Plant Intelligence

For thousands of years, Man considered himself the only sentient being in the universe, the only one capable of higher thought, understanding, and language and communication.

We now know that isn’t true. Higher primates, such as gorillas and chimps, are certainly capable of learning not only their own forms of communication, but American Sign Language as well. Dogs, it turns out, are capable of understanding human language at the level of a three year old human child, with some breeds (like German Shepherds) able to differentiate up to a thousand different words. We know that octopi can perform complex tasks (of their own planning, nonetheless), recognize people, and have a functional IQ of about 40. Dolphins and whales have complex languages and not only communicate, but show empathy.

Hence, many people choose not to eat animals, and dine only on plants.

But what about plants? What about their feelings?

Plants? What does a plant know? Corn has ears, but that doesn’t mean it’s listening.

Turns out, plants know more than you think. Plants have been caught communicating in numerous ways, understand when danger is near, and sympathize with other plants.

Yes, really.

This communication is known as phytosemiotics. One way is through chemical signals. A wounded plant will give off a volatile chemical compound (something you can smell) that other plants can sense. The receiving plant can then roll up its leaves or lean away. That wonderful fresh-cut grass smell we love in the summer? Yeah, that’s a hundred thousand blades of grass screaming in agony and warning other plants to beware that something is damaging them. Plants also communicate through ultrasonics – noises above our hearing range but which can be detected and recorded on audio equipment (ultrasonic vibration of 20–105 kHz). Some of this may be due to tiny air bubbles being released due to chemicals triggered during stress. Trees, it turns out, communicate under the soil as well, using certain types of fungi in the dirt to communicate through their roots. Are they discussing algebra? No. But they can tell each other about dangers, or fresh rain, or the pain of bark beetles, and other plants can ‘arm’ themselves accordingly. Just the sound of insects chewing can cause plants to release chemicals that deter insects (caffeine, by the way, exists in plants as a natural insect repellent).

Perhaps the Druids were on to something, thanking plants for sacrificing their leaves.

If that’s not weird enough, plants – even those without ears – apparently respond to music. Sure, houseplant lovers will tell you they’ve always known this, but numerous studies have turned up actual results. As early as 1962, studies showed that plants exposed to classical music had a 20% growth increase and a 72% increase in biomass over controls. Violins gave the best result. This was repeated by a Canadian researcher, with 66% increase in wheat yields using Bach’s violin sonatas. Duckweed, a water plant, exposed to Bandri’s Purple Butterfly, five hours a day for seven days at 60-70 decibels, showed a 10% increase in leaf growth and a slightly higher protein content compared to silent plants. Roses love violin music. Heavy metal tends to induce stress. Devendra Varol of the Institute of Integrated Study in India found that plants can not only distinguish between genres of music, but also nature sounds and traffic noises.

Oh, those poor weeds on the highway!

And while you laugh and scoff, know that in 2004 the TV show MythBusters attempted similar experiments in seven greenhouses. In their experience, Death Metal produced the best growth, second was classical, and third was positive spoken words. The silent greenhouse had the worst growth.

How can this possibly be?

The best theory is that the vibration of music may aid plants in transporting their nutrients more efficiently, shaking things through faster.