There are a number of different cactus species sold as "Christmas cactus," including Schlumbergera opuntioides, Schlumbergera kautskyi, and Schlumbergera microsphaerica.
As with many other species of the genus (see Schlumbergera: Taxonomy), other generic names were used afterwards: Zygocactus (Löfgren in 1918), Epiphyllanthus (Moran in 1953) and finally Schlumbergera (David Hunt in 1969).
Schlumbergera opuntioides | Schlumbergera microsphaerica | Schlumbergera kautskyi | Schlumbergera | ''Schlumbergera'': Taxonomy | Close-up of a ''Schlumbergera |