The Echinocereeae are a tribe of

cacti A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

in the subfamily

Cactoideae The Cactoideae are the largest subfamily of the cactus family, Cactaceae. Around 80% of cactus species belong to this subfamily. , the internal classification of the family Cactaceae remained uncertain and subject to change. A classification inc ...

. Since 2006, the tribe has included the former tribe Pachycereeae in many treatments of cactus classification. The exact

circumscription Circumscription may refer to: *Circumscribed circle *Circumscription (logic) *Circumscription (taxonomy) * Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthrop ...

of the tribe has been subject to considerable change, particularly since

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

approaches have been used in determining classifications, and remains uncertain. The tribe includes large treelike species, such as the

saguaro The saguaro (, ) (''Carnegiea gigantea'') is a tree-like cactus species in the monotypic genus ''Carnegiea'' that can grow to be over tall. It is native to the Sonoran Desert in Arizona, the Mexican state of Sonora, and the Whipple Mountains a ...

(''Carnegiea gigantea''), as well as shorter shrubby species. Most members of the tribe are found in desert regions, particularly in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

and the southwestern United States.

Description

The tribe includes large treelike species, as well as shorter shrubby species. Some species can grow to be over tall, like the

(''Carnegiea gigantea'') and '' Neobuxbaumia macrocephala''. Their stems are ribbed and columnar, not divided into segments. Most have flowers that open at night.

Taxonomy

In 1958, Franz Buxbaum published a division into tribes of what is now the subfamily Cactoideae, then Cereoideae. Two of these tribes were Pachycereeae (which he spelt "Pachycereae") and Echinocereeae (which he spelt "Echinocereae"). Pachycereeae was a newly published taxon; Echinocereeae was an elevation of the subtribe Echinocereinae ("Echinocereanae") established by Britton and Rose in 1922. Studies based on

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

DNA showed that ''Echinocereus'', the type genus of the Echinocereeae, was nested within the Pachycereeae, as then

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 polyg ...

, and Pachycereeae was expanded to include Echinocereeae. In 2006, David Hunt and the International Cactaceae Systematics Group used the name Echinocereeae rather than Pachycereeae for the tribe. This has been followed in much subsequent work, including a major 2011

analysis of the family Cactaceae. However, some authors continue to use the name Pachycereeae for the tribe.

Phylogeny

Genera placed at one time or another within the Echinocereeae (or Pachycereeae) fell within the "Core Cactoideae I" clade in the 2011 molecular phylogenetic study by Barcenas et al. Possible phylogenetic relationships within this clade are shown in the cladogram below, based on Guerrero et al. (2019) and revisions to the Hylocereeae in 2017 and 2020.

Genera

"Core Echinocereeae" recovered in molecular phylogenetic analyses in 2005 and 2011 contains the following genera, often only in part compared to earlier generic circumscriptions. Some genera were further placed in two subtribes, Pachycereinae and Echinocereinae. The 2011 study found the tribe

Hylocereeae The Hylocereeae are a tribe of cacti. Most are found in the tropical forests of Central and northern South America, and are climbers or epiphytes, unlike most cacti. The tribe includes between six and eight genera in different circumscriptions ...

to be embedded within a wider Echinocereeae, but studies in 2017 and 2020 asserted the independence of the Hylocereeae, including within it two genera placed within Pachycereeae in earlier classifications: ''

Acanthocereus ''Acanthocereus'' is a genus of cactus, cacti. Its species take the form of shrubs with arching or climbing stems up to several meters in height. The generic name is derived from the Greek language, Greek word ''άκανθα'' (''acantha''), me ...

'' and ''Pseudoacanthocereus'' (sunk into ''

Strophocactus ''Strophocactus'' is a genus of cacti in the subfamily Cactoideae. Its status and circumscription remain somewhat uncertain, with the genus containing one to three species (not always the same ones). Molecular phylogenetic data suggest that it co ...

'').

Distribution and habitat

Members of the Echinocereeae are native from the southwestern United States, through

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

and the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

to northern South America. Many are classic columnar desert cacti of Mexico and the southwestern US, like the saguaro (''Carnegiea gigantea''). A few have a wider distribution: ''

Stenocereus griseus ''Stenocereus griseus'', also known as the Mexican organ pipe, dagger cactus, pitaya, and pitayo de mayo, is a species of cactus. Description This tree-like cactus can grow up to 9 m tall, with stems up to 12 cm in diameter. Depending on t ...

'' is found from northeastern Mexico to

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

References

{{taxonbar, from1=Q987500, from2=Q137797 Caryophyllales tribes