(hybrid Schlumbergera × buckleyi), popular cactus of the family Cactaceae that has flattened stems and is grown for its colourful cerise flowers that bloom indoors about Christmastime in the Northern Hemisphere. Most Christmas cacti now in cultivation are considered to be hybrids of the crab cactus (S. truncata) and S. russelliana. Like other Schlumbergera species, it is native to Brazil, and it grows in the rainforest, perched on trees or shrubs as epiphytes or sometimes in shady places among rocks. The alternative genus name, Zygocactus, is frequently encountered.