BOOK REVIEW University Press of Florida April 1, 2019 6 x 9 in., 274 pages ISBN: 978-0-8130-6408-6
Plants live their lives just as we do, surrounded by loved ones, competitors.and enemies; seeking to find harmony and health; and hoping to leave behind a legacy of well-adjusted progeny capable of carrying on after their demise. Like us, they have evolved complicated pathways and behaviors to accomplish this. We are not really that different …
Craig Huegel’s The Nature of Plants is a thorough introduction to the features and functions of plants (with an emphasis on flowering plants). Though Huegel has been a professor of plant biology, he says he is “a gardener first and a biologist second.” Consequently, his aim in this book is “to teach gardeners and others who love plants how to apply plant biology to make their work with plants more successful and to unlock some of the mysteries in a practical way so that more gardens thrive and fewer plants die.” He hopes, along the way, to also give “a deeper appreciation for how intricate and interesting plants are.” While he may be more successful in the latter aim than the former, this is a brilliant book that deserves a place on any gardener or plant lover’s shelf. (I got the copy I used for this review from the library, and after reading it I ordered a personal copy for the permanent collection.)
The most striking thing about Huegel’s approach is the agency that he attributes to plants. He sees plants as actively making decisions about how to deal with their environment (even suggesting that these decisions may be directed by a sort of brain in the rootball). “Plants,” he says, “are far more complex than we have traditionally perceived them to be; in some ways they are even more complex than animals…. Plants must do everything animals do while remaining in the same location for the duration of their lives.” At times the tone may come across as anthropomorphizing, but readers should be able to decide for themselves to what extent to interpret such views of plant behaviors as metaphors.
Huegel systematically details the issues plants deal with, often sharing recent scientific discoveries. After an introduction to the evolution of plant species, he methodically considers plants’ interactions with light, water, and soil. He looks at plant structure and growth, and considers in detail their roots, stems, leaves, reproduction, seeds, and hormones. Finally, he look at the ways plants communicate with their offspring, others of the same species, and plants of other species.
The value of this book is not so much in specific gardening tips, although Huegel does offer some of these, such as the importance of pruning with clean sharp tools when plants are in good health, or the value of leaving leaves and spent plants to provide nutrients to the soil. (“Balance in soil fertility is often upset in developed landscapes,” he observes “especially when plants are harvested and not allowed to decompose on-site. Modern agriculture is perhaps the worst culprit in this scenario. We often call such soils ‘overworked,’ but it is not the ‘work’ that upsets the balance but the fact that the plants are routinely removed with all their sequestered essential elements and taken out of the system. Over time, the parent material cannot replace the amount lost.”) Rather, its chief value lies in its comprehensive overview of plant lives and functions.
Throughout his exploration of the many facets of plant life, Huegel shares his respect for their intelligence. Did you know, for example, that plants are good at math? “Plants adjust their basic metabolic rate on a daily basis. They are frugal; plants spend less energy on their metabolism than they earn each day, and they put something aside even on days when they earn very little. Plant biologists have found that plants have an internal mechanism that calculates daily the amount of energy they’ve gained and divides it by the length of the night. This solves the problem of how to portion out energy reserves during the night so that the plant can maintain itself, yet not risk burning off all its energy reserves before starting a new day. The calculations plants make are extremely precise.”
Similarly, “Plants make accurate judgments each day about when sunrise will occur, and they position their leaves and/or flowers in unison with it.” Huegel is keen on flowering plants. “Although many of my neighbors relish warm winters, I despise them,” he says (because some plants require a cold period in order to produce abundant flowers). “I can always wear a coat if it gets cold, but I have to wait another year to experience my flowers”
Or again, “Research has shown that the style portion of the flower can make decision on which pollen it will accept based on the sex ratio of the plants around it, the overall fitness of the potential mates, and their relatedness. These are much the same decisions that animals make in choosing their mates.”
Given these views it is not surprising to hear Huegel say that “though I do not presume to argue the morality of taking a plant life over an aniimal one, it cannot be argued that seeds do not contain baby plants and that baby plants are not alive and aware of their status and surroundings.”
Huegel’s view tends to be teleological. He sees the development of flowering plants — which comprise about 80 percent of the total number of plant species today — as an advance, an improvement over earlier types of plants, such as ferns, for example. I would prefer not to place such value judgments on the course of evolution. Flowering plants are making a big bet on pollinators, and who is to say that they might not suffer a correspondingly big kill-off in our Anthropocene age? If that were to happen, ferns’ reliance on ancient methods of reproduction might not look so backward after all.
But that is a minor objection. Huegel is particularly good on plant hormones, which are used to allocate resources, respond to threats, and regulate and time the production of their sexual processes. He is also good on the ways plants communicate with one another, both above ground with the controlled release of volatile organic compounds (“When we mow our lawn and sense that smell of freshly cut grass, we are picking up the lawn’s alarm call telling the plants around them that danger is nearby”) and underground through their own roots, along with symbiotic bacteria and fungi. Fungal networks in particular provide plants with the ability to communicate across long distances, to favor their own offspring with essential resources and also to communicate with others of their own and different species.
Valuable as its practical observations are, this book’s systematic analysis of how plants work is its most important contribution, both to gardeners and to others interested in plant life. For, as Huegel says, “When we understand plants, we understand the foundation of life on earth.”