Plants keep getting smarter, even in my yard, as we slow down and study them
“Now I know what you’re up to,” I say to the plants in my garden as I pull on gloves and pick up the trowel and clippers. “And it’s not just growing.”
I recently read an article by Michael Pollan, “The Intelligent Plant,” about scientists exploring “the possibility that plants are much more intelligent and much more like us than most people think—capable of cognition, communication, information processing, computation, learning, and memory.”
While these ideas can be controversial, he suggests we humans would see and appreciate this intelligence if we could slow down enough, for “the lives of plants unfold in a much slower dimension of time.” I happened to pick up the five-year-old issue of the New Yorker that carried this article when I flopped on the couch to rest after gardening. Ironically, my time with plants had slowed me down enough to read about them.
Until now, I figured the relaxation and sense of wellbeing I get from yard work are the result of sheer physical labor. Recently, I also read that we may feel happier from contact with soil microbes, whose compatriots in our gastrointestinal tracks help keep us healthy.
As I browsed through the various scientists’ speculations and findings in Pollan’s article, some of the signs of plant intelligence began to look familiar. Over decades of gardening the same plot of land, I may have seen similar behaviors, and here are a few.
Sensing where to reach: Experiments by Stefano Mancuso, an Italian scientist, demonstrate that young bean plants know where a supporting pole is beforethey reach for it. I’ve always suspected this of our kiwi plant, which sends out vines toward the power line leading to the house.
The kiwi has never touched this line, for my husband and fellow gardener trims it relentlessly. Yet it just as stubbornly keeps reaching for what it knows is there. We all wonder how it does this, and Mancuso suggests beans may use a form of echolocation.
Does this mean the pea vines in my garden will find their supporting strings on their own? Each spring, I carefully guide their little green tendrils toward the twine, and within seconds they start to curl in a grabbing motion. It’s the fastest plant movement I’ve ever seen, short of the snap of a Venus flytrap.
Apparently, the peas don’t need my help. In fact, this year they found their supports on their own while we were gone on a trip, and they’ve held on just fine.
Moving around—over time: Pollan notes that plants have a remarkable ability to draw everything they need for life while rooted in one spot. But over the years, my garden plants have moved themselves around. Granted, the progress is slow in human terms.
The sage plant has moved more than three feet by sending branches creeping along the ground, sprouting roots from those, and gradually weaning itself from the older root. Similarly, asparagus sprouts up on a steady march toward the south and stronger sunlight. This year, some lupine made a fifty-yard dash from front yard to back, in one season. Even the flag iris scooted under the fence and into the neighbor’s yard.
Helping family and friends: Some scientists are looking into how plants actively share resources. They’ve found those of the same variety will lend each other support when they share the same pot, Pollan writes.
This is true of the basil plants I put together in a large pot: they often grow more vigorously than ones that stand alone in separate pots. And I’d been separating them to give each more light and space—apparently a mistake.
And take the case of the lonely clematis. It wasn’t thriving, so I planted another nearby, imagining it would grow up the trellis in place of the first. But that’s not what happened. The first clematis twined with its companion, livened up, and started blooming merrily.
Researchers at the University of British Columbia, Pollan reports, have found that trees in a forest can share resources. Specifically, firs and paper birch will use a web of mycorrhizal fungi to trade nutrients.
Now I look at the immense Douglas fir in the back yard, and the tall paper birch across the alley, and wonder if they’re communicating. And what will the neighbors say? Unfortunately, I won’t know; as a mere human, I can’t sense the process.
Waging war with chemistry: I’ve long noticed that some plants don’t like each other and will avoid being in the same area. And indeed, “Plants perceive competitors and grow away from them,” Rick Karban, plant ecologist at UC Davis, is quoted as saying.
The most unpopular plant in our garden is the sword fern. Almost nothing grows in the shadow of its spore-laden fronds. It has perfected dislikability over eons, the modern fern dating back 145 to 360 million years—80 million years longer than dinosaurs.
Some time ago, I figured the older, dead fronds might make good weed barriers. I began stacking them in weedy areas, and it’s worked very well. As they break down, they form mulch that in turn nourishes other ferns to grow to giant sizes in our own little slice of Jurassic Park.
Plants can also draw upon thousands of chemical components to send out fragrances or odors, or even to change the taste of their leaves. Pollan writes of studies showing that when deer feed on acacia, the tree will change the taste of its leaves to something that repels the deer, or even make the leaves toxic.
This shifts my view of the balance between plant and animal as I watch the deer snacking in our local yards. They’ll eat a few leaves here, a few flowers there, and keep moving along. While I believe they’re smart enough not to threaten their food supply by overgrazing, I now also credit the plants with some active defense ability.
The most aggressive plants in my garden are sweet woodruff and peace lily—showing how inaptly both are named. I’ve had to curb their enthusiasm for strangling out fellow flora, and last year I got the bright idea of letting them fight off the buttercup that regularly invades from the back alley.
It was a tense summer in the test patch beneath a forsythia, where I encouraged the three to meet and fight it out. The woodruff came out on top, its ally the peace lily stood its ground, and the buttercup has barely dared to show up again. But will it remember this season, on this battlefield?
Making memories: As I read about experiments suggesting that some plants may form memories, my human brain scoffs that surely a convoluted cortex is needed for that. But scientists—including some in other areas than botany—are looking into systems of distributed intelligence and swarm intelligence. They often use our humans’ computer-based internet as a metaphor.
Perhaps memory, or learned adaptation, can be stored without a central brain. I like imagining, as I pull weeds, that maybe their kin will know not to come back. Actually, this happened with a terribly invasive knapweed, or knotweed. We had to dig its woody root system out of the garden over several seasons of ferocious battle. Then it disappeared. Maybe its roots left chemical traces saying this soil wasn’t a friendly place.
Living on light: I learned about photosynthesis ages ago, probably in grade school. But each fall, as we stack hundreds of pounds of trimmed vines, branches, pods, stems, and leaves, I’m struck that this vast bulk—truckloads full—barely reduces the volume of garden soil. You’d think an equal amount of dirt would disappear to account for all of this—but only a tiny bit does.
And this is the wonder of plants, Pollan reminds the reader.
As I head out for another few hours in the garden, I know my sense of wellbeing will grow and time will slide by to almost disappearing. Even if all I’m doing is lying in the hammock and staring up through tree branches, the plants are working to slow me down. Maybe they intend this, so I will appreciate them more.
After reading about their abilities as described by scientists, I continue to muse about my own plants and wonder. More accurately, I muse in wonder.
