Sierra float her soul up to her room’s ceiling and spin it like a Sufi. She writes her favorite lines in the inside covers of her field notebooks and peeks at them when department politics and the cruelty of frightened humans get her down. The words withstand the full brutality of day.
We all travel the Milky Way together, trees and men. . . . In every walk with nature one receives far more than he seeks. The clearest way into the universe is through a forest wilderness.
PLANT-PATTY becomes Dr. Pat Westerford, a way to disguise her gender in professional correspondence. Her work on tulip trees earns her a doctorate. It turns out that those thick, long lengths of culvert pipe stood on end are factories richer than anyone suspects. Liriodendron has a repertoire of scents. It breathes out volatile organic compounds that do all kinds of things. She doesn’t yet know how the system works. She just knows it’s rich and beautiful.
She lands a postdoc at Wisconsin. She searches Madison for relics of Aldo Leopold. She looks for the towering black locust, with its fragrant racemes and pea-pod seeds, the tree that stunned Muir into becoming a naturalist. But the world-changing locust was cut down twelve years before.
The postdoc turns into an adjunct position. She makes almost nothing, but life requires little. Her budget is blessedly free of those two core expenses, entertainment and status. And the woods teem with free food.
She starts to examine sugar maples, in a forest east of town. Her breakthrough comes as breakthroughs often do: by long and prepared accident. Patricia arrives in her copse on a balmy day in June to find one of her bagged trees under full-scale insect invasion. At first it seems that the last several days of data are ruined. Improvising, she keeps the samples from the damaged tree, as well as several nearby maples. Back in the lab, she widens the list of compounds she looks at. Over the next few weeks, she finds something that even she isn’t ready to believe.
Another nearby tree gets infested. She measures again. Again, she doubts the evidence. Fall begins, and the leaves of her complex chemical factories shutter and drop to the forest floor. She battens down for the winter, teaching, double-checking her results, trying to accept their crazy implications. She wanders the woods, wondering if she should publish or run the experiment for another year. The oaks in her forest shine scarlet still, the beeches a stunning bronze. It seems wise to wait.
Confirmation comes the following spring. Three more trials, and she’s convinced. The trees under attack pump out insecticides to save their lives. That much is uncontroversial. But something else in the data makes her flesh pucker: trees a little way off, untouched by the invading swarms, ramp up their own defenses when their neighbor is attacked. Something alerts them. They get wind of the disaster, and they prepare. She controls for everything she can, and the results are always the same. Only one conclusion makes any sense: The wounded trees send out alarms that other trees smell. Her maples are signaling. They’re linked together in an airborne network, sharing an immune system across acres of woodland. These brainless, stationary trunks are protecting each other.
She can’t quite let herself believe. But the data keep confirming. And on that evening when Patricia finally accepts what the measurements say, her limbs heat up and tears run down her face. For all she knows, she’s the first creature in the expanding adventure of life who has ever glimpsed this small but certain thing that evolution is up to. Life is talking to itself, and she has listened in.
She writes up the results as soberly as she can. Her report is all chemistry, concentrations, and rates—nothing but what the gas chromatography equipment records. But in her paper’s conclusion, she can’t resist suggesting what the results spell out:
The biochemical behavior of individual trees may make sense only when we see them as members of a community.
Dr. Pat Westerford’s paper gets accepted by a reputable journal. The peer reviewers raise their eyebrows, but her data are sound and no one can find any problems except common sense. On the day the article appears, Patricia feels she has discharged her debt to the world. If she dies tomorrow, she’ll still have added this one small thing to what life has come to know about itself.
The press picks up on her findings. She does an interview for a