Genus of plant in the family Cactaceae
Peniocereus is a genus of vining cacti, comprising about 18 species, found from the southwestern United States and Mexico. 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" 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.
 ;templatestyles src="Reflist/styles.css" / ;