The Ranunculaceae is a moderately large family with 59 genera and ca. 2500 species. Many of these have beautiful flowers or substances with strong physiological activity. They are used as ornamental or medicinal plants. This family shows great diversity in both vegetative and reproductive structures as well as in ecology. It retains many primitive characters and is regarded as one of the most primitive angiospermous families, but on the other hand it often presents quite specialized or advanced features. Therefore the family has attracted attention of many botanists from various points of view, and its members have been studied not only taxonomically, but also morphologically, anatomically, embryologically, palynologically, cytologically, phytochemically, serologically, and so on. Thus the Ranunculaceae are indeed an intensively studied family. The main author of this book, M. Tamura has been studying the family taxonomically for more than 40 years.

In the history of the taxonomic studies of the Ranunculaceae, there were three monumental works. The first is that of A. P. De Candolle. In the first volume of his "Systema Naturale" (1817) the family has been monographed at the species level for the first time. His work was excellent and gave a sound base to the taxonomy of the family and influenced the subsequent work for a long time. The second monograph at the generic level is that of K. Prantl (1888) which appeared in "Die natürlichen Pflanzenfamilien". This author used anatomical and embryological characters, in addition to traditional morphological ones for the classification of the family, and tried to make a phylogenetic system. The third work is of O. F. I. Langlet (1932) based on karyology. He noticed the importance of karyological features in the taxonomy of the Ranunculaceae and defined the phyletic groups mainly by such characters. His work is one of the most successful examples of cytotaxonomy established in those days. The classification presented here is an extension of the work of these three.

The treatment of Ranunculaceae presented in this volume of "Die natürlichen Pflanzenfamilien" is the most comprehensive and the most detailed one until now, especially with regard to the infrageneric taxonomy.