Plant Life is a concise but incredibly thorough summary of all the major trends at play in the origin and diversification of land plants. This is by no means a straightforward subject, but Frederick Essig does a truly admirable job of condensing huge amounts of information into an easily digestible form. The writing is perhaps more technical than a typical popular science book, but Plant Lifeprovides a perfect overview for anyone from the advanced undergraduate level on up—even a committed, nonscientist plant enthusiast.
The origin and diversification of the land plants constitute a compelling tale and a critical component of the evolution of life on Earth. However, as any botanist will tell you, plants often get short shrift in textbooks and are too frequently dismissed as “boring” by young undergraduates. As I have discovered in my own teaching experience, the best way to combat these misconceptions is to present the material as a logical arc, drawing on the diverse, fascinating examples of plant problem solving to punctuate the journey. This is exactly the approach taken by Essig in this lovely book. He covers the entire history of plant diversification in nine compact chapters, leaving almost no stone—or perhaps we should say leaf—unturned.
Essig starts at the ultimate beginning, with the origins of life and the crucial origin of photosynthesis in prokaryotic organisms. He explains the basic functional modules that act in photosynthesis and how they were likely assembled through horizontal gene transfer during the evolution of the free-living ancestor of the chloroplast. From here, he transitions to a consideration of the evolution of eukaryotes and how their capture of photosynthetic prokaryotic organisms led to the derivation of the permanent chloroplast. At the same time, he provides an overview of algal diversity and the critical subject of life-cycle patterns, especially the distinction between haploid-dominant life cycles and the true alternation of generations, which characterizes land plants. In the book's third chapter, he makes the transition onto land and does an excellent job of contrasting the living representatives of the early land-plant lineages, collectively known as the bryophytes, with the more complex fossil history of this period. He also covers the major innovations evolved by these early land plants, specifically desiccation tolerance, the different mechanisms of water transport, and the key modifications of the ancestral algal life cycle. Likewise, in the chapter on vascular plants, Essig gives significant consideration to the origin of major sporophyte characteristics such as roots, leaves, and wood while incorporating a useful discussion of extant versus fossil plants. Next in line is the seed-plant lineage. Explaining the evolution of the seed and how the alternation of generations is expressed in this clade is a tricky business, but Essig manages it quite well. The remainder of the volume is given over to the angiosperms, the dominant group of extant land plants.
Here, the author takes full advantage of fossil and living exemplars to explore the origin of the angiosperms, as well as their morphological, physiological, and ecological diversification. Plant–animal interactions get special attention in a dedicated chapter on adaptations for pollination and seed dispersal, which allows the author an opportunity to explore a wide array of ecological and morphological specializations. I was quite pleased to see that in the separate chapters on dicots and monocots, aspects of functional morphology such as vascular structure and habit (i.e., woody versus herbaceous) receive full coverage. These are crucial traits that often get short shrift in the common focus on seed-plant reproductive biology. Finally, the blunt and somewhat bleak epilogue is nonetheless honest and scientifically accurate. We can only hope that, through the efforts of authors such as Professor Essig, more people will become engaged with the natural world and press for the policy changes that would be necessary to rescue plant biodiversity and ourselves in the process.