The genus Schlumbergera was established by Lemaire in 1858 for the Brazilian epiphyte Epiphyllum russellianum Hook. (Schlumbergera epiphylloides Lem., nom. illegit.). A second species, S. gaertneri (E. russellianum var. gaertneri Regel), also native to Brazil, was added in 1913 by Britton & Rose, and a third S. bridgesii (Epiphyllum bridgesii Lem.) of unknown origin and dubious identity, by Loefgren in 1918. A fourth, more recent, addition has been S. truncata (Haw.) Moran (E. truncatum Haw.). Vaupel (1925, 1926) united Schlumbergera (excluding S. gaertneri, which he transferred to Rhipsalis), with Zygocactus K. Schum. (1890) and Epiphyllanthus A. Berger (1905), under Epiphyllum sensu Pfeiff. non Haw. Following Pfeiffer (1837), it had become the European tradition to reject Epiphyllum Haw. (1812) in favour of Phyllocactus Link (1831), both names based on Cactus phyllanthus L., for the epiphytic cacti with large or relatively large regular flowers. The name Epiphyllum sensu Pfeiff. was retained for the irregularflowered E. truncatum Haw. (1819) and E. altensteinii Pfeiff., later considered to be synonymous. This long-standing error of usage, pointed out and corrected byBritton & Rose (1913), after being allowed to stand by Schumann (1897-9) (although he had previously placed E. truncatum in a new genus Zygocactus (1890) ), was perpetuated by Vaupel. An attempt to conserve Phyllocactus (Werdermann, 1937) failed, and under modern rules both this name and Epiphyllum Pfeiff. are illegitimate. The oldest legitimate name for Epiphyllum sensu Vaupel is Schlumbergera Lem. From the time of Britton & Rose's monograph (1923), it has been more customary among writers on the Cactaceae to maintain Schlumbergera, Zygocactus and Epiphyllanthus as separate genera. Britton & Rose made little use of infrageneric (and, for that matter, infraspecific) categories and their wholesale splitting of genera, not only in the Cactaceae, represents, in the words of one of their countrymen, 'nearly the height of a local "liberalism" endemic in the United States in the period from about 1900oo to 1930' (Benson, 1940). Liberalism, nevertheless, has been the order of the day among students of the Cactaceae since Britton & Rose, culminating in the recognition of no fewer than 233 genera by Backeberg (1959-62, 1966). In the group of species with which we are concerned here, only Loefgren (I918) and Moran (1953), apart from Vaupel, have adopted a broader generic concept than the American monographers. Neither Loefgren nor Moran went as far as Vaupel, however, and their views should not be passed over without comment.