From the preface:
""A Time of Change" would be a suitable heading to describe the present state of Crassulaceae systematics. The first steps to review and prepare a ‘consensus classification’ of the Crassulaceae some 50 years after the publication of the last monographic treatment of this family were taken several years back. This initiative culminated in a round-table discussion at the 1992 Congress of the "International Organization for Succulent Plant Study, IOS" in Phoenix. It is a great pleasure to report now that the original initiative has resulted in much more than a mere ‘consensus classification’ or ‘umbrella’ for diverging classificatory views. The papers presented during the symposium "Evolution and Systematics of the Crassulaceae" during the 23rd Congress of IOS in Wageningen on August 20th 1994, which are united in this volume, show that significant advances have been made in Crassulaceae systematics in recent years – by ‘modern’ methods and ‘traditional’ techniques alike – and we are very grateful to all the participating colleagues for sharing their knowledge. While the ‘definite’ classification of the family (if such exists) is still a distant goal, the following contributions show a broad agreement in basic concepts and this general mutual understanding provides a firm base for subsequent (and still much-needed) work to improve the ideas now presented."