Phyllotaxis and Symmetry in Angiosperms

About this book

Symmetry and the causes of shifts in different types of symmetries in flowers follow specific patterns that are ruled by developmental and genetic factors. Using a unified system of phyllotaxic equations (phyllotaxis being the arrangement of leaves on a plant stem), the authors have modelled the molecular mechanisms and pressure forces that act in inflorescence and floral meristems, giving flowers their organ arrangement. In this book, the authors state general physical principles, whereby the symmetry of the perianth is derived from the symmetry of certain TCP gene expression. Thus, they define the interplay between the expression of CYC2-like genes and the phyllotactic mechanisms.

This new evo-devo approach is applied to major groups of angiosperms with predominantly actinomorphic (i.e. radially symmetrical) flowers (in which rare zygomorphy, i.e. floral parts being unequal in size or form, is positional) and groups with mainly bilaterally symmetrical flowers (in which zygomorphy is constitutional). It has thus allowed the authors to revisit the contributions of the great floral morphologists of the 20th and early 21st centuries.

Contents

Foreword   ix
Preface   xi
Acknowledgments   xv
Introduction   xvii

Chapter 1. Concepts of Phyllotaxis and the Genetics of Floral Symmetry   1
Chapter 2. Spirals Are Symmetrical Figures   23
Chapter 3. Symmetry in Ranunculales   53
Chapter 4. Symmetry in Lamiales   83
Chapter 5. Constitutional versus Positional Monosymmetry   101
Chapter 6. Symmetry in Fabales   139
Chapter 7. Symmetry in Monocots   155

Conclusion   181
References   201
Index   217

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Biography

Jean-Paul Walch is a former Computer Scientist who has worked for several large French companies in the oil and electricity distribution sectors.

Solange Blaiseis a former Associate Professor at the Laboratoire Ecologie, Systematique, Evolution, Universite Paris-Sud, France.