Dorothy is packing up to head back to school tomorrow and one thing she has to take back with her is a small box with a half dozen plants, including two Thanksgiving cacti. Thanksgiving and Christmas cacti are similar and related, both being cultivars of plants in the genus Schlumbergera. Christmas cactus are Schlumbergera x buckleyi, a hybrid between S. truncata and S. russelliana, while Thanksgiving cactus are S. truncata. There are a few distinguishing features of the Thanksgiving cactus, besides the earlier bloom date. The stem segments (those are stems, not leaves) have pointed teeth, their flowers are not symmetrical (the top is different to the bottom, the technical term being zygomorphic), and they have yellow pollen. The Christmas cactus has rounded stem segments, symmetrical flowers, and pink pollen. They are both native to the Organ Mountain range north of Rio de Janeiro in Brazil.