The genus Schlumbergera (Cactaceae) has several different vegetative forms. It is very variable and at least ten alleged forms of the type species, S. russelliana, have been collected and offered during the last 25 years, some of these are described and illustrated. Although naturally occurring intermediates or hybrids between S. russelliana and S. truncata in habitat have not been recorded, several of the forms discussed appear to the writer to be intermediates between these two species. Other intermediates are described and illustrated.