Selenicereus (A.Berger) Britton & Rose is a genus of approximately 28–45 climbing and epiphytic cacti in the family Cactaceae, subfamily Cactoideae, tribe Hylocereeae. The genus was first described as a section by Alwin Berger in 1905 and raised to genus rank by Nathaniel Lord Britton and Joseph Nelson Rose in 1909. A significant taxonomic revision in 2017 brought the formerly separate genus Hylocereus — along with Werckleocereus, Wilmattea, Cryptocereus, and several other segregate genera — into synonymy with Selenicereus, substantially enlarging the genus.
Plants are vinelike shrubs, growing as scandent, terrestrial, hemi-epiphytic, epiphytic, or epipetric forms. Stems are typically bright green to bluish-green, 100–500 cm long and 0.8–5 cm in diameter, bearing 3–8 ribs with small woolly areoles spaced 10–25 mm apart and 1–18 spines per areole. Aerial roots are produced along the climbing stems. The flowers are among the most striking in the cactus family: large, nocturnal, and intensely fragrant, with floral tubes 12–40 cm long, generally white, and lasting only a single night. Pollination is accomplished primarily by moths and occasionally by bats. Fruits are red and spherical, 5–9 cm in diameter, with black shiny seeds.
The genus is native to Mexico, Central America, the Caribbean, and much of South America, extending from Texas south to Argentina and Bolivia. Several species have been widely introduced across tropical and subtropical regions worldwide, from the Mediterranean to Southeast Asia and the Pacific Islands, primarily driven by cultivation for their edible fruit. The common name "moonlight cactus" refers to the nocturnal flowering habit encoded in the genus name, which combines the Ancient Greek selḗnē (moon) with Latin cēreus (candle).
Selenicereus is best known commercially for producing dragon fruit (pitaya or pitahaya): S. undatus yields white-fleshed fruit, S. megalanthus the yellow-skinned variety, and S. costaricensis red-fleshed fruit. These are widely cultivated across the Americas, Europe, and Asia.
Etymology
The genus name Selenicereus combines the Ancient Greek selḗnē (σελήνη, moon) with Latin cēreus (candle), a reference to the genus's defining characteristic: large, white, fragrant flowers that open only at night. This nocturnal flowering habit also gives rise to the most widely used English common name, "moonlight cactus," as well as the poetic "queen of the night" applied to S. grandiflorus in particular. The genus was first circumscribed as a section by Alwin Berger in 1905 and formally published at genus rank by Britton & Rose in 1909.
Distribution
Selenicereus has a native range extending from Texas (USA) and Mexico through all of Central America and the Caribbean — including the Bahamas, Cuba, Jamaica, Hispaniola, Puerto Rico, Trinidad-Tobago, and the Lesser Antilles — south through Colombia, Venezuela, the Guianas, Brazil (all major regions), Ecuador, Peru, Bolivia, Paraguay, and northeastern Argentina. Mexico is particularly well represented, with occurrences in all major regions.
Through cultivation of dragon-fruit species, the genus has been introduced widely: in Europe (Canary Islands, Madeira, Baleares, Sardinia, Sicily), Africa (Cape Provinces and KwaZulu-Natal in South Africa, Tunisia, Comoros, Cape Verde, Mauritius, Réunion), Asia (China, Taiwan, Vietnam, Myanmar, Cambodia, Hainan, Bangladesh), and Oceania (New Caledonia, Vanuatu, Niue, Galápagos). In North America, naturalized populations occur in Florida and Hawaii. Distribution data source: World Checklist of Vascular Plants (WCVP).
Ecology
Plants in Selenicereus span a wide range of growth strategies: scandent, terrestrial, hemi-epiphytic, epiphytic, and epipetric (rock-dwelling) forms all occur within the genus. The climbing habit is supported by adventitious aerial roots produced along the stems. Flowers are exclusively nocturnal and pollinated predominantly by moths, with bats also serving as pollinators in some species.
The population biology of the genus remains poorly understood. In North American populations it is unclear whether persistence is maintained solely by vegetative spread or also involves regular sexual reproduction; the long-term viability of individual species in this region has not been fully evaluated.
Cultivation
Selenicereus species, particularly the dragon-fruit species formerly in Hylocereus, are among the most economically important cacti in global horticulture and commercial agriculture. They are widely cultivated across tropical and subtropical regions of the Americas, Europe, and Asia for their edible fruits — known as pitaya or pitahaya in Spanish and as dragon fruit in English. Selenicereus undatus (white-fleshed dragon fruit), S. megalanthus (yellow dragon fruit), and S. costaricensis (red-fleshed) are the principal commercial types. S. setaceus is harvested and eaten in South America. Plants may be sourced from wild collections or grown in orchards and gardens.
Cultural uses
The fruit of several Selenicereus species is a major food crop marketed globally as dragon fruit. Under Spanish names pitaya or pitahaya, the fruit has long been collected from wild plants and cultivated in Latin America. Commercial cultivation is now extensive across Asia (particularly Vietnam and China), contributing to mainstream international availability. S. setaceus fruits are also consumed in South America. Beyond food, the genus's spectacular nocturnal blooms — especially those of S. grandiflorus — have historically been celebrated as ornamentals and used in traditional herbal preparations in parts of Latin America.
Taxonomy
Selenicereus was originally described as a section by Alwin Berger in 1905 and elevated to genus status by Britton & Rose in 1909 (Contrib. USA Natl. Herb. 12: 429). The genus belongs to Cactaceae, subfamily Cactoideae, tribe Hylocereeae, within the hylocereoid clade of climbing and epiphytic cacti.
A sweeping 2017 revision brought Hylocereus Britton & Rose (1909) — the genus that contains the commercially important dragon-fruit cacti — into synonymy with Selenicereus, along with seven other previously recognized genera: Werckleocereus, Wilmattea, Cryptocereus, Chiapasophyllum, Cereaster, Cladoblasia, and Hyalocereus. The genus was also expanded to absorb species formerly placed in Mediocactus, Deamia, and Strophocactus. GBIF records 45 descendant taxa under the consolidated genus; pre-merger treatments recognized approximately 28 species.
