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Books biology, I certainly believe that pluralism is appropriate when assessing textbooks. There are many different virtues that one might aspire to in an introductory text, including brevity, clarity, insightfulness, detailed examples, and rigorous philosophical argumentation. Godfrey-Smith’s text rates very highly on the first three desiderata: It provides a clear and concise introduction to the philosophical issues that arise in connection with biology. Readers will encounter stimulating and fresh perspectives on central topics, delivered by an author with a remarkable command of the field. But those who hunger for detailed examples and a richer assessment of arguments may be better served by other texts. TODD GRANTHAM Todd Grantham (granthamt@cofc. edu) is a professor and chair of the philosophy department at the College of Charleston, in Charleston, South Carolina. doi:10.1093/biosci/biu206 WHY PLANT PHYSICS? Plant Physics. Karl Niklas and Hans-Christof Spatz. University of Chicago Press, 2012. 448 pp., illus. $60.00 (ISBN 9780226586328 cloth). K arl Niklas and Hans-Christof Spatz, both highly respected when it comes to the structural analysis of plant tissues, have brought forward a significant addition to the literature on plant structure. Plant Physics presents a comprehensive overview of the physics relevant to the structural economy of land plants. The topics covered include a concise introduction to the principles of structural mechanics, fluid dynamics, and electrophysiology, with in-depth coverage of plant–water relations and environmental biophysics. The topics are amply referenced, and the book concludes with chapters http://bioscience.oxfordjournals.org on experimental and theoretical tools and a glossary. But why should you have a book on plant physics on your shelf? Isn’t plant structure simply the downstream manifestation of complex but familiar cellular and molecular mechanisms working within a particular set of physical constraints, or is there something more fundamental that sets plants apart? In animals, the emergence of biological form during embryogenesis and growth is hugely complex. Signal processing, rapid nerve transmission, and muscular control must all be coordinated during development—never mind the various kinds of social interaction and consciousness that animals might enjoy. The prospect of articulating a developmental narrative that can encompass all of these processes is probably still unattainable, which forces us to deal with each subsystem individually, as its own discipline (Niklas 2012). But in the plant kingdom, development is more transparent. This is because of the constraints that the cellulosic cell wall has placed on the evolution of morphospace. In the land plants, all somatic cells are permanently trapped within a continuous fabric of rigid cellulosic cell walls, which thereby eliminates any possibility of cell migration. One consequence of the universal presence of the cell wall is that land plants, rooted in what is essentially a freshwater environment, routinely develop cellular turgor pressures that can only be considered extreme by metazoan standards. Pressures of up to 1.0 megapascal are commonplace in expanding plant cells. The plant body can be regarded as a collection of pressure vessels embedded in a more or less rigid matrix, whose properties have to be finely tuned in order to control growth. Cell division becomes restricted to the terminal meristems where new cells are formed, just as adding new floors at the top of a skyscraper creates new living space. Construction of the plant body becomes something of an engineering problem. Furthermore, although plants and animals have similar cytoskeletal mechanisms for chromosomal assortment, cell division in the plant kingdom is functionally very different from animal cell division. In the plant kingdom, the products of mitosis are permanently bonded to one another, with the whole plant forming a single mechanically continuous structure. Cells divide by precisely orienting new partition walls, much as an architect would erect a new partition across an existing room, establishing a spatial relationship between daughter cells that can never change. Animal cell mitosis, however, involves a cell essentially pinching in two, after which the two “daughter” cells are, at least in principle, free to move independently to create new neighborhoods and to foster functional relationships in ways that are unavailable to plant cells. Morphogenesis can involve cell migration and flow. But in the land plants, in which cells are pressurized and frozen in place, the development of form becomes an architectural process, in which the permanent installation of precisely oriented partition walls is necessary to support the turgordependent tissue stresses that radiate throughout the growing tissues. So while evolutionary constraints have resulted in a developmental paradigm that seems simpler than that of animals, they have also endowed plants with a suite of mechanical and biophysical tools that are largely unavailable to animals. This amounts to a unique evolutionary context, a structurally based information system that can inform developmental events with a spatial February 2015 / Vol. 65 No. 2 • BioScience 215 Books How to Contact AIBS BioScience Advertising, print and online: [email protected] Classified advertising: [email protected] 855-895-5374 Online: http://bioscience.oxfordjournals.org Permissions: [email protected] Publisher: [email protected] 703-674-2500 x. 258 Submission inquiries: [email protected] 703-674-2500 x. 326 Subscriptions: Individual [email protected] 703-674-2500 x. 247 AIBS ActionBioscience.org: [email protected] 703-674-2500 x. 326 Education Office: [email protected] 703-674-2500 x. 311 Executive Director: [email protected] 703-674-2500 x. 258 Membership Records: [email protected] 703-674-2500 x. 247 Community Programs: [email protected] 941-321-1573 and temporal resolution accessible only to physical and mechanical systems. It should come as no surprise that since the emergence of plants onto the land surface perhaps a billion years ago, the evolution of plant morphospace has been shaped by physical mechanics and the nanostructural behavior of the wall itself. Plant growth and morphogenesis is increasingly being regarded as being coordinated and regulated by physical and mechanical feedbacks working at the tissue level. (Sampathkumar et al. 2014). Physics and physical mechanics are abundantly evident everywhere we look in the plant kingdom—whether in the tallest trees, rising more than 100 meters above the land surface, or in the energy-storage and vibrationdamping characteristics of a finely crafted split bamboo fly rod. At the level of basic research, we are beginning to appreciate the full extent to which the behavior of plant cells and tissues is intimately tied to the biomechanics and biophysics of the cell wall (Niklas 2014). It is becoming increasingly clear that the evolution of plant form has been driven by innovation in the m aterial properties of the cell wall at the u ltra- and n anostructural levels. Plant developmental ontogeny turns out to be profoundly different from that of animals and should be regarded as a sui generis morphogenetic paradigm that must be understood on its own terms. It is possible, in fact, that the land plants may offer us our first opportunity to articulate a comprehensive narrative that encompasses molecular and genetic subsystems while framing the flow of morphogenesis within a clear biophysical context (Lintilhac 2014). Niklas and Spatz approach the material as experts who have dealt with most of the salient biomechanical issues of plant structure, hydrodynamics, and aerodynamics. They explore the physics of gas exchange, transpiration, fluid dynamics, structural mechanics, membrane electrophysiology, the strength and acoustic properties of wood, and more. But this is not just a textbook. For the plant biologist, this book will be an invaluable reference for many years. For the physicist, the attraction of this book may be the breadth of topics covered and the implication that physics lies at the very heart of plant developmental biology. As biologists, we have coveted what physics takes for granted, which is a theoretical continuity between the symmetries of matter and energy at the subatomic level and our growing understanding of the organization of the cosmos as a whole. Can we contemplate a time when a similar continuity might emerge in the biological sciences? References cited Niklas KJ. 2014. The evolutionary-developmental origins of multicellularity. American Journal of Botany 101: 6–25. Sampathkumar A, Yan A, Krupinski P, Meyerowitz EM. 2014. Physical forces regulate plant development and morphogenesis. Current Biology 24: R475–R483. Lintilhac PM. 2014. The problem of morphogenesis: Unscripted biophysical control systems in plants. Protoplasma 251: 25–36. PHILIP LINTILHAC Philip Lintilhac (philip.lintilhac@uvm. edu) is a research associate professor in the Department of Plant Biology at the University of Vermont, in Burlington. doi:10.1093/biosci/biu191 Public Policy Office: [email protected] 202-628-1500 x. 250 Scientific Peer-Review Services: [email protected] 703-674-2500 x. 202 Web/IT Services: [email protected] 703-674-2500 x. 107 216 BioScience • February 2015 / Vol. 65 No. 2 http://bioscience.oxfordjournals.org