''Rhipsalidopsis gaertneri'',

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

''Schlumbergera gaertneri'' and ''Hatiora gaertneri'', is a species of epiphytic cactus which belongs to the tribe Rhipsalideae within the subfamily Cactoideae of the Cactaceae. Together with the hybrid with '' R. rosea'', ''Rhipsalidopsis'' × ''graeseri'', it is known, in English speaking countries in the Northern Hemisphere, as Easter cactus or Whitsun cactus and is a widely cultivated ornamental plant. It has received the Royal Horticultural Society's

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The Award of Garden Merit ...

Description

''Rhipsalidopsis gaertneri'' is found in southeastern Brazil, in Paraná and Santa Catarina, at altitudes of . ''R. gaertneri'' grows on trees ( epiphytic) or less often rocks ( lithophytic) in sub-tropical rain forest. With maturity, it develops into a branching pendant leafless shrub with a woody base. The stems are made up of segments, most of which are flattened and which are the

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

organs ( cladodes) of the plant. Younger segments are dullish green, long and wide, with small notches on the margins. Structures characteristic of cacti, called areoles, form in these notches. Flowers form from areoles at the ends of the stems. These are scarlet in colour, long, radially symmetrical (actinomorphic), opening to a funnel shape with a maximum diameter of about . Red oblong fruits form after the flowers are fertilized.

Taxonomy

Although cacti belonging to the tribe Rhipsalideae are quite distinct in appearance and habit from other cacti, as they grow on trees or rocks as epiphytes or lithophytes, for a long time there has been confusion as to how the species should be placed into genera. ''Rhipsalidopsis gaertneri'' was first described in 1884 by Eduard von Regel as the variety ''gaertneri'' of ''Epiphyllum russellianum'' (now '' Schlumbergera russelliana''). The name honours one of the Gaertner family, early settlers in Blumenau, Brazil.Arquivo Histórico José Ferreira da Silva

/ref> The species has had a complex taxonomic history. In 1889, William Watson (19th century botanist), William Watson elevated it to the full species ''Epiphyllum gaertneri'' and in 1913,

Nathaniel Britton Nathaniel Lord Britton (January 15, 1859 – June 25, 1934) was an American botanist and taxonomist who co-founded the New York Botanical Garden in the Bronx, New York. Early life Britton was born in New Dorp in Staten Island, New York to Jasper ...

and Josephy Rose transferred it to ''

Schlumbergera ''Schlumbergera'' is a small genus of cacti with six to nine species found in the coastal mountains of south-eastern Brazil. These plants grow on trees or rocks in habitats that are generally shady with high humidity, and can be quite differen ...

'' as ''S. gaertneri''. The relationship to ''S. russelliana'' was based on the appearance of the stems, made up of somewhat flattened segments with small teeth, and the radially symmetrical shape of the flowers. However, the deeper structure of the flower differs from ''Schlumbergera'' species, which have a short floral tube at the base of the flower formed by fused petals, and stamens arranged in two distinct series, whereas ''Rhipsalidopsis gaertneri'' has separate petals and a single series of stamens. ''Rh. gaertneri'' was separated from ''Schlumbergera'' as ''Rhipsalis gaertneri'' by Friedrich Vaupel in 1925, after which it was successively transferred to ''Epiphyllopsis'' by

Alwin Berger Alwin Berger (28 August 1871 – 20 April 1931) was a German botanist best known for his contribution to the nomenclature of succulent plants, particularly agaves and cacti. Born in Germany he worked at the botanical gardens in Dresden and Fran ...

in 1929, ''Rhipsalidopsis'' by

Karl Hermann Leonhard Lindinger Karl may refer to: People * Karl (given name), including a list of people and characters with the name * Karl der Große, commonly known in English as Charlemagne * Karl Marx, German philosopher and political writer * Karl of Austria, last Austria ...

in 1942, and ''Hatiora'' by Wilhelm Barthlott in 1987. It was put back in ''Schlumbergera'' as the result of

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies in 2011, and then restored to ''Rhipsalidopsis'' again. In horticultural sources, the Easter cactus continued to be referred to as ''Schlumbergera gaertneri'' (even when other sources placed it in ''Hatiora''), as well as ''Rhipsalidopsis gaertneri''.

Cultivation

Under the name Easter cactus or Whitsun cactus, ''Rhipsalidopsis gaertneri'' is widely cultivated as an ornamental plant for its scarlet flowers. Its common names reflect the period in which it flowers in the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

, namely late Spring. It has been artificially crossed with a pink-flowered species, '' Rhipsalidopsis rosea'', to form the hybrid ''Rhipsalidopsis'' × ''graeseri'', cultivars of which have flowers in a wider range of colours. The Easter cactus is considered more difficult to grow than the Christmas or Thanksgiving cactus (cultivars and hybrids of ''

''). Recommendations for care include: * ''Temperature'' Summer temperatures around are suggested, with lower temperatures down to in the winter (November to January in the Northern Hemisphere) to initiate good bud formation. * ''Light'' As epiphytic forest plants, they are not exposed to strong sunlight. Half-shade is recommended; plants can be placed outside in the summer., p. 74 * ''Watering'' The Easter cactus is said to respond badly to over- or under-watering, e.g. by losing stem segments; continuously moist soil is recommended. * ''Propagation'' Stem segments may be removed in late Spring and the cut surface allowed to dry out before being placed in slightly moist soil.

References

Bibliography

* {{Taxonbar, from1=Q3153249, from2=Q138282 Rhipsalideae Cacti of South America Endemic flora of Brazil Flora of the Atlantic Forest Flora of Paraná (state) Flora of Santa Catarina (state) Plants described in 1884 Epiphytes Garden plants of South America