Plants can see, hear, talk, smell, taste, feel, communicate and remember. Plants have more sense receptors than people! Tomatoes can sense an approaching cyclone three days in advance, and if plants have a “headache” they produce their own aspirin… Research is constantly unearthing amazing new information!
As you start reading this article, say the two following words aloud at least once: “brother tree”. It’s a very simple experiment: do you feel stupid saying this? If so, I hope this article will change that.
Like all plants, trees are descendants of the same life forms that also stood at the head of our line of ancestors—and we should never forget it. For many decades now, it has been the fashion to busy ourselves with protecting the environment, yet the necessity of plant protection only penetrated our consciousness a comparatively short time ago. Why? Well, plants don’t scream in pain; they don’t run away—in our eyes, plants behave almost as if they were dead.
Yet one thing is clear: plants are living beings just like animals and people. And that’s not all: “Plants have capacities that we can hardly imagine,” says Anthony Trewavas, Professor of Cell and Molecular Biology at the University of Edinburgh. The 70-year-old Scot—a member of the Royal Society, the oldest scientific society in Great Britain—is the head of a vanguard of plant physiologists, molecular biologists, ecologists and agricultural researchers who are shaking the foundations of biology. These scientists working in the relatively new field of plant neurobiology are tearing down the barriers that have existed until now between the animal and plant kingdoms.
Researchers have discovered mechanisms in plants that are comparable with neural information processing systems in animals. They address what most of their colleagues dare not consider: intelligence, memory and a plant’s ability to learn. These scientists base their work on the most modern research methods, and their results reveal plant characteristics that are reminiscent of fantasy worlds such as that of Tolkien.
Plants can see, can hear, speak, smell, taste, feel, communicate and remember; they have more sensory receptors than people! Our green friends constantly check their environment according to twenty different factors including light, moisture, soil condition, gravity and electrical and magnetic fields. The latter is used for orientation—very similar to birds.
Plants even have the most sophisticated capacities for intelligence: “They have the capacity to predict the future,” explains Anthony Trewavas. The researcher has also proved that supposedly primitive plants even carry out cellular mathematics and Euclidean geometric calculations.
A growing group of botanists has joined a guild that has become renowned for its observation of animals such as greylag geese: they are called ethologists. These biologists talk about the “search for a partner,” the “jealousy” and the “social intelligence” of their green research objects.
Does the wall flower need love, too? Is a plant capable of leaning happily towards the watering can—and can a bush shrink away from the garden shears?
“Nothing in the plant world is too crazy to be true,” says Professor Dietmar Volkmann from the Institute for Cellular and Molecular Biology at the University of Bonn. “We have always underestimated plants—and still do today.” Only the Native Americans always seem to have known it, teaching their children: “Trees are animals without feet”.
The newest scientific findings just express it differently.
Plants can see: They have billions of eyes; in fact, their entire green surface is a unique sight organ. The plants’ optical cells are able to perceive more wave lengths than our eyes. The stilt palm (socratea exorrhiza) actually walks out of the shadow of larger trees by forming stilt roots and rotting off others; it is always in search of the best location. “That this is intentional behaviour is very clear,” says Trewavas, who has already observed this behaviour in plant shoots. “Even the shoot itself builds a three-dimensional picture. Growth and leaf angle are arranged in such a way that the young plant gets as much light as possible. Modern cell biology has shown that such reactions are not predetermined.1 They require a flexible and adaptive behaviour i.e. intelligent behaviour.”
Plants can hear: Music promotes their health. “Our language or even music is strong enough to stimulate plant membranes,” says biologist Stefano Mancuso after almost ten-year field and laboratory studies. “The tone frequencies can have a comprehensive influence on growth, even if some scientists don’t want to hear it.”
Of course, plants have no ears, but on a molecular level they have very similar tools by which they perceive different frequencies. Each cell has a membrane that is more sensitive than the human ear, something which has since been confirmed several times: Chinese scientists managed to prove that a lower frequency sound increases enzyme activity and stimulates the cell membrane fluid.
South Korean researchers lead by Professor Jeong Mi Jeong from the National Institute for Agricultural Biotechnology in Suwon treated rice plants with classical music pieces such as Beethoven’s Moonlight Sonata through ultrasound, while simultaneously investigating gene activities. They discovered that plant genes rbcS and Ald, presumed responsible for growth, became especially active at very specific frequencies. Researcher Mi Jeong also managed to attach tone-sensitive gene switches (promoters) to other genes, which resulted in the fact that these too were then able to react to tones. This is very promising, and may be of great practical use; for example, farmers in the future would be able to turn specific plants genes on and off by producing sound waves at will. This method could be targeted to genes that cause blooming, for example and would be cheaper and more environmentally friendly than any other technology.
American farmer Roy McClurg also regularly uses ultrasound on his forty-acre orange plantation in Gerber Grove in Florida—though he doesn’t supply it with music. Instead, the loudspeakers blast a sound that to humans sounds like a veritable choir of crickets. Birds, however, are fully acquainted with these harmonies as a song and can thus be lured to the “sound farm” in their multitudes. Unlike the other local citrus farmers who use pesticides, McClurg only ever exposes his plants to the loud twittering sound to increase growth, yield and quality. And, as it turns out, his oranges almost reach the size of small grapefruits, contain double the Vitamin C content and increase the plantation yield by around 30 percent.
Don Carlson, developer of the “Sonic Bloom” method, can accelerate the seed’s germination period. “Sound,” he says, “is just as important for plants as the process we call photosynthesis”. If this is true, then the tweets and chirrups of blackbirds, thrushes, finches and starlings contribute to the growth and development of all nature.
Plants can speak: “Plants have a lot to say,” says Professor Wilhelm Boland, a biochemist who understands the plants’ language, this “language” being chemistry. And their “words“ are fleeting substances spread by the wind, by which a plant can communicate just as an animal communicates by calls.
“For me, this is the most sophisticated phenomenon. This type of scent communication happens very quickly, within a matter of minutes. It is the flora’s Information Highway,” enthuses the chief of the Department for Bioorganic Chemistry at the Max Planck Institute in Jena, Germany. And what do our green friends chat about? “Plants mostly converse about predator attacks,” explains Boland.
Through this type of communication, acacias in South Africa were able to inform each other of 3,000 greedy attacking Kudus—and react to the warning. Subsequently, the animals were literally “murdered“… Acacia leaves are in fact the favourite food of the Great Kudu (a type of African antelope), and a post-mortem revealed that they had chewed down substantial amounts of the leaves and died with their bellies full. How could that be possible? Zoologist Wouter van Hoven discovered the solution to the riddle: acacias keep enemies at bay by drastically increasing the concentration of the bitter material tannin in their leaves.
This is triggered when the leaves are shaken. So as soon as the first acacia is nibbled, the tannic acid production in the leaves rises and a very specific fragrance is transpired: ethyl. This gas is like a dumb scream that sets the neighbouring trees on guard, at which point they too increase the amount of the tannic acid in their leaves. At some point in their evolution, the Kudus became aware of this team alarm signal and began to wander slyly from tree to tree. They began to eat quickly and briefly, and walk to the next tree against the wind!
Yet on this occasion, the animals were not able to sneak far enough away; in fact, they had been held in a large enclosure. There they ate far longer at one particular tree than they would have done in the wild; thus they stuffed their stomachs with leaves that had a high content of tannin. Kudus are unable to digest such poisonous greenery in large quantities, and so it eventually kills them.
This incident shows that plants can not only communicate, they can also smell. They perceive messenger substances even in slightest concentrations, at which even the best gauges fail.
Plants can taste: A plant’s root tip is more sensitive than any epicure’s tongue. The molecular biologist Frantisek Baluska from Bonn, Germany, discovered that the areas near the root tip play a very special role in intelligence capabilities. On his computer screen, he displays a rye plant just four months old. Its huge root system spans about 1,000 square meters and has an estimated number of 13 million roots; its total length is approximately 600 km. And if you also count the approximately 14 billion little root hairs, this results in a length of 10,600 km—the approximate distance pole to pole.
Every single one of the myriad of root branches has a zone that assumes functions similar to the brain: all together it forms the plant’s communication centre. An underground neural network as big as the world wide web—a true “wood wide web”, so to speak!
Plants can feel: Some plants can even feel a “stroking” sensation from just 0.00025 milligrams of wool filament; something that we humans cannot feel against our skin. Not so long ago, people who wanted to lavish their cucumbers with loving caresses were seen as silly idiots, but the days when we laughed at such people are well and truly over. These days all you can do is say: Keep at it! Plants grow better if you stroke them regularly—and science knows why. “Touch activates certain plant genes,” explains Professor Volkmann. “These are called ‘touch genes’“. If they are activated, the plant growth changes—stalks become thicker.
This statement is easy to check: simply place two young bean plant seedlings in pots in an undisturbed place. Then massage one of the plant’s stalk sections above the small germ leaves between thumb and index finger four times daily for ten seconds for about a week. The difference in growth patterns is striking: the untouched plant skyrockets, while the stroked plant grows sturdy.
Plants have sensors that we lack: They even have a sense for the cardinal points: in strong sunlight the compass plant (silphium lacinatum) turns its vertically-directed leaves in a north-south-direction. Plants can also orient themselves towards electric and magnetic fields, like birds.
Plants can sense future events and predict the weather, for example. Tomatoes sense atmospheric cyclones three days in advance, and thicken their skin accordingly. And in scientific experiments the Indian herb arbus precatorius (Indian liquorice) proved to be a good “weather forecaster“ for storms and earthquakes.
Plants also seem to feel ill somehow. The researchers even speak of a “plant headache“ and the fact that plants may reach for some home-made medicine; something that we’re familiar with from our own medicine cabinets: aspirin. If a plant is attacked by bacteria, viruses or fungus, it discharges a chemical derivative of the plant hormone salicylic acid—in other words, the active component of aspirin!