Opportunism, Resistance, Folly: Our Complicated Relationship With Weeds
Lives of Weeds explores the tangled history of weeds and their relationship to humans. Through eight interwoven stories, John Cardina offers a fresh perspective on how these tenacious plants came about, why they are both inevitable and essential, and how their ecological success is ensured by determined efforts to eradicate them. Linking botany, history, ecology, and evolutionary biology to the social dimensions of humanity’s ancient struggle with feral flora, Cardina shows how weeds have shaped — and are shaped by — the way we live in the natural world.
Read below for an excerpt from the book’s introduction.
Weeds come, and weeds go. Not only do the species change, but the view of what is, or is not, a weed continues to change over time and place. Neither weeds nor weediness are static. No wonder there is no fixed botanical definition of “weed” or timeless agreement on which plants merit such derision. Humans have helped to make thorny thugs and to unmake them. Plants that any farmer or gardener would recognize as a pest today were not always so. Most of the species discussed in these chapters were at one time considered desirable, or at least innocuous. Some were coveted, protected, and enjoyed for ornamental, medicinal, culinary, or other practical purposes. Conversely, the thorniest enemies of farmers of old include some species that are insignificant today; some can hardly be found.
My favorite example comes from William Darlington’s 1847 botany book in which he itemized the most serious weeds of North American agriculture. His list included oxeye daisy, star-of-Bethlehem, and bracted plantain.9 Similarly, The First Ohio Weed Book, written by A. D. Selby, ranked red sorrel among the most troublesome plants facing Ohio farmers in 1897.10 I’ve presented these lists to many farmers and gardeners. Most have never heard of these weeds or regarded them as problems.
The reason is simple. Farm fields of the 1800s went without lime, and soils were acid. Crop seeds of that era were contaminated with seeds of acid-tolerant daisies, plantains, red sorrel, and others. Modern gardeners and farmers, with mechanization, better managed soils, and efficient seed cleaning have other weeds to contend with, those they’ve inadvertently favored by modern means. The weeds that American farmers consider most troublesome today include marestail, waterhemp, and Palmer amaranth.11 Neither Darlington nor Selby even mentioned these plants as objectionable. In fact, these species weren’t on any list of troublesome weeds ten years ago.
Weeds come and go across cultures as well as in time. I recently asked an Amish friend which species were most bothersome to him. He is an excellent farmer with fine crops of hay, grains, and vegetables. I drove past fields infested with ragweeds, pigweeds, and foxtails to get to his farm, which operates with draft horses and practices dating to the 1800s. He explained that throughout the whole Amish community in the hills of eastern Ohio, the most vexing plant is yellow buttercup. It grows in horse pastures. No matter how low you cut them, they survive and compete with the grasses and clovers that sustain the main source of power for the farm — horse power. Foxtails and pigweeds, he explained, follow compaction by heavy equipment and are not problems on Amish farms, where horses do the work.
These examples explain why weeds are social, cultural, psychological phenomena as much as they are biological wonders. Most efforts to “control” unwanted vegetation rely on technological solutions that are blind to this deeper essence. The result is ultimately frustration, which works to the weeds’ benefit. The deeper essence of weeds is revealed in the attitudes and behaviors of humans, which are the source of the frustration. This does not minimize the serious economic and practical problems that noxious grasses and broadleaves cause for farmers of every crop throughout the world. Understanding weeds in all their dimensions, and appreciating their biocultural histories, illustrates how certain plants became especially troublesome and how changes in attitudes and behaviors might help make them less so.
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The eight paths to weediness that I’ll describe represent just a few of the coevolutionary trails that humans and unwanted leafy companions have traveled. They all show how agrestal selection has driven changes in plant populations, usually for the benefit of the weeds. They also show how humans, with mostly good intentions, have modified undesirable flora in more than a biological sense and given them meaning that ordinary, inconsequential plants lack. The trajectory of the stories from the suburban world of dandelion to the global impact of ragweeds is one of increasing severity and impact on human health and the environment. I end with foxtail, from a group of grasses that can be weeds or crops or wild or waifs, representing the hopeful imagining of different possibilities and choices for how plants can be, and maybe humans as well.
Ultimately, this book is about our role in the natural history of weeds. I’ve attempted to give appropriate attention to the behavior and consequences of the other half of what the word weed signifies. Humans and weeds have been ecologically successful because of our remarkable ability to adapt to conditions around the world. The ability to survive in a wide range of environments comes from a long history of accumulating genetic variation and, specifically, genes for plasticity. Humans, with our big brains that give us the ability to use symbols, explore, and create, can harness our collective good will to sustain the planet for the happiness of future generations. Or we can ignore what we’re capable of and rely on our baser — weedier — instincts to simply grab more for ourselves.
Inevitably, natural histories that intersect with human history will have winners and losers, conflicts, and uncertainties. Natural histories don’t offer solutions. They are an accounting of how we got where we are today. These chapters tell how we got the weeds that farmers and gardeners face now, why pest plants persist despite increasingly sophisticated chemical and genetic technologies aimed against them, and how all of us are part of that. Going forward, we can learn from this history. Or not. Learning from it means all the things reasonable people already know about how to live on this planet in ways that are more respectful of the environment, the biosphere, and each other. Because weeds are known to everybody, the stories of personal interplay with humble botanical accomplices are a way to explore consequences of modern life that might not be appreciated. My hope is that these narratives will stimulate interest in evolutionary biology and provide some basic language to help make the science more approachable so that better understanding will lead to better decisions about how to live, how to eat, how to vote, how to appreciate and enjoy the natural world.
