In 1984, the International Organization for Succulent Plant Study set up a working party, now called the International Cactaceae Systematics Group, to produce a consensus classification of the cactus family, down to the level of genus. Their classification has been used as the basis for systems published since the mid-1990s. Treatments in the 21st century have generally divided the family into around 125–130 genera and 1,400–1,500 species, which are then arranged in a number of tribes and subfamilies. However, subsequent molecular phylogenetic studies have shown that a very high proportion of the higher taxa (genera, tribes and subfamilies) are not monophyletic, i.e. they do not contain all of the descendants of a common ancestor. As of March 2012, the internal classification of the family Cactaceae is uncertain and likely to change. A possible classification incorporating many of the insights from the molecular studies was produced by Nyffeler and Eggli in 2010.
The classification of the family Cactaceae remains uncertain as of March 2012. Since the mid-1990s, the system produced by the International Cactaceae Systematics Group (ICSG) of the International Organization for Succulent Plant Study has been used as the basis of many published classifications. Detailed treatments produced in the 21st century have divided the family into around 125–130 genera and 1,400–1,500 species, which are then arranged into a number of tribes and subfamilies.
The ICSG classification of the family recognizes four subfamilies: Pereskoideae (consisting only of the genus Pereskia), Opuntioideae, Maihuenioideae (consisting only of the genus Maihuenia) and Cactoideae. Molecular phylogenetic studies suggest that Pereskia is not monophyletic (i.e. its species are not the complete set of descendants of a common ancestor), although the three other subfamilies are. The Bayesian consensus cladogram from a 2005 study is shown below:
Five tribes have been recognized within the subfamily Opuntioideae: Tephrocacteae, Pterocacteae, Austrocylindropuntieae, Cylindropuntieae and Opuntieae. All but the first, Tephrocacteae, were shown to be "essentially monophyletic" in molecular phylogenetic study in 2009. A summary of the consensus Bayesian tree is shown below (tribes are bold; the number of species in the study is shown in parentheses).
Many of the genera within the Opuntioideae are not monophyletic. Maihueniopsis is highly polyphyletic, appearing in four separate lineages. The two largest genera within the subfamily, Opuntia and Cylindropuntia are also not monophyletic. The classification of the Opuntioideae is thus uncertain as of March 2012; Griffith and Porter say that changes in classification will require "broad information (of multiple data types) regarding all species of opuntioid cacti".
The ICSG classification divides the subfamily Cactoideae into nine tribes. However, phylogenetic research has not supported most of these tribes, nor even the genera of which they are composed. A 2011 study found that "an extraordinarily high proportion of genera" were not monophyletic, including 22 (61%) of the 36 genera in the subfamily Cactoideae sampled in the research. Of the nine tribes recognized within Cactoideae, one, Calymmantheae, comprises a single genus, Calymmanthium. Of the remaining eight, only two (Cacteae and Rhipsalideae) have been shown to be monophyletic. A summary of the cladograms for the Cactoideae presented in a 2011 paper is shown below (ICSG tribes in bold).
The classification of genera and tribes in the Cactaceae is thus likely to change in future.
Unless otherwise indicated, the subfamily placement of the genera listed here is based on Anderson's 2001 presentation of the ICSG classification, as is the tribal placement of the genera of the subfamily Cactoideae. The division of the subfamily Opuntioideae into tribes is additional to the ICSG system.
Pereskia Mill.
synonyms:
Peirescia Zucc. (orth. var.),
Peireskia Steud. (orth. var.),
Perescia Lem. (orth. var.),
Rhodocactus (A.Berger) F.M.Knuth
Austrocylindropuntia Backeb.
Cumulopuntia F.Ritter
Cylindropuntia (Engelm.) F.M.Knuth – chollas
Grusonia F.Rchb. ex Britton & Rose
including
Corynopuntia F.M.Knuth,
Micropuntia Daston
Pereskiopsis Britton & Rose
synonyms:
Peireskiopsis Vaupel (orth. var.)
Quiabentia Britton & Rose
Brasiliopuntia (K.Schum.) A.Berger
Consolea Lem.
Miqueliopuntia Fric ex F.Ritter
Opuntia Mill. – prickly pears
synonyms:
Airampoa Fric,
Cactodendron Bigelow, nom. inval.,
Cactus Lem.,
Chaffeyopuntia Fric & Schelle,
Clavarioidia Kreuz. (nom. inval.),
Ficindica St.-Lag.,
Nopalea Salm-Dyck,
Parviopuntia Soulaire & Marn.-Lap. (nom. inval.),
Phyllarthus Neck. ex M.Gómez (nom. inval.),
Salmiopuntia Fric (nom. inval.),
Subulatopuntia Fric & Schelle,
Tunas Lunell,
Weberiopuntia Fric
including
Nopalea Salm-Dyck
Tacinga Britton & Rose
Tunilla D.R.Hunt & Iliff
Pterocactus K.Schum.
Maihueniopsis Speg.
including
Puna R.Kiesling
Tephrocactus Lem.
synonyms:
Pseudotephrocactus Fric
Maihuenia (Phil. ex F.A.C.Weber) K.Schum.
Armatocereus Backeb.
Browningia Cárdenas, Gymnocereus Rauh & Backeb.
Jasminocereus Britton & Rose
Neoraimondia Britton & Rose
synonyms:
Neocardenasia Backeb.
Stetsonia Britton & Rose
Acharagma (N.P.Taylor) Glass
AriocarpusScheidw. – living rock
synonyms:
Anhalonium Lem.,
Neogomesia Castañeda,
Neogomezia Buxb. (orth. var.),
Roseocactus A.Berger,
Stromatocactus Karw. ex Rümpler (nom. inval.)
Astrophytum Lem.
synonyms:
Astrophyton Lawr. (orth. var.),
Maierocactus E.C.Rost
Aztekium Boed.
Cochemiea (K.Brandegee) Walton – see Mammillaria
Coryphantha (Engelm.) Lem. – beehive cactus
synonyms:
Aulacothele Monv. (nom. inval.),
Cumarinia Buxb.,
Glandulifera (Salm-Dyck) Fric,
Lepidocoryphantha Backeb.,
Roseia Fric (nom. inval.)
Echinocactus Link & Otto – barrel cactus
synonyms:
Brittonrosea Speg.,
Echinofossulocactus Lawr.,
Homalocephala Britton & Rose
Echinomastus Britton & Rose
Epithelantha F.A.C.Weber ex Britton & Rose – pingpong ball cactus
Escobaria Britton & Rose – foxtail cactus, pincushion cactus
synonyms:
Cochiseia W.H.Earle,
Escobesseya Hester,
Fobea Fric (nom. inval.),
Neobesseya Britton & Rose
Ferocactus Britton & Rose – barrel cactus
synonyms:
Bisnaga Orcutt,
Brittonia C.A.Armstr. (nom. inval.)
Geohintonia Glass & W.A.Fitz Maur.
Leuchtenbergia Hook.
Lophophora J.M.Coult. – peyote
Mammillaria Haw. – fishhook cactus, globe cactus, pincushion cactus, bird's-nest cactus
synonyms:
Bartschella Britton & Rose,
Cactus L.,
Chilita Orcutt,
Cochemiea (K.Brandegee) Walton,
Dolichothele (K.Schum.) Britton & Rose,
Ebnerella Buxb.,
Haagea Fric,
Krainzia Backeb.,
Lactomammillaria Fric (nom. inval.),
Leptocladia Buxb.,
Leptocladodia Buxb.,
Mamillaria F.Rchb. (orth. var.),
Mamillopsis (E.Morren) F.A.C.Weber ex Britton & Rose,
Mammariella Shafer (nom. inval.),
Mammilaria Torr. & A.Gray (orth. var.),
Neomammillaria Britton & Rose,
Oehmea Buxb.,
Phellosperma Britton & Rose,
Porfiria Boed.,
Pseudomammillaria Buxb.,
Solisia Britton & Rose
Mammilloydia Buxb.
Neolloydia Britton & Rose
synonyms:
Napina Fric (nom. inval.),
Pseudosolisia Y.Itô (nom. inval.)
Obregonia Fric
Ortegocactus Alexander
Pediocactus Britton & Rose – hedgehog cactus
synonyms:
Navajoa Croizat,
Pilocanthus B.W.Benson & Backeb.
Pelecyphora C.Ehrenb.
synonyms:
Encephalocarpus A.Berger
Sclerocactus Britton & Rose – fishhook cactus
synonyms:
Ancistrocactus Britton & Rose,
Coloradoa Boissev. & C.Davidson,
Glandulicactus Backeb.,
Toumeya Britton & Rose
Stenocactus (K.Schum.) A.W.Hill
synonyms:
Echinofossulocactus Britton & Rose,
Efossus Orcutt (orth. var.)
Strombocactus Britton & Rose
Thelocactus (K.Schum.) Britton & Rose
synonyms:
Hamatocactus Britton & Rose,
Thelomastus Fric (nom. inval.)
Turbinicarpus (Backeb.) Buxb. & Backeb. – top cactus
synonyms:
Gymnocactus Backeb.,
Normanbokea Kladiwa & Buxb.,
Rapicactus Buxb. & Oehme
Calymmanthium F.Ritter
synonyms:
Diploperianthium F.Ritter (nom. inval.)
Arrojadoa Britton & Rose
synonyms:
Pierrebraunia Esteves
Brasilicereus Backeb.
Cereus Mill. – sweet potato cactus
synonyms:
Mirabella F.Ritter,
Piptanthocereus (A.Berger) Riccob.,
Subpilocereus Backeb.
Cipocereus F.Ritter
synonyms:
Floribunda F.Ritter
Coleocephalocereus Backeb.
synonyms:
Buiningia Buxb.
Melocactus Link & Otto
synonyms:
Cactus Britton & Rose
Micranthocereus Backeb.
synonyms:
Austrocephalocereus Backeb.,
Siccobaccatus P.J.Braun & Esteves
Pilosocereus Byles & G. D. Rowley – tree cactus
synonyms:
Pilocereus K.Schum.,
Pseudopilocereus Buxb.
Praecereus Buxb.
Stephanocereus A.Berger
Uebelmannia Buining
Disocactus Lindl.
synonyms:
Aporocactus Lem.,
Aporocereus Fric & Kreuz. (orth. var.),
Bonifazia Standl. & Steyerm.,
Chiapasia Britton & Rose,
Disisocactus Kunze (orth. var.),
Disocereus Fric & Kreuz. (orth. var.),
Heliocereus (A.Berger) Britton & Rose,
Lobeira Alexander,
Mediocereus Fric & Kreuz. (orth. var.),
Nopalxochia Britton & Rose,
Pseudonopalxochia Backeb.,
Trochilocactus Linding.,
Wittia K.Schum.,
Wittiocactus Rauschert
Epiphyllum Haw. – climbing cactus
synonyms:
Phyllocactus Link,
Phyllocereus Miq.
Hylocereus (A.Berger) Britton & Rose – nightblooming cactus
synonyms:
Wilmattea Britton & Rose
Pseudorhipsalis Britton & Rose
Selenicereus (A.Berger) Britton & Rose – moonlight cactus, nightblooming cereus
synonyms:
Cryptocereus Alexander,
Deamia Britton & Rose,
Marniera Backeb.,
Mediocactus Britton & Rose,
Strophocactus Britton & Rose,
Strophocereus Fric & Kreuz. (orth. var.)
Weberocereus Britton & Rose
synonyms:
Eccremocactus Britton & Rose,
Eccremocereus Fric & Kreuz. (orth. var.),
Werckleocereus Britton & Rose
Austrocactus Britton & Rose
Blossfeldia Werderm.
Cintia Knize & Ríha
Copiapoa Britton & Rose
synonyms:
Pilocopiapoa F.Ritter
Eriosyce Phil.
synonyms:
Ceratistes Labour. (nom. inval.),
Chileniopsis Backeb.,
Chileocactus Fric (nom. inval.),
Chileorebutia Fric (nom. inval.),
Chiliorebutia Fric (orth. var.),
Delaetia Backeb.,
Dracocactus Y.Itô (nom. inval.),
Euporteria Kreuz. & Buining,
Hildmannia Kreuz. & Buining,
Horridocactus Backeb.,
Islaya Backeb.,
Neochilenia Backeb. ex Dölz,
Neoporteria Britton & Rose,
Neoporteria Backeb.,
Neotanahashia Y.Itô,
Nichelia Bullock (nom. inval.),
Pyrrhocactus (A.Berger) A.W.Hill,
Rodentiophila F.Ritter ex Backeb.,
Thelocephala Y.Itô
Eulychnia Phil.
synonyms:
Philippicereus Backeb.
Frailea Britton & Rose
Neowerdermannia Fric
Parodia Speg.
synonyms:
Acanthocephala Backeb.,
Brasilicactus Backeb.,
Brasiliparodia F.Ritter,
Brasilocactus Fric (nom. inval.),
Chrysocactus Y.Itô (nom. inval.),
Dactylanthocactus Y.Itô,
Eriocactus Backeb.,
Eriocephala Backeb.,
Friesia Fric (nom. inval.),
Hickenia Britton & Rose,
Malacocarpus Salm-Dyck,
Microspermia Fric,
Neohickenia Fric,
Notocactus (K.Schum.) Fric,
Sericocactus Y.Itô,
Wigginsia D.M.Porter
Yavia R.Kiesling & Piltz
Acanthocereus (Engelm. ex A.Berger) Britton & Rose – triangle cactus
synonyms:
Dendrocereus Britton & Rose,
Monvillea Britton & Rose
Bergerocactus Britton & Rose – snake cactus
synonyms:
Bergerocereus Fric & Kreuz. (orth. var.)
Carnegiea Britton & Rose – saguaro
Cephalocereus Pfeiff. – old man cactus
synonyms:
Haseltonia Backeb.,
Neodawsonia Backeb.,
Pilocereus Lem.
Corryocactus Britton & Rose
synonym:
Corryocereus Fric & Kreuz. (orth. var.),
Erdisia Britton & Rose,
Eulychnocactus Backeb. (nom. inval.)
Dendrocereus Britton & Rose – see Acanthocereus
Echinocereus Engelm. – hedgehog cactus
synonyms:
Morangaya G.D.Rowley,
Wilcoxia Britton & Rose
Escontria Rose
Isolatocereus Backeb. – see Stenocereus
Leptocereus (A.Berger) Britton & Rose
synonyms:
Neoabbottia Britton & Rose
×Myrtgerocactus Moran
[=
Myrtillocactus ×
Bergerocactus]
Myrtillocactus Console
synonyms:
Myrtillocereus Fric & Kreuz. (orth. var.)
Neobuxbaumia Backeb.
synonyms:
Pseudomitrocereus Bravo & Buxb.,
Rooksbya Backeb.
×Pacherocactus G.D.Rowley
[=
Pachycereus ×
Bergerocactus]
Pachycereus (A.Berger) Britton & Rose
synonyms:
Backebergia Bravo,
Lemaireocereus Britton & Rose,
Lophocereus (A.Berger) Britton & Rose,
Marginatocereus (Backeb.) Backeb.,
Mitrocereus (Backeb.) Backeb.,
Pterocereus T.MacDoug. & Miranda
Peniocereus (A.Berger) Britton & Rose
synonyms:
Cullmannia Distefano,
Neoevansia W.T.Marshall,
Nyctocereus (A.Berger) Britton & Rose
Polaskia Backeb.
synonyms:
Chichipia Backeb. (nom. inval.),
Heliabravoa Backeb.
Pseudoacanthocereus F.Ritter
Stenocereus (A.Berger) Riccob.
synonyms:
Hertrichocereus Backeb.,
Isolatocereus Backeb.,
Isolatocereus (Backeb.) Backeb.,
Machaerocereus Britton & Rose,
Marshallocereus Backeb.,
Neolemaireocereus Backeb.,
Rathbunia Britton & Rose,
Ritterocereus Backeb.
Hatiora Britton & Rose
synonyms:
Epiphyllopsis Backeb. & F.M.Knuth,
Hariota DC.,
Pseudozygocactus Backeb.,
Rhipsalidopsis Britton & Rose
Lepismium Pfeiff.
synonyms:
Acanthorhipsalis (K.Schum.) Britton & Rose,
Acanthorhipsalis Kimnach,
Pfeiffera Salm-Dyck
Rhipsalis Gaertn.
synonyms:
Cassytha Mill.,
Erythrorhipsalis A.Berger,
Hariota Adans.,
Lymanbensonia Kimnach
Schlumbergera Lem. – Christmas cactus, Easter cactus
synonyms:
Epiphyllanthus A.Berger,
Epiphyllum Pfeiff.,
Opuntiopsis Knebel (nom. inval.),
Zygocactus K.Schum.,
Zygocereus Fric & Kreuz. (orth. var.)
Acanthocalycium Backeb.
synonyms:
Spinicalycium Fric (nom. inval.)
Arthrocereus A.Berger
Brachycereus Britton & Rose
Cleistocactus Lem.
synonyms:
Akersia Buining,
Bolivicereus Cárdenas,
Borzicactella H.Johnson ex F.Ritter,
Borzicactus Riccob,
Borzicereus Fric & Kreuz. (orth. var.),
Cephalocleistocactus F.Ritter,
Cleistocereus Fric & Kreuz. (orth. var.),
Clistanthocereus Backeb.,
Demnosa Fric,
Gymnanthocereus Backeb.,
Hildewintera F.Ritter,
Loxanthocereus Backeb.,
Maritimocereus Akers,
Pseudoechinocereus Buining (nom. inval.),
Seticereus Backeb.,
Seticleistocactus Backeb.,
Winteria F.Ritter,
Winterocereus Backeb.
Cephalocleistocactus F.Ritter – see Cleistocactus
Denmoza Britton & Rose
Discocactus Pfeiff.
Echinopsis Zucc. – San Pedro cactus
synonyms:
Acantholobivia Backeb.,
Acanthopetalus Y.Itô,
Andenea Fric (nom. inval.),
Aureilobivia Fric, nom. inval.,
Chamaecereus Britton & Rose,
Chamaelobivia Y. Itô (nom. inval.),
Cinnabarinea Fric ex F.Ritter,
Echinolobivia Y.Itô (nom. inval.),
Echinonyctanthus Lem.,
Furiolobivia Y.Itô (nom. inval.),
Helianthocereus Backeb,
Heterolobivia Y.Itô (nom. inval.),
Hymenorebulobivia Fric (nom. inval.),
Hymenorebutia Fric ex Buining,
Leucostele Backeb.,
Lobirebutia Fric (nom. inval.),
Lobivia Britton & Rose,
Lobiviopsis Fric (nom. inval.),
Megalobivia Y.Itô (nom. inval.),
Mesechinopsis Y.Itô,
Neolobivia Y.Itô,
Pilopsis Y.Itô (nom. inval.),
Pseudolobivia (Backeb.) Backeb.,
Rebulobivia Fric (nom. inval.),
Salpingolobivia Y.Itô,
Scoparebutia Fric & Kreuz. ex Buining,
Setiechinopsis (Backeb.) de Haas,
Soehrensia Backeb.,
Trichocereus (A.Berger) Riccob.
Espostoa Britton & Rose
synonyms:
Binghamia Britton & Rose,
Pseudoespostoa Backeb.,
Thrixanthocereus Backeb.,
Vatricania Backeb.
Espostoopsis Buxb.
synonyms:
Gerocephalus F.Ritter
Facheiroa Britton & Rose
synonyms:
Zehntnerella Britton & Rose
Gymnocalycium Pfeiff. ex Mittler – chin cactus
synonyms:
Brachycalycium Backeb.
Haageocereus Backeb.
synonyms:
Floresia Krainz & F.Ritter ex Backeb. (nom. inval.),
Haageocactus Backeb. (nom. inval.),
Lasiocereus F.Ritter,
Neobinghamia Backeb.,
Peruvocereus Akers
×Haagespostoa G.D.Rowley
[=
Haageocereus ×
Espostoa]
Harrisia Britton – apple cactus
synonyms:
Eriocereus (A.Berger) Riccob.,
Roseocereus Backeb.
Lasiocereus F.Ritter – see Haageocereus
Leocereus Britton & Rose
Matucana Britton & Rose
synonyms:
Eomatucana F.Ritter
Mila Britton & Rose
Oreocereus (A.Berger) Riccob.
synonyms:
Arequipa Britton & Rose,
Arequipiopsis Kreuz. & Buining,
Morawetzia Backeb.,
Submatucana Backeb.
Oroya Britton & Rose
Pygmaeocereus H.Johnson & Backeb.
Rauhocereus Backeb.
Rebutia K.Schum.
synonyms:
Aylostera Speg.,
Bridgesia Backeb.,
Cylindrorebutia Fric & Kreuz.,
Digitorebutia Fric & Kreuz.,
Echinorebutia Fric (nom. inval.),
Eurebutia Fric (nom. inval.),
Gymnantha Y.Itô,
Mediolobivia Backeb.,
Mediorebutia Fric (nom. inval.),
Neogymnantha Y.Itô,
Reicheocactus Backeb.,
Setirebutia Fric & Kreuz. (nom. inval.),
Spegazzinia Backeb.,
Sulcorebutia Backeb.,
Weingartia Werderm.
Samaipaticereus Cárdenas
Weberbauerocereus Backeb.
synonyms:
Meyenia Backeb.
Yungasocereus F.Ritter
