''Acanthocalycium'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

cactus A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...

consisting of several species from

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

and

Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...

. The taxon name comes from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''akantha'' (meaning ''prickly'') and ''kalyx'' (meaning ''buds''), which refers to the spines on the

floral tube In angiosperms, a hypanthium or floral cup is a structure where basal portions of the calyx, the corolla, and the stamens form a cup-shaped tube. It is sometimes called a floral tube, a term that is also used for corolla tube and calyx tube."Lec ...

Description

These plants are

globose This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

to elongate, with numerous ribs on the spiny stems columnar stem succulents up to 60 cm high and 20 cm in diameter. The plants usually remain unbranched or branch slightly from the bases. The areoles, which stand on up to 20 ribs, have many spines up to about 8 cm long, which are only indistinctly divided into edge and central spines.

Flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s range from yellow to orange or white to pink or magenta and open during the day. The funnel-shaped flowers, formed by areoles near the apex, have scales on the outside that taper into sharp thorns. This feature is typical of the genus Acanthocalycium and only occurs in it. Inside, the area of the flower containing the ovary (ovary) is protected with a ring of hairs.

Taxonomy

''Spinicalycium''

Fric The Royal Institute of Chemistry was a British scientific organisation. Founded in 1877 as the Institute of Chemistry of Great Britain and Ireland (ICGBI), its role was to focus on qualifications and the professional status of chemists, and its ai ...

(nom. inval.) has been brought into

synonymy A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with this genus. Besides, the genus ''Acanthocalycium'' has been periodically included in the genus ''

Echinopsis ''Echinopsis'' is a genus of Cactus, cacti native plant, native to South America, sometimes known as hedgehog cactus, sea-urchin cactus or Easter lily cactus. , there are about 20 accepted species, ranging from large and treelike types to small ...

''.

Species

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

accepted the following species:

References

* Edward F. Anderson, ''The Cactus Family'' (Timber Press, 2001), pp. 105–106 * Willy Cullmann, Erich Götz & Gerhard Gröner, ''The Encyclopedia of Cacti'' (Alphabooks, 1086). pp. 124–125 {{Taxonbar, from=Q133858 Cereeae genera