It is not an easy task to capture floral diversity by floral diagrams. To be fully comprehensive, several volumes would have to be written, comprising several hundreds of drawings. However, characters on floral diagrams are clear enough to reflect where a taxon belongs and can be used for identification at least to family level. Floral diagrams are increasingly important as a principal means in understanding the complexity of flowers and leading to hitherto unexplored floral characters. While the phylogeny of angiosperms is being progressively refined by worldwide collaborative research (APG III will be published before this book will be out), the challenge for studying flowers and their hidden secrets becomes increasingly important. While writing this book, I made several new observations of flower structures by study of fresh flowers, while the information from the literature was either too basic, or restricted to obscure nineteenth-century work. While Eichler had broader access to a wide botanical knowledge, this knowledge has become progressively eroded during the twentieth century because of emphasis on new exciting areas of botany. Nowadays, we know much more about the genetic structure of plant groups than about their floral structure. The scope of morphological research is immense, especially in tropical families for which only a fraction of the diversity is currently known. In the present biodiversity crisis, such studies are a race against time, with the certainty that pertinent scientific knowledge and aesthetic models are lost forever, before even being discovered.