In 2019, the world was buzzing(pun intended) over news that a study announced that some flowers will add more sugar content to their nectar if they sense a pollinator approaching. It has to do with the exact vibrations of the sound, which researchers discovered by playing different pitches of sound by flowers.
Blossoms exposed to silence as well as high-frequency and intermediate-frequency waves produced the baseline amount of sugar expected in their nectar. However, the blooms exposed to the beeās buzz and low-frequency sounds bumped their sugar content up 12 to 20 percent within three minutes of being exposed to the hum. In other words, when they āheardā a bee approaching, they sweetened their nectar.
That is almost completely it when it comes to plants and sounds. You might
Jason Daley, Smithsonian Magazine
So what is happening with the bees?
Since some of you are likely thinking about it, it is worth noting that the āplants grow better to classical musicā study is still currently being debated. However, it has been recently discovered that roots will bend towards sound (phonotropism) which actually explains why roots grow towards and wrap around water pipes.
You might argue that that is not hearing, it is just sensing vibrations, but that is exactly how humans hear as well.
When we hear something, we are sensing the vibrations in the air. The number of vibrations per second is known as the frequency, measured in Hertz (1 Hz = 1 vibration per second).
I am not implying plants āhearā in any way that could be described like we do, just that they notice vibrations from sound, and their cells are programed to react to that.
On a more creepy note, some plants even scream at a frequency we canāt hear when they are stressed. This could be a defense mechanism to keep pests away from the open wound, but it could also alert other plants, which would imply that the other plants notice the sound.
ā-stressed plants emit airborne sounds that can be recorded remotely, both in acoustic chambers and in greenhouses. We recorded ā¼65 dBSPL ultrasonic sounds 10 cm from tomato and tobacco plants, implying that these sounds could be detected by some organisms from up to several meters away.ā
As well as that, Cleve Backster ā the founder of the polygraph machine(a machine once used to see if people were lying) ā came up with the still debated theory that plants have āfeelings.ā
Backster came up with this theory after he attached the polygraph to a leaf and recorded reactions
The polygraph machine has since been disproven on humans and does not work for detecting lies, but the tests for plants made a resurgence thanks to the show Mythbusters. In the episode, they secluded a plant from noise and other distractions, attached the plant to the polygraph, and started testing the plant. When a leaf was hit by a person, the polygraph would move. Spikes increased with hits from fire extinguishers.
So while Mythbusters might not be the most trusted source, it would seem that plants do have an electrical reaction to pain. What this means, or if it means anything, is still controversial (though not nearly as controversial as Backsters claims that plants react to thoughts).
Given that plants do not have pain receptors, nerves, or a brain, they do not feel pain as we members of the animal kingdom understand it.
Similar to Backster, however, is the work by Neuroscientist Greg Gage.
He points out that plants feel and move with the sun, but also that the mimosa plant will curl up and close if touched. If the branch is tapped, the entire plant will go limp. This reaction shows on an EKG.
As well as that, he shows that the Venus fly trap(a quick will closing carnivorous plant), will count the seconds between the touching of trigger hairs within the trap. It will not close if the right amount of trigger hairs is not touched within the right amount of seconds. This is to conserve energy since it can take a whole day to open up again, and a trap can only open a handful of times before it dies.
Arabidopsis (a mustard plant commonly used in scientific studies) sends out electrical signals from leaf to leaf when it is being eaten by caterpillars or aphids, signals to ramp up its chemical defenses against herbivory.
So can plants hear and do they have feelings? The answer is a complicated yes.