The term “Christmas Cactus” describes a popular group of houseplants that bloom during the winter season, but this common name often causes confusion. The plants commonly sold during the holiday season are actually three distinct types: the Thanksgiving, Christmas, and Easter cacti. Understanding the differences in their physical structure, scientific classification, and natural bloom cycles is the most effective way to correctly identify each variety.
The Three Common Holiday Cactus Types
Most holiday cacti found in stores belong to the genus Schlumbergera, which includes the Thanksgiving Cactus and the true Christmas Cactus. The Thanksgiving Cactus, Schlumbergera truncata, is the most widely cultivated and sold variety during the holiday season because it is easier to propagate commercially. It is frequently mislabeled as the Christmas Cactus.
The true Christmas Cactus, Schlumbergera x buckleyi, is a hybrid resulting from a cross between S. truncata and S. russelliana. This hybrid is less common in commercial markets today. Both Schlumbergera types are native to the coastal mountains of southeastern Brazil, where they grow as epiphytes on trees or rocks in humid, shady rainforest environments.
The third type, the Easter Cactus, belongs to a different genus, typically Hatiora or Rhipsalidopsis. This species, often classified as Hatiora gaertneri, is genetically distinct from the Schlumbergera species. This difference is reflected in its unique physical characteristics and its much later natural bloom period in the spring.
Distinguishing Physical Characteristics
The most reliable way to differentiate these plants is by examining the shape of their flattened stem segments, known as phylloclades. The Thanksgiving Cactus (S. truncata) has segments with two to four distinct, pointed, or claw-like teeth along the margins, earning it the common nickname “Crab Cactus.” This sharp, serrated edge is a key identifier.
In contrast, the true Christmas Cactus (S. x buckleyi) has segments with more rounded, symmetrical, and scalloped edges that lack the sharp points of the Thanksgiving variety. The Easter Cactus (Hatiora gaertneri) has segments that are even more rounded and oval-shaped, often featuring subtle hairs, or bristles, at the tips of the segments.
The flowers themselves also exhibit clear differences in shape and orientation. The Thanksgiving Cactus produces flowers that are bilaterally symmetrical (zygomorphic) and held horizontally, or slightly upward, from the stem ends. The true Christmas Cactus flowers are generally more regular and tend to hang downward in a pendulous fashion. The Easter Cactus flowers are distinctively star-shaped and radially symmetrical, with thinner petals, which contrasts sharply with the tubular blooms of the Schlumbergera species.
Understanding Bloom Timing and Origin
The common names of these cacti directly correlate with their natural bloom times in the Northern Hemisphere. These bloom times are triggered by changes in photoperiod and temperature. Unlike desert cacti, these plants need cooler temperatures and long periods of uninterrupted darkness to set their flower buds.
The Thanksgiving Cactus typically blooms first, starting in late fall around November, because it responds earlier to the shortening days and cooler temperatures. The true Christmas Cactus usually follows a few weeks later, with its natural blooming period generally occurring from late December into January. Both Schlumbergera species require approximately 12 to 14 hours of continuous darkness per night, coupled with cool nighttime temperatures, typically between 50 and 60 degrees Fahrenheit, to encourage bud formation.
The Easter Cactus has the longest dormancy period between blooms and is a “long-day” plant, with flowering naturally occurring in the spring, from March through May. Its bloom cycle is triggered by a combination of increasing day length and a specific cool-temperature requirement during the winter rest period. This difference in timing explains why the Thanksgiving Cactus is the most prevalent variety sold commercially, as its earlier response to environmental controls allows growers to consistently time its bloom for the peak winter holiday season.