Type of FlowersChrismas Cactus:
Christmas Cactus "Schlumbergera" is a small genus of cacti with six species found in the coastal mountains of south-eastern Brazil. Plants grow on trees or rocks in habitats which 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 areoles at the joints and tips of the stems. Two species have cylindrical stems more similar to other cacti. In Brazil, the genus is referred to as Flor de Maio (May flower), reflecting the period in which they flower in the Southern Hemisphere.
This genus contains the popular house plants known by a variety of names including Christmas Cactus, Thanksgiving Cactus, Crab Cactus and Holiday Cactus, which are Schlumbergera cultivars, and flower in white, pink, yellow, orange, red or purple. (The Easter Cactus or Whitsun Cactus, which may also be called a Holiday Cactus and has vivid scarlet flowers in the most commonly grown form, is now placed in the genus Hatiora.)
The cultivars of Christmas Cactus"Schlumbergera" 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 symmetical 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.
Christmas Cactus "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 now called S. × buckleyi, first recorded in 1852. By the 1860s, a substantial number of cultivars (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.
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 mutations 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). 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.