Cereus is a genus of large columnar cacti in the family Cactaceae, comprising approximately 33 accepted species. The plants are shrubby to tree-like in habit, often attaining heights of up to 15 meters (49 feet). Their stems are typically angled or distinctly ribbed, bearing large areoles with spines arranged along the ridges.
The genus was formally described by Philip Miller in 1754, making it one of the earliest-described cactus genera. The common vernacular name "Sweetpotato Cactus" reflects the edible qualities of certain species' fruit. Cereus belongs to the subfamily Cactoideae, tribe Cereeae, subtribe Cereinae within Cactaceae.
Flowers are large and funnelform, ranging from 9 to 30 cm in length. They are typically white, sometimes pink or purple, and characteristically open at night, relying on nocturnal pollinators such as moths. Fruits are globose to oblong with glossy black seeds. In C. repandus, the dark-red fruit has a mild, sweet-flavored white flesh.
The native range of the genus spans South America, including Brazil, northern Argentina, Paraguay, Uruguay, Bolivia, and parts of Venezuela, Colombia, Peru, Guyana, and Suriname. Several species have been widely cultivated outside this range and some have naturalized or become invasive in parts of Africa.
Etymology
The genus name Cereus comes from Greek (κηρός) and Latin words meaning "wax," "torch," or "candle." The term was first applied in botanical literature in a 1625 book by Tabernaemontanus and refers to the tall, candle-like appearance of the stems, particularly visible in the type species C. hexagonus.
Distribution
Cereus is native to South America, with its core range in Brazil, northern Argentina, Paraguay, Uruguay, and Bolivia. It also has occurrences in Peru, Colombia, Guyana, Suriname, and Venezuela. C. repandus, one of the more widespread species, is native to northern South America including Venezuela, as well as Caribbean islands such as Grenada and the Netherlands Antilles.
Certain species have naturalized or become invasive outside their native range, particularly in South Africa. The genus is also documented in the floristic record of the Southwestern United States and northern Mexico, where various historical species names have been applied. The genus is not recorded as naturalized in Australia.
Ecology
Cereus species are adapted to warm, arid, and semi-arid environments. In their native range they often grow in thickets and can form dominant features of the landscape. The night-blooming flowers — large, white or pale, funnelform, up to 30 cm long — are adapted for nocturnal pollination, primarily by moths and other nocturnal insects that are attracted by the pale petals and nectar. Fruit is fleshy and brightly colored, facilitating seed dispersal by birds and mammals.
Cultivation
Cereus species are widely cultivated as ornamental plants and hedging material in warm climates globally. They require full sun and well-drained soil, tolerating both sandy and loamy substrates at mildly acid to neutral pH. They are highly drought-tolerant but can also manage moderate moisture levels. Most species are suited to USDA hardiness zones 9–12, withstanding a few degrees of frost but not sustained freezes.
Growth is slow to moderate. Plants are suitable for container culture as well as in-ground planting. They are used as living fences and windbreaks. Flowers attract nocturnal pollinators, adding ecological value in cultivation settings.
Cultural Uses
The fruit of C. repandus (and related species) is edible, with a mild, sweet-flavored white flesh consumed raw. Fruit peels of some species can be candied. Young stems are occasionally eaten. The wood of Cereus species is used for furniture and as firewood. Stems have historically been sliced and used as a soap substitute. The genus is widely planted as living fencing across South America and in other warm regions where it has been introduced.
Propagation
Cereus species are propagated by seed. As with most cacti, seeds are generally sown in well-drained substrate under warm conditions. Vegetative propagation through stem cuttings is also widely practiced in cultivation.
Taxonomy
Cereus was formally described by Philip Miller in 1754, published in the fourth edition of his Gardeners Dictionary. The type species is Cereus hexagonus. The genus belongs to the family Cactaceae, subfamily Cactoideae, tribe Cereeae, subtribe Cereinae, within the order Caryophyllales.
The genus has a complex taxonomic history. Many columnar cactus genera that were once treated within a broadly circumscribed Cereus — including Cephalocereus, Pilosocereus, and Echinocereus — have since been separated into distinct genera as understanding of cactus phylogeny has improved. GBIF records 329 descendant taxa, reflecting both the breadth of historical usage and the current accepted species.
