Selenicereus grandiflorus, the queen of the night, is an epiphytic and lithophytic cactus. Its flowers are 17 to 22.5 cm long and reportedly as much as 38 cm wide. The plant flowers in late spring or early summer and blooms only one night a year.
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The plant is native throughout the Greater Antilles (Cuba, Cayman Islands, Puerto Rico, Jamaica, the Dominican Republic and Haiti), Mexico, Guatemala, Belize, Honduras and Nicaragua. It is found climbing on trees and on rocks at an altitude of 700 metres. The stems are scandent, clambering or sprawling, and reach 10 m long or more. The plant takes two to three years to begin producing blooms. It should not be kept under 5 °C (41 °F) in winter.
The true species is extremely rare in cultivation. Most of the plants under this name belong to other species or hybrids. The names queen of the night and night-blooming cereus are also used for other species.
The genus name Selenicereus comes from Selene, the Greek moon goddess, and cereus, Latin for candle, and refers to the nocturnal flowers. Flowers of the genus are large and nocturnal, and may be pollinated by moths and bats. They are typically white and very fragrant, and in most species they last a single night. A number of Selenicereus species produce fruit that is eaten, known as pitaya or pitahaya in Spanish or as dragon fruit.
Plant and stems
The stems branch, sometimes form tangles, produce aerial roots and are stiff. They are usually 15 to 25 mm thick and carry 7 to 8 low ribs, separated by broad, rounded intervals. The areoles are small and carry white or greyish white wool. Each areole bears 5 to 18 spines, 4.5 to 12 mm long, which are yellowish brown to brownish or yellow, grey with age, and eventually fall. Juvenile plants have shorter and fewer spines. The epidermis is glaucous green or bluish green, often purplish, and smooth. The stems are extremely variable, especially in Jamaica, and margins from slightly wavy to strongly knobby can occur on the same plant, which causes confusion in cultivation.
The flower
The pericarpel is 25 mm long and bears strap-shaped, yellowish bracteoles 5 mm long, covered with nearly white or tawny hairs and sharp bristles. The receptacle measures 7.5 to 8.7 cm. The outer tepals are 7.5 to 10 cm long, light brown, salmon to pink buff, and yellowish on the upper surface. The inner tepals are white, lanceolate and narrow gradually into a pointed apex. The stamens are white and 38 to 50 mm long, with yellowish anthers 1.5 mm long. The style is 15 to 20 cm long, often longer than the inner tepals, and ends in 7 to 12 slender stigma lobes. Flowers of the genus are generally produced in abundance on mature plants.
Names and classification
The epithet grandiflorus is Latin for 'large flowered'. The species is often confused with the genus Epiphyllum. Its conservation status is Least Concern.
Three subspecies are recognized: ssp. grandiflorus, ssp. donkelaarii from Mexico and ssp. hondurensis. Subspecies donkelaarii has low-ribbed stems 1 cm thick with short spines and flowers 18 cm long, while subspecies hondurensis has flowers 30 to 34 cm long. The differences between this species and many other Selenicereus species are said to be of degree rather than of kind, so those species would be reduced to synonyms of its subspecies.
Cultivation
S. grandiflorus is a fast-growing plant. It is kept on the dry side each winter and moved outdoors under a shade tree in late spring. It needs compost containing plenty of humus and sufficient moisture in summer. It performs best in full sun, and extra light in early spring stimulates budding.
The genus Selenicereus
Selenicereus is a genus of epiphytic, lithophytic and terrestrial cacti, found in Mexico, Central America, the Caribbean and northern South America. It is sometimes known as moonlight cactus. The term night-blooming cereus is also used for many other night-blooming cacti, including Epiphyllum and Peniocereus. In 2017 the genus Hylocereus was brought into synonymy with Selenicereus, after a molecular phylogenetic study showed it nested within Selenicereus.
The receptacle of the genus bears small bracts, hairs and usually spines, and the fruits bear numerous spines. Selenicereus megalanthus has flowers 30 to 38 cm long and yellow fruit, while S. costaricensis has flowers about 30 cm long and red fruit with purple pulp. S. anthonyanus has flowers about 12 cm long and 10 to 15 cm wide, with purplish outer tepals and cream inner ones. S. stenopterus has flowers 9 to 10 cm long and 13 to 15 cm wide with purplish red tepals, and S. minutiflorus has white flowers 5 cm long and 8 to 9 cm wide. S. spinulosus grows in Texas and Mexico, and S. setaceus in Argentina, Bolivia, Brazil and Paraguay.
Night-blooming cereus as a group of cacti
Night-blooming cereus is a common name for many flowering ceroid cacti that bloom at night. Their flowers are almost always white or very pale shades of other colours, often large and frequently fragrant. Most open after nightfall and are wilting by dawn. Plants in the same area tend to bloom on the same night, and a healthy plant can bloom up to three times over the warmest months. Other names used for such cacti include princess of the night, Honolulu queen, Christ in the manger and dama de noche. The name is given to species of Cereus, Echinopsis, Epiphyllum, Harrisia, Hylocereus, Monvillea, Nyctocereus, Peniocereus, Selenicereus and Trichocereus.
Selenicereus undatus, formerly Hylocereus undatus, is the most cultivated species of the genus Selenicereus. It is grown both as an ornamental vine and as a fruit crop, the pitahaya or dragon fruit, and its scented nocturnal flowers are 25 to 30 cm long.
Scent of the flowers
The scent of nocturnal cactus flowers is tied to their pollinators. Bat-pollinated flowers usually produce sulphur-containing volatiles with a cabbage-like smell, whereas moth-pollinated species emit complex blends of terpenoids and benzenoids.
Epiphyllum oxypetalum, the Dutchman's pipe cactus, is the most popular cultivated night-blooming cereus, although it is not closely related to the species of the tribe Cereeae that more commonly bear the name. Its very fragrant flowers are up to 30 cm long and open for a single night. Scent emission starts after 8 p.m. local time and rises 200-fold within six hours. At full bloom geraniol makes up 72.54% of the emission, followed by benzyl alcohol at 12.96% and methyl salicylate at 3.75%. The scent begins with a mild phenolic odour before turning to a pronounced fragrance. Benzyl salicylate and methyl linoleate are also reported as the principal odour components of its aroma.
