The Cactaceae

The Cactaceae is a monograph on plants of the cactus family written by the American botanists Nathaniel Lord Britton and Joseph Nelson Rose and published in multiple volumes between 1919 and 1923. It was landmark study that extensively reorganized cactus taxonomy and is still considered a cornerstone of the field. It was illustrated with drawings and color plates principally by the British botanical artist Mary Emily Eaton as well as with black-and-white photographs.

Nathaniel Lord Britton was a Columbia University geology and biology professor who left the university in 1895 to become the founding director of the New York Botanical Garden. Much of his own field work was done in the Caribbean. Joseph Nelson Rose was an authority on several plant families, including parsley (Apiaceae) and cacti (Cactaceae). He had been a plant curator at the Smithsonian since 1896, and while working there he made several field trips to Mexico, collecting specimens for the Smithsonian and for Britton's newly founded New York Botanical Garden. Together, Britton and Rose published many articles on the stonecrop family (Crassulaceae) before embarking in 1904 on research leading towards The Cactaceae. With the support of Douglas T. MacDougal, director of the Carnegie Institution for Science's Desert Botanical Laboratory, the Carnegie Institution agreed to fund the project. Rose took a leave of absence from the Smithsonian to pursue it, and both Rose and Britton were named Carnegie Institution Research Associates in 1912, when more focused work on the project began. Between 1912 and 1916 Rose and Britton did extensive field work, collecting specimens and touring the botanical gardens and notable collections of Europe, the Caribbean, and North, Central, and South America.

In this period, cactus taxonomy was in a disorganized state with only a few very large and heterogeneous genera. Britton and Rose broke these old-style catch-all genera into smaller, more defined genera, ultimately classifying 1255 species under 124 genera. It has been argued that with this first major overhaul of cactus genera, they ushered in an era of 'splitting' or liberalism in cactus taxonomy, in contrast to the conservative 'lumping' approach that characterized their predecessors.

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