# 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 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The APG system was superseded in 2003 by a revision, the APG II system, in 2009 by a next revision, the APG III system, and then in 2016 by a further revision, the APG IV system.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
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:
* clade angiosperms
          family Amborellaceae
          family Austrobaileyaceae
          family Canellaceae
          family Chloranthaceae
          family Hydnoraceae
          family Illiciaceae
          family Nymphaeaceae [+ family Cabombaceae]
          family Rafflesiaceae
          family Schisandraceae
          family Trimeniaceae
          family Winteraceae
       order Ceratophyllales
             family Ceratophyllaceae
       order Laurales
             family Atherospermataceae
             family Calycanthaceae
             family Gomortegaceae
             family Hernandiaceae
             family Lauraceae
             family Monimiaceae
             family Siparunaceae
       order Magnoliales
             family Annonaceae
             family Degeneriaceae
             family Eupomatiaceae
             family Himantandraceae
             family Magnoliaceae
             family Myristicaceae
       order Piperales
             family Aristolochiaceae
             family Lactoridaceae
             family Piperaceae
             family Saururaceae
    clade monocots
             family Corsiaceae
             family Japonoliriaceae
             family Nartheciaceae
             family Petrosaviaceae
             family Triuridaceae
          order Acorales
                family Acoraceae
          order Alismatales
                family Alismataceae
                family Aponogetonaceae
                family Araceae
                family Butomaceae
                family Cymodoceaceae
                family Hydrocharitaceae
                family Juncaginaceae
                family Limnocharitaceae
                family Posidoniaceae
                family Potamogetonaceae
                family Ruppiaceae
                family Scheuchzeriaceae
                family Tofieldiaceae
                family Zosteraceae
          order Asparagales
                family Agapanthaceae
                family Agavaceae
                family Alliaceae
                family Amaryllidaceae
                family Anemarrhenaceae
                family Anthericaceae
                family Aphyllanthaceae
                family Asparagaceae
                family Asphodelaceae
                family Asteliaceae
                family Behniaceae
                family Blandfordiaceae
                family Boryaceae
                family Convallariaceae
                family Doryanthaceae
                family Hemerocallidaceae
                family Herreriaceae
                family Hesperocallidaceae
                family Hyacinthaceae
                family Hypoxidaceae
                family Iridaceae
                family Ixioliriaceae
                family Lanariaceae
                family Laxmanniaceae
                family Orchidaceae
                family Tecophilaeaceae
                family Themidaceae
                family Xanthorrhoeaceae
                family Xeronemataceae
          order Dioscoreales
                family Burmanniaceae
                family Dioscoreaceae
                family Taccaceae
                family Thismiaceae
                family Trichopodaceae
          order Liliales
                family Alstroemeriaceae
                family Campynemataceae
                family Colchicaceae
                family Liliaceae
                family Luzuriagaceae
                family Melanthiaceae
                family Philesiaceae
                family Ripogonaceae
                family Smilacaceae
          order Pandanales
                family Cyclanthaceae
                family Pandanaceae
                family Stemonaceae
                family Velloziaceae
       clade commelinoids
                family Abolbodaceae
                family Bromeliaceae
                family Dasypogonaceae
                family Hanguanaceae
                family Mayacaceae
                family Rapateaceae
             order Arecales
                   family Arecaceae
             order Commelinales
                   family Commelinaceae
                   family Haemodoraceae
                   family Philydraceae
                   family Pontederiaceae
             order Poales
                   family Anarthriaceae
                   family Centrolepidaceae
                   family Cyperaceae
                   family Ecdeiocoleaceae
                   family Eriocaulaceae
                   family Flagellariaceae
                   family Hydatellaceae
                   family Joinvilleaceae
                   family Juncaceae
                   family Poaceae
                   family Prioniaceae
                   family Restionaceae
                   family Sparganiaceae
                   family Thurniaceae
                   family Typhaceae
                   family Xyridaceae
             order Zingiberales
                   family Cannaceae
                   family Costaceae
                   family Heliconiaceae
                   family Lowiaceae
                   family Marantaceae
                   family Musaceae
                   family Strelitziaceae
                   family Zingiberaceae
    clade eudicots
             family Buxaceae
             family Didymelaceae
             family Sabiaceae
             family Trochodendraceae [+ family Tetracentraceae]
          order Proteales
                family Nelumbonaceae
                family Platanaceae
                family Proteaceae
          order Ranunculales
                family Berberidaceae
                family Circaeasteraceae [+ family Kingdoniaceae]
                family Eupteleaceae
                family Lardizabalaceae
                family Menispermaceae
                family Papaveraceae [+ family Fumariaceae and family Pteridophyllaceae]
                family Ranunculaceae
       clade core eudicots
                family Aextoxicaceae
                family Berberidopsidaceae
                family Dilleniaceae
                family Gunneraceae
                family Myrothamnaceae
                family Vitaceae
             order Caryophyllales
                   family Achatocarpaceae
                   family Aizoaceae
                   family Amaranthaceae
                   family Ancistrocladaceae
                   family Asteropeiaceae
                   family Basellaceae
                   family Cactaceae
                   family Caryophyllaceae
                   family Didiereaceae
                   family Dioncophyllaceae
                   family Droseraceae
                   family Drosophyllaceae
                   family Frankeniaceae
                   family Molluginaceae
                   family Nepenthaceae
                   family Nyctaginaceae
                   family Physenaceae
                   family Phytolaccaceae
                   family Plumbaginaceae
                   family Polygonaceae
                   family Portulacaceae
                   family Rhabdodendraceae
                   family Sarcobataceae
                   family Simmondsiaceae
                   family Stegnospermataceae
                   family Tamaricaceae
             order Santalales
                   family Olacaceae
                   family Opiliaceae
                   family Loranthaceae
                   family Misodendraceae
                   family Santalaceae
             order Saxifragales
                   family Altingiaceae
                   family Cercidiphyllaceae
                   family Crassulaceae
                   family Daphniphyllaceae
                   family Grossulariaceae
                   family Haloragaceae
                   family Hamamelidaceae
                   family Iteaceae
                   family Paeoniaceae
                   family Penthoraceae
                   family Pterostemonaceae
                   family Saxifragaceae
                   family Tetracarpaeaceae
          clade rosids
                   family Aphloiaceae
                   family Crossosomataceae
                   family Ixerbaceae
                   family Krameriaceae
                   family Picramniaceae
                   family Podostemaceae
                   family Stachyuraceae
                   family Staphyleaceae
                   family Tristichaceae
                   family Zygophyllaceae
                order Geraniales
                      family Francoaceae
                      family Geraniaceae [+ family Hypseocharitaceae]
                      family Greyiaceae
                      family Ledocarpaceae
                      family Melianthaceae
                      family Vivianiaceae
             clade eurosids I
                      family Celastraceae
                      family Huaceae
                      family Parnassiaceae [+ family Lepuropetalaceae]
                      family Stackhousiaceae
                   order Cucurbitales
                         family Anisophylleaceae
                         family Begoniaceae
                         family Coriariaceae
                         family Corynocarpaceae
                         family Cucurbitaceae
                         family Datiscaceae
                         family Tetramelaceae
                   order Fabales
                         family Fabaceae
                         family Polygalaceae
                         family Quillajaceae
                         family Surianaceae
                   order Fagales
                         family Betulaceae
                         family Casuarinaceae
                         family Fagaceae
                         family Juglandaceae
                         family Myricaceae
                         family Nothofagaceae
                         family Rhoipteleaceae
                         family Ticodendraceae
                   order Malpighiales
                         family Achariaceae
                         family Balanopaceae
                         family Caryocaraceae
                         family Chrysobalanaceae
                         family Clusiaceae
                         family Dichapetalaceae
                         family Erythroxylaceae
                         family Euphorbiaceae
                         family Euphroniaceae
                         family Flacourtiaceae
                         family Goupiaceae
                         family Hugoniaceae
                         family Humiriaceae
                         family Irvingiaceae
                         family Ixonanthaceae
                         family Lacistemaceae
                         family Linaceae
                         family Malesherbiaceae
                         family Malpighiaceae
                         family Medusagynaceae
                         family Ochnaceae
                         family Pandaceae
                         family Passifloraceae
                         family Putranjivaceae
                         family Quiinaceae
                         family Rhizophoraceae
                         family Salicaceae
                         family Scyphostegiaceae
                         family Trigoniaceae
                         family Turneraceae
                         family Violaceae
                   order Oxalidales
                         family Cephalotaceae
                         family Connaraceae
                         family Cunoniaceae
                         family Elaeocarpaceae
                         family Oxalidaceae
                         family Tremandraceae
                   order Rosales
                         family Barbeyaceae
                         family Cannabaceae
                         family Cecropiaceae
                         family Celtidaceae
                         family Dirachmaceae
                         family Elaeagnaceae
                         family Moraceae
                         family Rhamnaceae
                         family Rosaceae
                         family Ulmaceae
                         family Urticaceae
             clade eurosids II
                      family Tapisciaceae
                   order Brassicales
                         family Akaniaceae [+ family Bretschneideraceae]
                         family Bataceae
                         family Brassicaceae
                         family Caricaceae
                         family Emblingiaceae
                         family Gyrostemonaceae
                         family Koeberliniaceae
                         family Limnanthaceae
                         family Moringaceae
                         family Pentadiplandraceae
                         family Resedaceae
                         family Salvadoraceae
                         family Setchellanthaceae
                         family Tovariaceae
                         family Tropaeolaceae
                   order Malvales
                         family Bixaceae [+ family Diegodendraceae]
                         family Cistaceae
                         family Cochlospermaceae
                         family Dipterocarpaceae
                         family Malvaceae
                         family Muntingiaceae
                         family Neuradaceae
                         family Sarcolaenaceae
                         family Sphaerosepalaceae
                         family Thymelaeaceae
                   order Myrtales
                         family Alzateaceae
                         family Combretaceae
                         family Crypteroniaceae
                         family Heteropyxidaceae
                         family Lythraceae
                         family Melastomataceae
                         family Memecylaceae
                         family Myrtaceae
                         family Oliniaceae
                         family Onagraceae
                         family Penaeaceae
                         family Psiloxylaceae
                         family Rhynchocalycaceae
                         family Vochysiaceae
                   order Sapindales
                         family Anacardiaceae
                         family Biebersteiniaceae
                         family Burseraceae
                         family Kirkiaceae
                         family Meliaceae
                         family Nitrariaceae [+ family Peganaceae]
                         family Rutaceae
                         family Sapindaceae
                         family Simaroubaceae
          clade asterids
                order Cornales
                         family Cornaceae [+ family Nyssaceae]
                         family Grubbiaceae
                         family Hydrangeaceae
                         family Hydrostachyaceae
                         family Loasaceae
                order Ericales
                         family Actinidiaceae
                         family Balsaminaceae
                         family Clethraceae
                         family Cyrillaceae
                         family Diapensiaceae
                         family Ebenaceae
                         family Ericaceae
                         family Fouquieriaceae
                         family Halesiaceae
                         family Lecythidaceae
                         family Marcgraviaceae
                         family Myrsinaceae
                         family Pellicieraceae
                         family Polemoniaceae
                         family Primulaceae
                         family Roridulaceae
                         family Sapotaceae
                         family Sarraceniaceae
                         family Styracaceae
                         family Symplocaceae
                         family Ternstroemiaceae
                         family Tetrameristaceae
                         family Theaceae
                         family Theophrastaceae
             clade euasterids I
                      family Boraginaceae
                      family Plocospermataceae
                      family Vahliaceae
                   order Garryales
                         family Aucubaceae
                         family Eucommiaceae
                         family Garryaceae
                         family Oncothecaceae
                   order Gentianales
                         family Apocynaceae
                         family Gelsemiaceae
                         family Gentianaceae
                         family Loganiaceae
                         family Rubiaceae
                   order Lamiales
                         family Acanthaceae
                         family Avicenniaceae
                         family Bignoniaceae
                         family Buddlejaceae
                         family Byblidaceae
                         family Cyclocheilaceae
                         family Gesneriaceae
                         family Lamiaceae
                         family Lentibulariaceae
                         family Myoporaceae
                         family Oleaceae
                         family Orobanchaceae
                         family Paulowniaceae
                         family Pedaliaceae [+ family Martyniaceae]
                         family Phrymaceae
                         family Plantaginaceae
                         family Schlegeliaceae
                         family Scrophulariaceae
                         family Stilbaceae
                         family Tetrachondraceae
                         family Verbenaceae
                   order Solanales
                         family Convolvulaceae
                         family Hydroleaceae
                         family Montiniaceae
                         family Solanaceae
                         family Sphenocleaceae
             clade euasterids II
                      family Adoxaceae
                      family Bruniaceae
                      family Carlemanniaceae
                      family Columelliaceae [+ family Desfontainiaceae]
                      family Eremosynaceae
                      family Escalloniaceae
                      family Icacinaceae
                      family Polyosmaceae
                      family Sphenostemonaceae
                      family Tribelaceae
                   order Apiales
                         family Apiaceae
                         family Araliaceae
                         family Aralidiaceae
                         family Griseliniaceae
                         family Melanophyllaceae
                         family Pittosporaceae
                         family Torricelliaceae
                   order Aquifoliales
                         family Aquifoliaceae
                         family Helwingiaceae
                         family Phyllonomaceae
                   order Asterales
                         family Alseuosmiaceae
                         family Argophyllaceae
                         family Asteraceae
                         family Calyceraceae
                         family Campanulaceae [+ family Lobeliaceae]
                         family Carpodetaceae
                         family Donatiaceae
                         family Goodeniaceae
                         family Menyanthaceae
                         family Pentaphragmataceae
                         family Phellinaceae
                         family Rousseaceae
                         family Stylidiaceae
                   order Dipsacales
                         family Caprifoliaceae
                         family Diervillaceae
                         family Dipsacaceae
                         family Linnaeaceae
                         family Morinaceae
                         family Valerianaceae
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 Lissocarpaceae
    family Lophopyxidaceae
    family Medusandraceae
    family Metteniusaceae
    family Mitrastemonaceae
    family Paracryphiaceae
    family Pentaphylacaceae
    family Peridiscaceae
    family Plagiopteraceae
    family Pottingeriaceae
    family Sladeniaceae
    family Strasburgeriaceae
    family Tepuianthaceae