Chapter 1 deals with transpiration and how plants employ convection and evaporation to cool themselves and their surroundings. The author peppers his subject with facts emphasizing the importance of water to plant life. Thus, we learn that a full sized maple tree growing in an open field can lose up to 200 liters of water on a sunny warm day, while a full grown corn plant can dispose of the equivalent amount of water during its lifetime. When we pass from the aerial to the subterranean domain, we also learn that a rye plant's root system can increase 5 km in total length per day to achieve a total length of 622 km. Turning to the ascent of water in trees, the author adds his first historical thread by pointing out that the cohesion theory was prefigured as early as 1727 by the cleric and scientist Stephen Hales who hypothesized that "perspiring leaves" have the power to pull water through the woody tissues of plants.
The leitmotif of water is extended and varied in Chapter 2 where the reader is introduced to the basics of photosynthesis, the process by which plants manufacture their own substance using the energy of star light. Here, we learn about the French chemist Antoine Lavoisier who advanced the notion that animals "burn" carbon and hydrogen-bearing compounds as they respire, that the Belgian physician Jan Bapista van Helmont adduced plants draw less from the soil and more from the air as they increase in mass, and that van Helmont's Dutch counterpart Jan Ingen-Housz was the first to notice that plants release oxygen but only when placed in the light.
The topic of respiration is picked up in Chapter 3, where the author gives special attention to fermentation and the alternative cyanide-resistant, heat production pathway used by plants to facilitate pollination (e.g., Symplocarpus foetidus, Dryas octopetala, and Papaver radicatum) or to melt the snow (e.g., Crocus and Narcissus). We are also treated to a thoughtful discussion of how compounds in the respiratory chain are siphoned off to produce the huge array of chemicals essential to plant growth, survival, and reproduction such as the leaf waxes, the chlorophylls, the nucleic acids, and hormones like the gibberellins. There is even a treatment of the ability of roots to deal with oxygen starvation which varies widely across species. Chapters 4 and 5 continue the topic of plant metabolism, especially the requirements for nitrogen and trace minerals and the roles roots play in recycling materials as they "mine" the soil.
Chapter 6 introduces the plant's supercellular transport systems, the xylem and the phloem tissues, which are responsible for the movement of water and nutrients. In this chapter we read about Marcello Malpighi's girdling experiments that showed materials are transported downward as well as up along the lengths of tree trunks (although he failed to appreciate that two different tissue systems are involved). The author then takes up the topic of metabolic sources and sinks and discusses how mature leaves nourish and abed the growth of more distal, juvenile leaves.
Growth substances are given their due in Chapter 7 but only after Prof. King convinces us that the rates and achievements of plant growth can be stunning (by pointing out that some bamboo shoots grow over a meter in length a day and that a giant redwood increases in size 250 billion times from seed to mature specimen). Prof. King takes obvious delight in telling us about Charles and Francis Darwin, who were the first to observe, record, and ponder the operation of plant growth substances using Phalaris canariense seedlings. Indeed, the Darwins were the first to conclude that the tips of these seedlings "sensed the light," thus paving the way for Fritz Went who restored the ability of decapitated seedlings to bend toward the light by means of chemical extracts, and for Fritz Kögl's subsequent isolation of 40 mg of crystalline auxin from about 180 liters of human urine. Eiichi Kurosawa's experiments with "silly rice disease" and the Gibberella fungus, the identification of the cytokinins purified from corn seeds, and the first glimmerings into the roles of ethylene from the behavior of German street trees growing near leaking gas mains in the 1860's are also artfully presented and enjoyably discussed with authority.
Circadian plant rhythms are dealt with in the following two chapters where we read about the experiments of Jean Jacques d'Ortour de Mairan, a French astronomer, who adduce internal biological clocks by watching the movements of Mimosa leaves well over 200 years ago. We also learn about the fastidious habits of Rose Stoppel whose punctilious but misguided attempts to water bean plants in a darkened room with a flashlight covered with dark red paper helped Erwin Buenning, Kurt Stem, and, later, others like Edward D. McAlister, Lewis H. Flint, Harry Borthwick and Sterling Hendricks to comprehend the existence of phytochrome whose chemical states help to reset natural rhythms to a 24-hour cycle. In these chapters we also learn about the tragic death of a brilliant doctoral student in Paris, Julien Toumois, who, by studying hops and hemp, concluded that it was the length of the night and not the shortness of the day that dictated when his plants flowered. The seminal work of Garner and Allard, who coined the terms photoperiodism and short- and long-day plants, is also nicely described and pondered.
The remaining chapters deal with dormancy (chapter 10), the slings and arrows of outrageous ecological fortunes (chapter I 1), the importance of color, odor, and flavor to pollination and seed or fruit dispersal (chapters 12 and 13), the use of secondary and primary metabolites in chemical warfare (chapters 14 and 15), phyto-pharmacology and ethnobotany (chapter 16), and finally programmed senescence and the inexorable process of death (chapter 17).
Any book treating such a diverse assembly of topics cannot escape the occasional lapse or error. The ascicular leaves of cacti are referred to as thorns instead of spines. The tensile strength of water is given without qualification or reference to the adhesive effects or dimensions of its containment vessel. There is an unfortunate tendency to ascribe consciousness or intent to the "minds of vegetables" or the evolutionary process. The book also unintentionally perpetuates the myth (stubbornly ingrained in so many text books) that the first sugar produced by photosynthesis is glucose (it's really phosphoglyceraldehyde). And there is a curious mix of metric and old British Imperial units. But this is nit-picking, pure and simple, and should not detract from an otherwise masterful treatment that is all the more remarkable given the complete absence of drawings, photographs, tables or any other graphic devise.
John King's Reaching for the Sun is bound to have influence because it could easily be adopted as the text for an undergraduate course requiring little or no prior background in biology or as intriguing and enjoyable bedside reading material, especially when placed along side F. O. Bower's Plants and Man, Sherwin Carlquist's Island Life, and E. J. H. Corner's The Life of Plants. These four books will undoubtedly deprive you of sleep, but you will be richly rewarded with the insights of sharp minds that command respect as they speak to us with passion, clarity, and exemplary bio-logic - Karl J. Niklas, Section of Plant Biology, Cornell University