''Schlumbergera'' is a small
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
cacti with six to nine species found in the coastal mountains of south-eastern
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
. These plants grow on trees or rocks in habitats that are generally shady with high humidity, and can be quite different in appearance from their
desert-dwelling cousins. Most species of ''Schlumbergera'' have stems which resemble leaf-like pads joined one to the other and flowers which appear from
areole
In botany, areoles are small light- to dark-colored bumps on cacti out of which grow clusters of spines. Areoles are important diagnostic features of cacti, and identify them as a family distinct from other succulent plants. Gordon Rowley - W ...
s at the joints and tips of the stems. Two species have cylindrical stems more similar to other cacti. Recent
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
studies using
DNA have led to three species of the related genus ''
Hatiora'' being transferred into ''Schlumbergera,''
[ though this change is not universally accepted.
Common names for these cacti generally refer to their flowering season. In the Northern Hemisphere, they are called Christmas cactus, Thanksgiving cactus, crab cactus and holiday cactus. In Brazil, the genus is referred to as (May flower), reflecting the period in which they flower in the Southern Hemisphere. Most of the popular houseplants are ]cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s of ''Schlumbergera'', rather than species, with flowers in white, pink, yellow, orange, red or purple. The Easter cactus or Whitsun cactus, until recently placed in the genus '' Hatiora'', is also called a holiday cactus and has flowers in red, orange, pink and white.
The cultivars of the Christmas cactus fall into two main groups:
* The Truncata Group contains all cultivars with features derived mainly from the species '' S. truncata:'' stem segments with pointed teeth; flowers held more or less horizontally, usually above the horizontal, whose upper side is differently shaped from the lower side (zygomorphic); and pollen which is yellow. They generally flower earlier than members of the Buckleyi Group and, although common names are not applied consistently, may be distinguished as Thanksgiving cactus, crab cactus or claw cactus.
* The Buckleyi Group contains all cultivars with at least some features clearly showing inheritance from '' S. russelliana:'' stem segments with rounded, more symmetrical teeth; more or less symmetrical (regular) flowers which hang down, below the horizontal; and pollen which is pink. They generally flower later than members of the Truncata Group and are more likely to be called Christmas cactus.
Description
In the wild, the species of ''Schlumbergera'' grow either on trees (epiphytic
An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...
) or on rocks ( epilithic) and can form sizeable shrubs with woody bases; a height of up to has been reported for one species (''S. opuntioides''). They are leafless, the green stems acting as photosynthetic organs. The stems are composed of segments, which take one of two forms. In most species the segments are strongly flattened (cladode
Phylloclades and cladodes are flattened, photosynthetic shoots, which are usually considered to be modified branches. The two terms are used either differently or interchangeably by different authors. '' Phyllocladus'', a genus of conifer, is nam ...
s), being made up of a central core with two (or more rarely three) "wings". Special structures characteristic of cacti, called "areole
In botany, areoles are small light- to dark-colored bumps on cacti out of which grow clusters of spines. Areoles are important diagnostic features of cacti, and identify them as a family distinct from other succulent plants. Gordon Rowley - W ...
s", then occur at the ends of the segments of the stem. In two species the stems are less flattened, more cylinder-shaped, and the areoles are arranged in a more or less spiral pattern all over the segments. In both cases, the areoles, which may have wool and bristles, are where the flower buds appear.[, particularly pp. 18–19]
The flowers either hang downwards and are almost regular (radially symmetrical or actinomorphic
Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts.
Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...
) or, as in most species, are held more or less horizontally with the higher side of the flower different from the lower side (radially asymmetrical or zygomorphic
Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts.
Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...
). In those species whose flowers are held up, their angle with the horizontal is relatively constant and is characteristic of the species. Each flower has 20–30 tepal
A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...
s. The outer tepals – those closer to the base of the flower – are short and unconnected, and spread out or curve backwards. The inner tepals – those towards the tip of the flower – are longer and in most species become progressively more fused together at the base to form a floral tube. In some species the difference between the outer and inner tepals creates the appearance of a "flower within a flower". The flowers produce nectar in a chamber at the base of the floral tube.[
In most species, the many stamens are arranged in two series, with the inner stamens being fused at the base to form a short tubular structure and the outer stamens arising from along the floral tube. The ]style
Style is a manner of doing or presenting things and may refer to:
* Architectural style, the features that make a building or structure historically identifiable
* Design, the process of creating something
* Fashion, a prevailing mode of clothing ...
is usually dark red and has a stigma with 6–8 lobes; the style plus stigma is roughly the same length as the stamens. If the flower is fertilized
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...
, a fleshy fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
forms, either smooth or with ribs. The brown or black seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s are about 1 mm in diameter.[
]
Taxonomy
The 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 ...
is one of a small number belonging to a group of cacti classified as the tribe Rhipsalideae
The Rhipsalideae are a small tribe of cacti, comprising four genera (and around 60 species). They grow on trees (epiphytes) or on rocks ( lithophytes), where they either hang down or form creeping or upright shrubs. Their flowers open in the day ...
. Species of cacti belonging to this group are quite distinct in appearance and habit from most other cacti since they grow on trees or rocks as epiphytes or lithophyte
Lithophytes are plants that grow in or on rocks. They can be classified as either epilithic (or epipetric) or endolithic; epilithic lithophytes grow on the surfaces of rocks, while endolithic lithophytes grow in the crevices of rocks (and are als ...
s. Although the species are easy to identify as members of the Rhipsalideae, for many years there was confusion as to how they should be divided into genera. This confusion extended to ''Schlumbergera'', whose complicated taxonomic history has been detailed by McMillan and Horobin. The modern genus ''Schlumbergera'' was created by Charles Lemaire
Charles LeMaire (April 22, 1897 – June 8, 1985) was an American costume designer. He
was born in Chicago.
LeMaire's early career was as a vaudeville performer, but he became a costume designer for such Broadway productions as '' Ziegfeld Fo ...
in 1858. The name commemorates Frédéric Schlumberger, who had a collection of cacti at his chateau near Rouen. Lemaire placed only one species in his new genus – a plant discovered in Brazil in 1837 which had been named ''Epiphyllum russellianum'' by William J. Hooker. Lemaire renamed it ''Schlumbergera epiphylloides'' (under the current rules of botanical nomenclature it should have been called ''Schlumbergera russelliana'', which is its current name).[
Lemaire noted the similarity of his ''Schlumbergera epiphylloides'' to a species first described as ''Epiphyllum truncatum'' by ]Adrian Hardy Haworth
Adrian is a form of the Latin given name Adrianus or Hadrianus. Its ultimate origin is most likely via the former river Adria from the Venetic and Illyrian word ''adur'', meaning "sea" or "water".
The Adria was until the 8th century BC the mai ...
in 1819, but did not accept that the two species should be included in the same genus. In 1890, Karl Moritz Schumann
Karl Moritz Schumann (17 June 1851 – 22 March 1904) was a German botanist.
Schumann was born in Görlitz. He was curator of the Botanisches Museum in Berlin-Dahlem from 1880 until 1894. He also served as the first chairman of the ''Deutsc ...
created the new genus ''Zygocactus'',[ transferring ''Epiphyllum truncatum'' to ''Zygocactus truncatus''. Although he later placed it back in ''Epiphyllum'', abandoning ''Zygocactus'', the generic name ''Zygocactus'' continued to be widely used.][
In 1913, Nathaniel Britton and Joseph Rose followed Lemaire in keeping ''Schlumbergera russelliana'' and ''Zygocactus truncatus'' in separate genera. They also transferred the Easter cactus to ''Schlumbergera'' as ''S. gaertneri'', initiating a lasting confusion between these two genera.][
In 1953, ]Reid Venable Moran
Reid Venable Moran (June 30, 1916 – January 21, 2010) was an American botanist and the curator of botany at the San Diego Natural History Museum from 1957 to 1982.
Moran was the world authority on the Crassulaceae, a family of succulent plant ...
placed both ''Schlumbergera russelliana'' and ''Zygocactus truncatus'' in the genus ''Schlumbergera''. Other species were added later by David Hunt, including those formerly placed in ''Epiphyllanthus'', to form the modern total of six full species and a number of hybrids.[
''Schlumbergera'' and ''Hatiora'' have long been confused. Species in the former genus generally have flowers that are zygomorphic with a distinct floral tube, while those in the latter have actinomorphic flowers with inconspicuous tubes. DNA data shows that as previously circumscribed the two genera are not monophyletic and the three species in ''Hatiora'' subgenus ''Rhipsalidopsis'' have been transferred into ''Schlumbergera'',] although this change has not been universally adopted.
Synonymy
The following genera are now synonyms of ''Schlumbergera'' (i.e. they have no species not moved into ''Schlumbergera''):[
* ''Epiphyllanthus'' A.Berger
* ''Opuntiopsis'' Knebel (nom. inval.)
* ''Zygocactus'' ]K.Schum.
Karl Moritz Schumann (17 June 1851 – 22 March 1904) was a German botanist.
Schumann was born in Görlitz. He was curator of the Botanisches Museum in Berlin-Dahlem from 1880 until 1894. He also served as the first chairman of the ''Deut ...
* ''Zygocereus'' Frič & Kreuz. (orth. var.)
* ''Epiphyllum'' Pfeiff. but not ''Epiphyllum'' Haw.
The case of ''Epiphyllum'' is complex. In 1753, Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...
created the genus ''Cactus''. As more species were discovered this proved too broad, and new genera were set up to subdivide the cacti. The genus ''Epiphyllum'' was created in 1812 by Haworth, based on Linnaeus's ''Cactus phyllanthus''. In 1831, Johann Link created the genus ''Phyllocactus'' based on the same species. Following Ludwig Pfeiffer
K. Ludwig Pfeiffer is a German scholar in literary, media and cultural studies, born on February 23, 1944, in Neustadt an der Aisch, Middle Franconia, Germany. Besides his own publications, he is the editor and co-editor of 14 volumes in various r ...
in 1837, the European tradition was to use ''Phyllocactus'' for epiphytic cacti with large regular flowers and ''Epiphyllum'' for the irregular-flowered species now called ''Schlumbergera truncata''. Under modern rules, ''Phyllocactus'' is an illegitimate name, as is ''Epiphyllum'' in the sense of Pfeiffer; thus ''Epiphyllum'' Pfeiff. is a synonym of ''Schlumbergera''.[ The true genus '']Epiphyllum
''Epiphyllum'' (; "upon the leaf" in Greek) is a genus of epiphytic plants in the cactus family (Cactaceae), native to Central America and South America. Common names for these species include climbing cacti, orchid cacti and leaf cacti, though ...
'' Haw. now has around 19 species.[
]
Species
Between six and nine species are currently recognized. In the narrowest circumscription
Circumscription may refer to:
*Circumscribed circle
* Circumscription (logic)
*Circumscription (taxonomy)
*Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthrop ...
, ''Schlumbergera'' sensu stricto, six species are accepted. Only synonyms which have been widely used (and their basionyms) are given in the list below.
* ''Schlumbergera kautskyi
''Schlumbergera kautskyi'' is a species of plant in the family Cactaceae. It is Endemism, endemic to a small area of the coastal mountains of south-eastern Brazil where its natural habitat is rocky areas. It is threatened by habitat loss. It is i ...
'' (Horobin & McMillan) N.P.Taylor
: syn. ''S. truncata'' subsp. ''kautskyi'' Horobin & McMillan
* ''Schlumbergera microsphaerica
''Schlumbergera microsphaerica'' is a species of plant in the family Cactaceae. It is Endemism, endemic to a limited area of the coastal mountains of south-eastern Brazil where its natural habitat is rocky areas above . It is threatened by habita ...
'' (K.Schum.) Hoevel
*: syn. ''Cereus microsphaerica'' K.Schum., ''Epiphyllanthus microsphaericus'' (K.Schum.) Britton & Rose, ''Cereus obtusangulus'' K.Schum., ''Epiphyllanthus obtusangulus'' (K.Schum.) A.Berger, ''Zygocactus obtusangulus'' (K.Schum.) Loefgr., ''S. obtusangula'' (K.Schum.) D.R.Hunt
* '' Schlumbergera opuntioides'' (Loefgr. & Dusén) D.R.Hunt
*: syn. ''Epiphyllum opuntioides'' Loefgr. & Dusén, ''Zygocactus opuntioides'' (Loefgr. & Dusén) Loefgr., ''Epiphyllanthus opuntioides'' (Loefgr. & Dusén) Moran
* ''Schlumbergera orssichiana
''Schlumbergera orssichiana'' is a species of plant in the family Cactaceae. It is endemic to a small area of the coastal mountains of south-eastern Brazil where its natural habitat is moist forest. It grows on trees as an epiphyte. It is in the ...
'' Barthlott & McMillan
* ''Schlumbergera russelliana
''Schlumbergera russelliana'' is a species of plant in the family Cactaceae. It is endemic to a small area of the coastal mountains of south-eastern Brazil where its natural habitat is moist forest. It grows on trees as an epiphyte. It is one of ...
'' (Hook.) Britton & Rose
*: syn. ''Epiphyllum russellianum'' Hook., ''S. epiphylloides'' Lemaire, nom. illeg.
* ''Schlumbergera truncata
''Schlumbergera truncata'', the false Christmas cactus, is a species of plant in the family Cactaceae. It is endemic to a small area of the coastal mountains of south-eastern Brazil where its natural habitats are subtropical or tropical moist fo ...
'' (Haw.) Moran
*: syn. ''Epiphyllum truncatum'' Haw., ''Zygocactus truncatus'' (Haw.) K.Schum., nom. illeg.
In the widest circumscription, ''Schlumbergera'' sensu lato
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
, three species formerly placed in ''Hatiora'' are transferred into ''Schlumbergera''.[
* '' Schlumbergera gaertneri'' (Regel) Britton & Rose (Easter cactus, Whitsun cactus)
*: syn. ''Hatiora gaertneri'' (Regel) Barthlott, ''Rhipsalidopsis gaertneri'' (K.Schum.) Linding.
* '' Schlumbergera lutea'' Calvente & Zappi
*: syn. ''Hatiora epiphylloides'' (Porto & Werderm.) P.V.Heath
* '' Schlumbergera rosea''
*: syn. ''Hatiora rosea'' (Lagerh.) Barthlott, ''Rhipsalidopsis rosea'' (Lagerh.) Britton & Rose
Four hybrids of ''Schlumbergera'' s.s. have been named, all made in cultivation (although the first may possibly occur in the wild).] The ''International Code of Nomenclature for Cultivated Plants
The ''International Code of Nomenclature for Cultivated Plants'' (ICNCP), is a guide to the rules and regulations for naming cultigens, plants whose origin or selection is primarily due to intentional human activity. It is also known as Cultivat ...
'' recommends that cultivated plants should be named under its rules, not those appropriate for natural species and hybrids. The Group names given below were provided by McMillan and Horobin.
* ''Schlumbergera'' × ''buckleyi'' (T.Moore) Tjaden = ''S. russelliana'' × ''S. truncata''; ''S.'' Buckleyi Group
*: syn. ''Epiphyllum buckleyi'' T.Moore, ''E. rollissonii'' T.Moore, ''S. bridgesii'' (Lemaire) Loefgr.
* ''Schlumbergera'' × ''eprica'' Süpplie = ''S. orssichiana'' × ''S. russelliana'' [
* ''Schlumbergera'' × ''exotica'' Barthlott & Rauh = ''S. truncata'' × ''S. opuntioides''; ''S.'' Exotica Group
* ''Schlumbergera'' × ''reginae'' McMillan = ''S. truncata'' × ''S. orssichiana''; ''S.'' Reginae Group
A further hybrid of ''Schlumbergera'' s.l. is cultivated.]
* ''Schlumbergera'' × ''graeseri'' (Barthlott ex D.R.Hunt) D.R.Hunt = ''S. gaertneri'' × ''S. rosea''
Distribution, habitat and ecology
''Schlumbergera'' occurs only in the coastal mountains of south-east Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
, in the states of São Paulo
São Paulo (, ; Portuguese for ' Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the Ga ...
, Rio de Janeiro
Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a ...
, Minas Gerais
Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...
and Espírito Santo
Espírito Santo (, , ; ) is a state in southeastern Brazil. Its capital is Vitória, and its largest city is Serra. With an extensive coastline, the state hosts some of the country's main ports, and its beaches are significant tourist attra ...
. Sites where it has been found range from close to the Tropic of Capricorn
The Tropic of Capricorn (or the Southern Tropic) is the circle of latitude that contains the subsolar point at the December (or southern) solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reac ...
northwards to 20°S, i.e. in the southernmost part of the tropics.[ Plants grow at altitudes from in the case of ''S. truncata'' to in the case of ''S. microsphaerica'',] either in the coastal moist forests or in rocky areas. The natural distribution of ''Schlumbergera'' species has become confused because European cultivars were deliberately introduced into some areas, including the Serra dos Órgãos National Park
Serra dos Órgãos National Park ( pt, Parque Nacional da Serra dos Órgãos: "Organs Range") is a national park in the state of Rio de Janeiro, Brazil. It protects the Serra dos Órgãos mountain range and the water sources in the range. It wa ...
, by the Brazilian Agricultural Department, to compensate for over-collecting of wild plants.
Because of their height and proximity to the Atlantic Ocean, the coastal mountains produce high altitude moist forests – warm moist air is forced upwards into higher, colder locations where it condenses. ''Schlumbergera'' species grow in habitats which are generally relatively cool, shaded and of high humidity. David Hunt describes collecting specimens in conditions of cloud, drizzle and overnight temperatures down to .[ Plants are epiphytic or lithophytic, growing on moss-covered tree branches or in rock crevices, often in small pockets of substrate formed from decayed leaves and other vegetation. ''S. microsphaerica'' is found at higher altitudes, above ,][ in barren rocky habitats,][ and tolerates higher light levels.
The flowers of ''Schlumbergera'' have adaptations for pollination by hummingbirds: tubular flowers with abundant nectar, and colours towards the red end of the spectrum. Most species require ]cross-pollination
Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, bird ...
to set seed. The exceptions are ''S. kautskyi'' and ''S. microsphaerica''; as noted above, the latter is found at higher altitudes where hummingbirds may be absent or less common.
The fruits of ''Schlumbergera'' do not open spontaneously when ripe, and appear to be adapted for distribution by birds, which eat the seeds and pulp contained in the fruit. Birds have been observed removing seeds which had stuck to their beaks by rubbing them on tree branches, where the seeds might be able to germinate. Segments may also break off from the stems and take root, thus enabling plants to propagate vegetatively.
Cultivation of Christmas cacti
History
''Schlumbergera truncata'' was in cultivation in Europe by 1818, and ''S. russelliana'' was introduced in 1839. The two species were deliberately crossed in England by W. Buckley resulting in the hybrid
Hybrid may refer to:
Science
* Hybrid (biology), an offspring resulting from cross-breeding
** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species
** Hybridity, the property of a hybrid plant which is a union of two dif ...
now called ''S.'' × ''buckleyi'', first recorded in 1852. By the 1860s, a substantial number of cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s (cultivated varieties) were available in a range of colours and habits, and were used as ornamental plants in "stoves" (heated greenhouses) and in houses, where they were popular for their autumn and winter flowering. Many cultivars were selected seedlings of ''S. truncata'', but at least three ''S.'' × ''buckleyi'' hybrids were available, of which one, now called ''S.'' 'Buckleyi', is thought to be the original Christmas cactus. By the early part of the 20th century, the genus had become less popular, and many of the early cultivars were lost.[, particularly pp. 56–63]
From around the 1950s onwards, breeding resumed in Europe, North America, Australia and New Zealand. New plants were produced by crossing among the species and existing cultivars of ''S. truncata'', ''S. russelliana'' and the hybrid ''S.'' × ''buckleyi''. Treatments which induced mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA replication, DNA or viral repl ...
s were also used. The result was a wide range of flower colours which had not been available before, including the first true yellow to be sold commercially, ''S.'' 'Gold Charm' (which was a sterile triploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...
). Breeders aimed for plants which grew strongly, were upright at the point of sale rather than pendulous, had many flowers or buds, and were adapted to living as house plants.[
In the 1980s the species ''S. orssichiana'' was also used in crosses. The hybrid of ''S. truncata'' and ''S. orssichiana'' has been named ''S.'' × ''reginae'' or ''S.'' Reginae Group; one of the first cultivars was ''S.'' 'Bristol Queen'. ''S. opuntioides'' crosses have also been made, but have not resulted in commercially available cultivars.][
]
Modern cultivars
McMillan and Horobin have listed hundreds of modern European, North American and Australian cultivars of the Christmas cactus, which they put into a number of cultivar groups:[
* The Truncata Group contains all cultivars with mainly '' S. truncata'' characteristics: stem segments with pointed teeth (dentate); zygomorphic flowers held more or less horizontally, usually above the horizontal; and pollen which is yellow.
* The Buckleyi Group contains all cultivars with at least some features clearly showing inheritance from '' S. russelliana'': stem segments with rounded, more symmetrical teeth (crenate); more regular flowers which hang down, below the horizontal; and pollen which is pink. There is considerable variation within this Group; McMillan and Horobin introduced subcategories: "TB" for those more like ''S. truncata'' and "BT" for those more like the classic ''S.'' × ''buckleyi'', with "B" reserved for the first generation (F1) ''S.'' × ''buckleyi'' hybrids.
* The Reginae Group contains cultivars known to be derived from hybrids with '' S. orssichiana''.
* The Exotica Group is used for the small number of hybrids involving '' S. opuntioides''.
Attempts have also been made to classify cultivars by colour. A difficulty is that the flowers of many cultivars exhibit different colours depending on the temperature during bud formation and growth. In particular, temperatures below produce pink tones in otherwise white and yellow cultivars, and deepen the colour in pink and red cultivars. The availability of iron to the plant has also been suggested to affect flower colour.][
In the United States, cultivars are propagated in large numbers for sale before ]Thanksgiving Day
Thanksgiving is a national holiday celebrated on various dates in the United States, Canada, Grenada, Saint Lucia, Liberia, and unofficially in countries like Brazil and Philippines. It is also observed in the Netherlander town of Leiden and ...
(the fourth Thursday in November). In Europe, plants are mainly sold later in the year, in the period before Christmas
Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year ...
. A single Dutch grower (de Vries of Aalsmeer
Aalsmeer () is a municipality and a town in the Netherlands, in the province of North Holland. Its name is derived from the Dutch for eel (''aal'') and lake (''meer''). Aalsmeer is bordered by the Westeinderplassen lake, the largest open water of ...
, the Netherlands) was reported in 1989 as producing 2,000,000 plants per year.[
]
Common names
Plants are offered for sale under a variety of common names. The earliest English common name was "Christmas cactus". In Europe, where plants are largely produced for sale in the period before Christmas, this remains the most widely used common name in many languages for cultivars of all groups (e.g. in German,[ in French,][ and in Spanish][). This is also the name used in Canada.][ In the United States, where plants are produced for the Thanksgiving holiday in November, the name "Thanksgiving cactus" is used; "Christmas cactus" may then be restricted to cultivars of the Buckleyi Group,][ particularly the very old cultivars such as 'Buckleyi'.][ In Russia they are known as ''dekabrist'' ("decembrist") and ''rozhdestvennika'' ("nativity"). The name "crab cactus" (referring to the clawed ends of the stems) is also used for the Truncata Group.][ "Link cactus" is another common name, describing the way that the stems of the genus as a whole are made up of linked segments.][ The name "chain cactus" is common in New Zealand, and may also refer to '' Hatiora'' species.]
The Easter cactus or Whitsun cactus is now placed in the genus '' Hatiora'', but was at one time included in ''Schlumbergera'' (or one of its synonyms). The name "holiday cactus" has been used to include both ''Schlumbergera'' and ''Hatiora'' cultivars.[
]
Care of cultivars
When grown as house plants, ''Schlumbergera'' cultivars are said to be relatively easy to care for. McMillan and Horobin describe in detail their cultivation in both commercial and domestic conditions. Their specific recommendations include:
* ''Growing medium'': Free-draining, humus-rich, somewhat acid growing media are used for commercial production, such as a mixture of peat
Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficient ...
or leafmould and an inert material such as grit, sharp sand or polystyrene beads. It is recommended that plants should be grown in relatively small pots; half-height pots are suitable.
* ''Watering'': They are more tolerant of drought than many house plants, but can be damaged by both under- and over-watering. Keeping the growing medium just moist throughout the year avoids either extreme.
* ''Light'': They can be damaged by exposure to more than small amounts of sunlight. Members of the Buckleyi Group, such as the old-fashioned Christmas cactus with pendant flowers, are more tolerant of high light levels than members of the Truncata Group, such as most of the modern cultivars. Too much light causes stems to take on a reddish colouration; however, very low light levels will prevent flowering. Day length is important in controlling flowering; continuous darkness for at least 12 hours is necessary to induce bud formation. A period of about 8 days with 16 hours of darkness at has been shown to cause flower buds to form. Lower temperatures slow this process. The advice sometimes given to withhold water to produce flower buds has been shown to be incorrect.
* ''Propagation'': Both commercially and in the home, propagation can be achieved by using short pieces of stem, one to three segments long, twisted off rather than cut. Cuttings are allowed to dry for 1–7 days, forming a callus
A callus is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, but they may o ...
at the broken end, and then rooted in an open growing medium. Temperatures above and up to in long day/short night conditions speed rooting.
File:Schlumbergera IP.jpg, alt=A plant with green upright stems is growing in a blue pot. There are a few flowers and buds at the end of the stems, all more or less upright., Young plant of a member of the ''S.'' Truncata Group; still upright and therefore more convenient for selling
File:Schlumbergera growth.jpg, ''Schlumbergera'' new growth. The upper view shows bright red new cladodes forming, the centre shows maturing growth, the lower view shows two aerial root
Aerial roots are roots above the ground. They are almost always adventitious. They are found in diverse plant species, including epiphytes such as orchids (''Orchidaceae''), tropical coastal swamp trees such as mangroves, banyan figs (''Fic ...
s extending down
Pests and diseases
In cultivation, these plants have been described as "remarkably free from pests and diseases". Two significant insect pests are aphid
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...
s on young shoots, buds and flowers, and root mealybugs which attack below soil level. Stems and roots can be rotted by diseases caused by fungi and similar organisms; these include infections by species of ''Fusarium
''Fusarium'' is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil mi ...
'' (a fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...
), and ''Phytophthora
''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species are capable of causing enormous economic losses on crops worldwide, a ...
'' and ''Pythium
''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequen ...
'' (both water moulds). Approved chemical treatments can be used in the case of insect attack or these diseases.
Aphids, mealybugs and other invertebrate pests can spread virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsk ...
es. Symptoms vary with the species, but a loss of vigour is usual. Cactus virus X
Cactus virus X (CVX) is a plant pathogenic virus of the family ''Alphaflexiviridae
''Alphaflexiviridae'' is a family of viruses in the order ''Tymovirales
''Tymovirales'' is an order of viruses with five families. The group consists of virus ...
has been isolated from ''S. truncata''. There is no treatment for virus diseases; it is recommended that infected plants be destroyed.[
]
References
Bibliography
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External links
''Schlumbergera'' growing information
species, cultivar varieties, pictures and videos
Time-lapse video of ''Schlumbergera'' flower opening
{{Taxonbar, from=Q240857
Cacti of South America
Cactoideae genera
Christmas plants
Endemic flora of Brazil
Epiphytes
Flora of the Atlantic Forest
Garden plants of South America