''Armatocereus'' (from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''armatus'', "armed" and ''cereus'', "pliant/soft") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of mostly tree-like cacti from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

(

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...

and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

). These species have a conspicuous constriction at the end of the annual growth. The flowers are mostly white, with a more or less spiny ovary. The fruits are mostly spiny.

Description

''Armatocereus'' species are columnar cacti, bushlike or treelike, with cylindrical upright branched stems. The stems have 5–12 distinct ribs, and are made up of sections with a narrower "neck" between them, corresponding to annual growth. The large

areole In botany, areoles are small light- to dark-colored bumps on cacti out of which grow clusters of spines. Areoles are important diagnostic features of cacti, and identify them as a family distinct from other succulent plants. Gordon Rowley - W ...

s bear strong spines, rarely few or none. The narrow tubular flowers appear at night, and have a spiny ovary and floral tube and white petals (red in '' A. rauhii''). The red or green fruit is large, globular or ovoid, with strong spines that are lost on maturity. It contains large black seeds, ovoid or kidney-shaped.

Taxonomy

The genus name was first mentioned in print by

Curt Backeberg Curt Backeberg (2 August 1894 in Lüneburg, Germany – 14 January 1966) was a German horticulturist especially known for the collection and classification of cacti. Biography He travelled extensively through Central and South America, and publis ...

in 1934, and again in 1935. However, at the time, the

International Code of Botanical Nomenclature The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "trad ...

required a Latin description for a genus name to be accepted, and this was not published until 1938. ''Armatocereus'' means "armed cereus", referring to the spines.

Phylogeny and classification

Classifications based on morphological characters placed ''Armatocereus'' in the subfamily Cactoideae, tribe Browningieae. However, molecular phylogenetic studies have repeatedly shown that the tribe Browningieae is not monophyletic (like most other traditional cactus tribes). A 2011 study places ''Armatocereus'' in a clade called "PHB", as it contains members of the previously defined tribes Pachycereeae, Hylocereeae and Browningieaes; other Browningieae members, including '' Browningia'', are placed in a more distantly related BCT clade. The main clades in the resulting phylogeny are shown below.

Species

The taxonomy of the genus and of its species was described as "confusing" by Edward F. Anderson in 2001. The Plant List (version 1.1, September 2013) accepts six species: Other sources, including Anderson (2001), list further species not accepted in The Plant List: *''Armatocereus arduus'' F.Ritter = ''A. rauhii'' *''Armatocereus ghiesbreghtii'' (K.Schum.) F.Ritter – status unresolved in The Plant List *''Armatocereus mataranus'' F.Ritter = ''A. matucanensis'' *''Armatocereus oligogonus'' Rauh & Backeb. = ''A. matucanensis'' *''Armatocereus riomajensis'' Rauh & Backeb. = ''A. matucanensis'' *''Armatocereus rupicola'' F.Ritter = ''A. rauhii''

Distribution and habitat

The genus is found in

and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

, with most species occurring in Peru. (Older sources include ''

Stenocereus humilis ''Stenocereus'' ( Gk. ''stenos'', narrow, L. ''cereus'', candle) is a genus of columnar or tree-like cacti from the Baja California Peninsula and other parts of Mexico, Arizona in the United States, Colombia, Costa Rica, Guatemala, Venezuela an ...

'' in the genus, which occurs in Columbia.)

References

{{Taxonbar, from=Q133868 Cactoideae genera Cacti of South America Flora of Ecuador Flora of Peru