''Peniocereus'' 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 vining
cacti, comprising about 18
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 ...
, found from the southwestern
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
and
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 ...
. They have a large underground tuber, thin and inconspicuous stems.
Its name comes from the prefix ''penio-'' (from the Latin ''penis'', meaning ‘tail’) and ''
Cereus'', the large genus from which it was split.
Known as the desert night-blooming cereus, it also shares its common names of "
night-blooming cereus
Night-blooming cereus is the common name referring to a large number of flowering ceroid cacti that bloom at night. The flowers are short lived, and some of these species, such as ''Selenicereus grandiflorus'', bloom only once a year, for a s ...
" and "queen of the night" with many other similar cacti.
Taxonomy
''Peniocereus'' was first described in 1905 by Alwin Berger as a subgenus of ''Cereus'' with a single species, ''Cereus greggii''. This taxon was elevated to the genus level as ''Peniocereus greggii'' by Britton and Rose in 1909. Later in 1974 an infrageneric classification was constructed based on morphological features that split ''Peniocereus'' into two subgenera: ''Peniocereus'' and ''Pseudoacanthocereus''. In 2005 a molecular phylogenetic study of the genus supported this split and showed that ''Peniocereus'' is not monophyletic.
Species
Species include:
Subgenus ''Peniocereus''
Molecular phylogeny supported the position of this subgenus within ''Echinocereeae''.
''Nyctocereus''
The 2005 molecular study showed that ''P. serpentinus'' is in ''Echinocereeae'' along with subgenus ''Peniocereus'', but suggests resurrecting the monotopic ''Nyctocereus'' as it is sister to ''Bergerocactus''.
Subgenus ''Pseudoacanthocereus''
Molecular phylogeny and morphological evidence suggests this subgenus is more closely related to ''Acanthocereus''.
References
Cactoideae genera
Cacti of Mexico
Cacti of the United States
Flora of the Southwestern United States
Flora of the Sonoran Deserts
Night-blooming plants
Taxa named by Alwin Berger
Taxa named by Nathaniel Lord Britton
Taxa named by Joseph Nelson Rose
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