members of Solanales include potatoes, eggplants, tomatoes, chili peppers, tobacco, petunias, nightshades, morning glory, and sweet potato. ...

*:::: 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 The Aquifoliales are an order of flowering plants, including the Aquifoliaceae (holly) family, and also the Helwingiaceae (2-5 species of temperate Asian shrubs) and the Phyllonomaceae (4 species of Central American trees and shrubs). In 2001, ...

*:::::: order

Asterales Asterales ( ) is an Order (biology), order of dicotyledonous flowering plants that includes the large Family (biology), family Asteraceae (or Compositae) known for composite flowers made of Floret#floret, florets, and ten families related to th ...

*:::::: order

Dipsacales The Dipsacales are an order of flowering plants, included within the asterid group of dicotyledons. In the APG III system of 2009, the order includes only two families, Adoxaceae and a broadly defined Caprifoliaceae. Some well-known members of ...

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