The War Between Trees and Grasses

In his previous book, Senescence, Professor Thomas brought together his long standing interests in plant science and literature, to craft an authoritative but entertaining and relatively easy to follow scientific essay on a subject he has worked on for many years. The work offered the breadth one would expect from a review of the topic, with each key point being well referenced using up to date research results or otherwise well authored sources. A notable feature of the book was the engaging style, which owed a lot to the freedom he allowed himself, as a now retired academic, to move between the first and third person narrative, blending science with, inter alia, apposite quotations, longer literary passages, cultural asides and pithy commentary.

In the War between Trees and Grasses, the author adopts a similar style to give us a highly readable account of how the evolutionary development of and reciprocal interactions between trees, grasses and man have played out over time.

The book is divided into digestible mini chapters that closely follow the development of life over geological time after emerging from water onto land. The first chapters elaborate on how the need for water control encouraged compartmentalisation, which in tandem with controlled senescence allowed the development of primitive vascular systems. The first arboreal habit was based on a simple modular form composed of repeating phytomer units, exemplified in sporophytic plants like ferns and horsetails, a forest of such giant specimens becoming the dominant biome. This in turn was replaced by the development of seed plants, the gymnosperms, and then flowering plants, the angiosperms. The next few chapters, consider the abiotic and biotic factors that led to plant diversification and the development of non-woody, herbaceous or otherwise short-lived species, including the divergence, details of which are still uncertain, into dicotyledonous and monocotyledonous forms. Thomas then develops the idea of grasses as anti-trees, i.e their ability to adapt to conditions inimical to trees, allowing them to flourish in particular habitats and conditions. They are less prone for example to damage from fire, and quickly recolonise burnt wooded areas. Changes in climate also favoured grasses, they are generally more tolerant of drier conditions, especially those that developed water efficient C4 photosynthetic pathways.

The price for success in competing with trees was that grasses became prime targets for herbivores, leading to an escalating literal war of attrition in which grasses developed deterrent strategies such as silica reinforced leaves and a host of unpleasant chemicals, whilst herds of grazing animals developed in size and numbers as they become more efficient at converting this food-source into protein.

The remaining chapters of the book look at how humans have exploited grasses, trees and the animals feeding on them, and charts the physiological changes and cultural influences attendant on this process. The development of starchy grains in grasses and man’s exploitation of this feature, has been key to sustaining and developing our large brains; brains that are capable of understanding agency, a term Howard borrows from the social sciences to describe the reciprocal interactions that influence evolutionary fitness and survival, and perhaps some inkling of our part in this engagement.

Slim in size but not slight in content, this inexpensive book would make an ideal introduction for students following courses in plant evolutionary development or tree biology. It provides a concise summary of key scientific ideas and processes, all of which are well referenced. The illustrations and accompanying text boxes nicely complement the narrative and there is a useful combined glossary and index, bibliography and other helpful appendices. The book is also highly recommended to more general readers with an interest in botany or the relationship between people and plants.

Author
Born and educated in Wales, after a career in scientific research, Howard Thomas is now emeritus Professor of Biology at Aberystwyth University. This allows him to carry on as he says ‘with all the nice parts of the old job (writing, research, hanging round with other scientists, journal business, drinking too much coffee), much to the envy of my hard-working friends and colleagues who have to do all this as well as admin, politics and fund-raising. It means that I’ve been able to indulge a long-standing special interest in the science-humanities connection. I’ve also led a parallel life as a devout jazz musician.’