Plants that Kill by Elizabeth A. Dauncey and Sonny Larsson
Reviewed by Ian Lipke
Elizabeth Dauncey and Sonny Larsson have provided the world with a book that is detailed and comprehensive in the information it supplies while, at the same time, is a model of simplicity in its outlay and in allowing the reader to find quickly the particular piece of information being sought. It has been a long time since I was as impressed as I am by Plants that Kill.
The reason for the clarity of the presentation may lie in the fact that Elizabeth Dauncey is a freelance toxicologist and the author of a volume that guides parents and child care providers about poisonous plants. Her co-writer Sonny Larsson is a licensed pharmacist at the Swedish Poisons Information Centre. Hence both authors are well qualified to write about plants that can cause suffering.
The structure of the book is pretty simple. There is an introduction which uses both language and diagrams to explain how the material is assembled. Ten chapters follow. Chapter One explains why some plants are toxic. The argument is this: plants cannot run away from herbivores, so they need alternative ways to deter predators. “One such strategy is by chemical means, producing poisonous and noxious compounds that deter feeding and infection” (11). The chapter explains what a plant is and how scientists describe plant diversity, it explains why and how plants produce toxins, and why the plants themselves are immune to the poison.
The chapter tackles head-on the issue of how to distinguish plants from animals. This seems trite until we recall that we know of organisms such as the sessile that are more closely related to animals than to plants. ‘What is a plant’ is answered in a double page spread and this same structure is maintained, with the exception of the treatment of cardiac glucosides – cardenolides (57 – 58) that requires more than the two-page spread. So Chapter One continues with classification and nomenclature, evolution with its principles of heredity, root to leaf, flowers, fruits and seeds, photosynthesis and metabolic pathways, finishing with small molecular compounds.
It is important that the layout of the book and the treatment of the material in each chapter be understood. On pages 26 -27 Dauncey et.al. in an introductory couple of sentences explain that chemical compounds are divided into groups but “there is no evidence that chemical groups are hierarchical or evolutionary, in the sense that we cannot trace all compounds back to a single common ancestral substance” (26). The authors then group substances based on their chemical properties or how organisms synthesize them. What follows are discussions of polyketides and acetogenins, terpenes, alkaloids and saponins. There are diagrams showing chemical structures and photographs of edible palm oil and the source of the drug Radix Polygalae Tenuifoliae. Polygala tenuifoliae is a saponin, and the authors do not shirk from admitting that the mechanisms by which saponins operate is unclear.
I have gone to some depth to explain how the chapters in this book are laid out. Chapter Two is called Targets in the Body and, as in Chapter One, the contents of the chapter are laid out before the chapter begins. Here the authors intend to give an overview of how the human organism functions and its array of targets for plant poisons. The normal functions of human systems are linked to the potential mechanisms of toxins, while the chapter considers differential effects of toxins on animals. As an example of this last point the authors say, “Plants produce compounds that provide protection, while animals, fungi and bacteria develop ways of evading these toxins. But it is not always that straightforward; sometimes, a kind of collaboration evolves” (42).
Chapter Three looks at the plants and toxins that threaten the rhythm of the heart, Chapter Four explores examples of poisons affecting the brain and central nervous system, while other chapters in turn deal with the effects on nerve-signalling, on the skin, and in the gut. Chapter Eight explores examples of inhibition, stimulation, and tricking of the normal functions of the liver or kidneys, while Chaptr Nine takes a conservative approach to reporting on cell poisons, and the last chapter reports that some poisonous plants can be utilized for medicinal purposes.
The book concludes with an extremely valuable glossary, examples of further reading, some online resources and a comprehensive index.
Somebody described this book as “stunningly illustrated”. I would have to agree. The pictures are not so small as to be useless for detailed study, nor too large so as to be brash and unrestrained. A happy medium has been reached so that the book presents itself as a serious, dignified publication. It supplies references to figures in history and to current events. It is an excellent text for the academic and general reader alike. I love it!
Plants that Kill (2018) ISBN: 978-0-691-17876-9
By Elizabeth A. Dauncey and Sonny Larsson