This current book is a development of ideas put forward in the four published editions of The Identification of Flowering Plant Families (1965, 1979, 1989, 1997). The modest success of this book, and its persistence in print for such a long period, has led me to rewrite it completely, taking account of relatively recent developments in the recognition of flowering plant families.

Plant taxonomy is a free and unregulated subject, open to contributions from researchers and students of all kinds; because of this a vast range of opinions co-exist at any one time and to the casual observer the situation may appear chaotic. However, at any time there is a general, unregulated and undefined consensus as to what the taxonomic system should be. This consensus, which is expressed in the use of the various levels of the taxonomic hierarchy in Floras, revisions and other studies involving taxonomic practice, slowly changes in response to new ideas. Over the past 15 years, new ideas of what the family level means have become current: present-day authors are happy to recognise more groups as families than was the case 40 years ago, when the first edition of The Identification … was published.

The aim of the book is to provide a means of accurate identification of the flowering plant families native in north temperate regions, and to indicate how to proceed to identification of the genera and species; the assumption is made that the user has a general knowledge of plant structure, but is otherwise not particularly expert at identification or taxonomy.