BOOKS AND CURRENT LITERATURE 



Monograph of the Cactaceae. — For seven years Britton and Rose 

 have been engaged in the preparation of a monograph of the Cactaceae, 

 which is destined to supersede Schumann's Gesamtbeschreibung der 

 Kakteen as the authoritative treatment of this family. Through the 

 aid of the Carnegie Institution it has been possible to explore the cactus 

 regions of South America, as well as to examine types in European 

 herbaria and to maintain living collections for study. The inadequacy 

 of herbarium material in representing the characters of cacti and the 

 large number of names based on incomplete descriptions of living plants 

 has made the task of the authors a very dificult one. It is planned to 

 issue the monograph in four volumes, the first of which has just ap- 

 peared, 1 covering Pereskia, Opuntia and related genera. The genus 

 Opuntia is the largest of the family, containing 254 species, and has been 

 divided into three sub-genera, Cylindropuntia, Tephrocactus and Pla- 

 tyopuntia, containing respectively 13, 4 and 29 series. Of these series 

 31 have representatives in North America and 15 are confined to South 

 America. Keys, descriptions, bibliographical references, and citations 

 to illustrations are given, and nearly every species is illustrated by col- 

 ored plate, half tone or line cut. The volume has been published in 

 most sumptuous form, but it leaves the reader with regret that the an- 

 cient practise of illuminating monographs with colored plates, whose 

 cost is out of all proportion to their value, has persisted to this late 

 and practical day. 



From the systematic standpoint the work is notable for the fresh 

 grouping of the species in this large genus, for the elucidation of the 

 poorly known South American species, and for the conservatism with 

 which the North American forms have been treated. Under Opuntia 

 opuntia, for example, 21 specific and varietal names have been reduced to 

 synonomy, under 0. engelmannii 11 names, and under 0. lindheimeri 20 

 names. In many cases the relegation of names to synonomy has been 

 due to inadequacy of the type material, uncertainty as to the exact 



britton, N. L. and Rose, J. N. The Cactaceae; descriptions and illustra- 

 tions of plants of the cactus family. Vol. I. Carnegie Inst. Wash. Publ. 248. 

 Pp. 236, pis. 36, text figs. 302. 1919. 



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