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.
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The APG system was superseded in 2003 by a revision, the APG II system, in 2009 by a next revision, the APG III system, and then in 2016 by a further revision, the APG IV system.
The main groups in the system (all unranked clades) are:
monocots
core eudicots
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:
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.
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