The lava cactus is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

cactus 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 Gree ...

, ''Brachycereus nesioticus'', the sole species of the

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 ...

''Brachycereus''. The plant is a colonizer of

lava field Lava fields are large, mostly flat areas of surface or subaquatic lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or hundreds of miles across the underlying terrain. Morphology and stru ...

s – hence its common name – where it forms spiny clumps up to tall. Its solitary white or yellowish white flowers open in the daytime. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the

Galápagos Islands The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...

Description

The lava cactus is a leafless clump-forming species, with cylindrical stems typically up to tall in formations that can be as much as across. The stems have 16–22 ribs and are yellow, with green or brown tones. Each

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 ...

has up to 40 spines, up to long, initially yellowish, but becoming darker with age. The flowers are borne singly, and are narrowly funnel-shaped, up to long and across, with many spines on the lower part of the flower. They open in the daytime and are white to yellowish white inside. The remains of the flower stay attached to the fruit, which is a berry, red to brown in colour, covered with yellow spines and filled with many black seeds. Brachycereus nesioticus with flower remains

Brachycereus nesioticus with flower remains

Taxonomy

The species was first described in 1902 as '' Cereus nesioticus'' by

Karl Moritz Schumann Karl Moritz Schumann (17 June 1851 – 22 March 1904) was a German botanist. Schumann was born in Görlitz. He was curator of the Botanisches Museum in Berlin-Dahlem from 1880 until 1894. He also served as the first chairman of the ''Deutsc ...

in an account of the flora of Galápagos authored by

Benjamin Lincoln Robinson Benjamin Lincoln Robinson (November 8, 1864 – July 27, 1935) was an American botanist. Biography Robinson was born on November 8, 1864, in Bloomington, Illinois. In 1887, he received an A.B. from Harvard. He married Margaret Louise Casson on ...

. In 1920,

Nathaniel Lord Britton Nathaniel Lord Britton (January 15, 1859 – June 25, 1934) was an American botanist and taxonomist who co-founded the New York Botanical Garden in the Bronx, New York. Early life Britton was born in New Dorp in Staten Island, New York to Jasp ...

and

Joseph Nelson Rose Joseph Nelson Rose (January 11, 1862 – May 4, 1928) was an American botanist. He was born in Union County, Indiana. His father died serving during the Civil War when Joseph Rose was a young boy. He later graduated from high school in Libert ...

erected the genus ''Brachycereus'', synonymizing ''Cereus nesioticus'' and another cactus from the Galápagos, ''Cereus thouarsii'', under the name ''Brachycereus thouarsii''. In 1935,

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 ...

realized that only ''Cereus nesioticus'' belonged in ''Brachycereus'' (later placing ''Cereus thouarsii'' in '' Jasminocereus''.) ''Brachycereus'' means "short cereus"; ''nesioticus'' is derived from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

νησιωτικός, meaning "of the islands".

Phylogeny and classification

Molecular studies show that the two endemic Galápagos genera, ''Brachycereus'' and ''Jasminocereus'', are sisters, with their closest relative being the South American mainland species ''Armatocereus'': In one widely used classification of cacti, ''Brachycereus'' is placed in the tribe Trichocereeae of 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 in ...

, while ''Armatocereus'' and ''Jasminocereus'' are placed in the tribe Browningieae, which is inconsistent with the cladogram above. A classification produced in 2010 by Nyffeler and Eggli puts all three genera in a much larger tribe Phyllocacteae.

Distribution and habitat

The lava cactus is

to the Galápagos, where is found on Fernandina,

Genovesa Genovesa Island ( Spanish: ''Isla Genovesa''), referred to in English as Tower Island, is a shield volcano in the Galápagos Islands in the eastern Pacific Ocean. The island occupies about , and its maximum elevation is . The horse-shoe shaped ...

, Isabela, Pinta, Santa Cruz, and

Santiago Santiago (, ; ), also known as Santiago de Chile, is the capital and largest city of Chile as well as one of the largest cities in the Americas. It is the center of Chile's most densely populated region, the Santiago Metropolitan Region, whos ...

, as well as some smaller islands, including Bartolomé. It grows on barren lava flows, both

pāhoehoe Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

and

ʻaʻā Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

. It is one of the first species to grow on new lava flows.

Conservation

''Brachycereus nesioticus'' was rated as "vulnerable" in the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

of 2000, but this was downgraded to "least concern" in 2013. As with all plants and animals of the Galápagos, collecting or disturbing the lava cactus is strictly controlled by the Ecuadorian government; the complete range of the species lies within the Galápagos National Park and Natural World Heritage Site. Trade in the species is controlled under

CITES Appendix II CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...

References

External links

Arkive.org: photos
{{Taxonbar, from=Q134991 Cacti of South America Endemic flora of Galápagos