These same conditions are needed by the earlier blooming Thanksgiving cactus (Schlumbergera truncata) and there is a strong family resemblance between the cousins.

A. Christmas cactuses (Schlumbergera truncata), now available in bloom at many florists and dime stores, are epiphytic, or tree-perching, members of the cactus family.

Following Ludwig Pfeiffer in 1837, the European tradition was to use Phyllocactus for epiphytic cacti with large regular flowers and Epiphyllum for the irregular-flowered species now called Schlumbergera truncata.

- Florence Shedroff, Bayside, Queens A. The dangling, tubular flowers of the Christmas or crab cactus (Schlumbergera truncata) begin as buds that are set in autumn for a blooming period around Christmas.