Genera Palmarum - The Evolution and Classification of the Palms

Abstract

• Since the publication of the first edition of Genera Palmarum in 1987, there has been an explosion of interest in this quintessentially tropical flowering plant family. Palms tend to attract attention, perhaps because of their recognisable rather simple growth form, their ecological and economic importance, or indeed simply because of their association with the exotic. The numerous biological intrigues within the family explain the abundance of palm research across the world, as demonstrated by the vast body of palm literature published since 1987 that is listed in the bibliography of this book. Genera Palmarum Edition 1 provided the basic taxonomic framework on which such palm studies could be based. Over the same period, worldwide interest in the cultivation of palms has also increased dramatically, and the range of species now available to the amateur grower is truly astonishing. In the past twenty years, there have been major advances in our understanding of the palm family. New exploration, particularly in Madagascar and the West Pacific, has uncovered remarkable new genera, even at the very moment that the manuscript of this new edition was completed in April 2007. Moreover, several genera that were known only from fragmentary type material have been rediscovered. Exploration throughout the tropics has provided new observations that have allowed detailed reassessment of genera. At the same time a vast new range of phylogenetically informative characters has become available, principally through analysis of DNA. Despite some challenging properties inherent within palm genomes, a substantial body of literature has been amassed since the publication of the first molecular phylogenetic study of palms in 1995. More than any other source, these molecular characters have allowed us to gain a thorough understanding of palm phylogenetics and to obtain sometimes dramatic new insights into both relationships and morphology. The first edition of Genera Palmarum, which was based on painstaking comparison across the family, provided a hypothesis of relationships that has now been comprehensively tested using the most up-to-date tools and methods. The new classification that we present here provides confirmation of some of the groupings recognised in the first edition, but has also revealed substantial differences and at times quite surprising discrepancies when compared with previous classifications. This new edition of Genera Palmarum is more than just a revision of the first edition. In almost every respect, it is an entirely new book. The taxonomic core of the book, namely the generic descriptions have been extensively rewritten, restructured and augmented. All other content, the notes associated with each genus, the introductory chapters and so on, have been written de novo. We have amassed the most extensive and complete selection of palm images ever published, thanks to the generosity of many contributors; only a few of these featured in the first edition. Even the illustrations have been revised, with some errors corrected and new genera illustrated by Lucy T. Smith in the characteristic style of Marion Ruff Sheehan. The team for this new Genera Palmarum came together for the first time at a meeting held at the Montgomery Botanical Center on 17 January 2003, the details of the phylogenetic classification were thrashed out at a week long summit held in the L.H. Bailey Hortorium in early June 2004. Responsibilities for each part of the book were shared out among the authors as follows. JD took on the revision of the taxonomy, descriptions and keys. He also contributed many of the notes and introductory chapters (Natural History and Conservation and the introduction to the Classification of Palms) and supplementary materials, such as the geographical listings and the literature cited. NWU supported JD closely in this commitment, and took the lead on the rewriting of Chapter 1, The Structure of Palms, with collaboration from JD and WJB. MMH contributed all chapters, notes and descriptive information on pollen and fossils. WJB wrote the introductory chapters on Chromosomes and Cytogenetics, Phylogeny and Evolution (with CBA-L) and Biogeography. CBA-L, WJB and CEL together prepared all the phylogenetic notes for the taxonomic accounts. CEL provided the Chemistry chapter and new illustrations for the glossary, which he revised with the other co-authors. JD took on the role of collating the manuscript and co-ordinating with Kew Publishing and co-authors. This new Genera Palmarum will, we hope, provide a robust framework for the studies of the palm family for many years to come. There are still areas of uncertainty, but we believe that the higher-level classification of subfamilies, tribes and subtribes is largely robust and unlikely to require substantial change. Uncertainties in inter-generic relationships and generic circumscription remain, and the field of species-level phylogenetics remains wide open. We hope that our work has the same invigorating affect that the first edition of Genera Palmarum appeared to have and look forward to reflecting, in another two decades, on the triumphs of a new generation of palm biologists.