Much of my childhood was spent deep in dialogue with a crew of non-sentient play pals. The top dogs in my pack of fixations were 1) magnets and 2) Venus flytraps. Proximity to either dialed in many an afternoon fugue state. Lounging now, in the temperate solarium of mid-adulthood, I find myself peering back through time’s foliage and wondering: why??
Sure, these earthly offerings exceeded the expectations of your garden-variety rock or plant. But both seemed to contain a potential far beyond their already-otherworldly capabilities. A magnet could be amplified to say, unhand an assailant of a weapon. If cultivated aggressively a Venus flytrap might consume far larger prey. For child me, these entities possessed dormant superpowers just waiting to be awoken.
And then I awoke this morning to find that for the first time in history, a group of mavericks out of Switzerland have detected a magnetic signal in a plant. Using a highly sensitive magnetometer, an interdisciplinary team of researchers have measured signals from a Venus flytrap of up to .5 picotesla. To make matters even more mind-blowing, this signal is roughly equivalent to the biomagnetic field strength of the human brain. The full report is here.
The findings shine a light on a whole new world of plant communications we never knew was there and paves the path for new approaches to diagnose and treat plant diseases. It’s a parade-worthy "I told you so" for champions of plant intelligence, and a new dawn for how we live in harmony with the green kingdom.
It all starts with biomagnetic signals
So, why does it matter that a plant has a detectable biomagnetic signal? Well, bioelectromagnetism is the amount of magnetic signal given off by a living thing, and it’s what the Swiss research team just measured. Biomagnetic signals originate from electrical fields generated by the physiological activity of a specific organ or tissue, such as the human brain.
The electrical field is driven by "Action Potentials," which is the difference between the resting and highest electric impulse of an entity in a given period of time. To give you an idea of what that looks like, where the line spikes at +30mV here, that’s the impulse of a human brain neuron. So the Action Potential here is 100mV:
Credit: Eric H. Chudler, Ph.D., University of Washington
One or many Action Potentials then contribute to a magnetic field.
So, for instance: A muscle contracts —> An electrical impulse is emitted —> An Action Potential hits —> An Electrical Field is generated —> A Magnetic Field is generated —> Both party together right on down the electromagnetic line.
Lots of things besides brains and plants give off magnetic fields. Here’s a comparative chart.
Some perspective on scale:
• A toaster’s magnetic field is 300,000 times more powerful than the human brain’s field
• The Earth’s magnetic field is 2,000 times more powerful than a toaster’s field
• And a fridge magnet is 58 times more powerful than the Earth’s field
That makes the signal we just detected from a Venus flytrap almost exactly a billion times weaker than a fridge magnet, and explains why plant signals have flown under our radar for so long.
In the 1960s, though, a new class of magnetic field sensor showed up on the scene. It could detect weak biomagnetic fields, from a human brain and potentially even a plant. Behold…
The Superconducting Quantum Interference Device (SQUID)
SQUIDs are sensitive magnetometers used to measure extremely subtle fluxes in the magnetic field. The magneto-sensitivity of SQUIDs gives them extraordinary powers for recognizing the world around us. They represent the closest our technology has come to being psychic.
The hero feature of a SQUID is the Josephson junction. It's composed of two superconductors separated by a super-thin insulating material, usually copper.
The device gets inserted into a -346 Fahrenheit bath (usually nitrogen or helium). This cools the SQUID down to superconducting temperatures. The bath sits in a lead container, both of which also shield the SQUID from other magnetic fields which, in their ubiquity, are a real nuisance for detecting subtle magnetic field changes.
Any electrons passing through the junction demonstrate quantum interference, which then gets run through an algorithm and spits out a magnetic field reading.
The list of applications for SQUIDs in defense, geophysics, space exploration and beyond is currently exploding with possibilities even decades after the device first showed up on the scene.
To give a sense of the power of the SQUID: mining company Outer-Rim Developments in Australia used a SQUID to measure ground surface electrical connectivity, successfully identifying a silver deposit two kilometers below the Earth’s crust. It’s the largest found anywhere ever, worth about $2 billion.
In 2017, researchers at the Shanghai Institute of Microsystem and Information Technology also developed a SQUID array that can detect a submarine magnetic field from an outlandish six kilometers away. It can also effectively time travel, identifying a submarine’s magnetized particle "wake" as much as two weeks after the fact.
And now, SQUIDs have initiated a potential quantum shift in our relationship with plants.
The Venus flytrap boasts three trigger hairs that serve as mechanosensors. When a prey insect touches a trigger hair, an Action Potential is generated and travels along both trap lobes. If a second touch-induced Action Potential is fired within 30 seconds, the energy stored in the open trap is released and the capture organ closes. This is the plant-insect equivalent of a repeat offender. Imprisonment ensues.
Crucial to making these findings was the fact that this electrical activity doesn’t carry into the stalk of traps, which allowed the researchers to isolate the lobe by slicing it from the rest of the plant. Biologically intact, it was then placed on to a sensor.
The size and biology of a plant cell pose all sorts of regional challenges for magnetic field sensing. To tackle the challenge the researchers needed:
• A diverse team from Johannes Gutenberg University Mainz (JGU), the Helmholtz Institute Mainz (HIM), the Biocenter of Julius-Maximilians-Universität of Würzburg (JMU), and the Physikalisch-Technische Bundesanstalt (PTB) in Berlin, Germany's national meteorology institute.
• Heat stimulation to trigger Action Potentials in the fly trap because thermal energy emits zero background noise.
• A custom sensor consisting of a vapor-filled glass cell that further suppressed noise.
• Additional sensors placed around the room to differentiate any plant signals from environmental noise.
• An optically pumped magnetometer, as opposed to cryogenic cooling, which can be miniaturized and also prevented the plant matter from freezing.
The readings returned pretty much identical results four times in a row.
The discovery is as huge for biomagnetism in plants as it is for electro-physiology in general. We now have proof of a pathway for long-distance signal propagation between plant cells. Talk amongst your cells.
Both signal a new era of understanding plant systems we are only just coming to grips with.
The report’s introduction ponders, “in the future, magnetometry may be used to study long-distance electrical signaling in a variety of plant species, and to develop noninvasive diagnostics of plant stress and disease.”
With the help of this current research, crops could be scanned for temperature shifts, chemical changes, or pests without having to damage the plants themselves.
But that’s tomorrow, and we are unfortunately fastened firmly to today.
To get a sense of the bigger picture, I spoke with Greg Crutsinger, Director of Applied Research at GeoAcuity. Motherboard highlighted his work in turning consumer drones into high-precision crop monitoring tools a few years ago. His efforts allow farmers to rapidly and repeatedly monitor the health of their plants from the sky, identifying which areas of land need more water or fertilizer.
Our conversation exhibited a common refrain. Before widespread application of this new sensory technology, our species needs to first open our minds to a hidden electromagnetic network.
“We’re so biased by human eyes," Crutsinger said. "Yesterday I was going through some of the microsatellites that are going to scan the Earth with radar. We’re looking at different wavelengths and how they can measure moisture in plants by how deep the radar penetrates into corn. I look at the world in different spectrums now and different scales. This is similar. It’s just at this fine scale we haven’t thought of yet.”
Beyond the perceptual, there are daunting practical considerations. Lab settings provide a convenient vacuum where these almost-imperceptible magnetic fields can be measured without getting drowned out. Greg was clear about the challenges of packing up this gear and heading out into the world.
“Typically what we’re thinking about when we’re in plant magnetic spectrums is imagery and light: how are they interacting with wavelengths beyond the scope of the human eye? We can pretty easily use different sensors for that," he explained. "The challenge is mechanical, trying to measure it, and understanding what it means at such a fine level.”
Obstacles aside, new advances contain huge promise for understanding the staggering amount of data we’ve been looking past.
“I have a drone that I just picked up from Best Buy and did a 3D model with over lunch. The potential is moving very quickly to miniaturize a lot of these capabilities,” said Crutsinger. “As we advance the sensitivity of these tools and more people start using them and not just two labs in the world, I think they’ll start becoming more commonplace in terms of adoption.”
Perhaps our best next step is looking at how other species interact with these magnetic fields. Since these fields exist, they may serve some practical purpose. “Plants and insects have co-evolved for millions of years,” explained Crutsinger. “The trap is getting prey. But insects could leverage that to their own benefit as well. They’re super sensitive and they have antennas. How might they cue in on the magnetic fields of the plant. It’s just also something we have to pay attention to.”
It’s at once discouraging and hopeful to consider the vastness of what we can’t perceive. Perhaps human consciousness is not so much defined by knowing that we know but by acknowledging what we do not.
Either way, it’s a heck of a day for plant nerds.
Thobey Campion is the former Publisher of Motherboard. You can subscribe to his Substack here.