Finding the Light
Non-fiction - by Peter Jekel
The clearest way into the Universe is through a forest wilderness. John Muir
The next time you cut your lawn, take a moment and smell the air and you will notice that distinctive odour of freshly cut grass. Most people like the smell except for those who might suffer from some sort of hay fever. What if you were told that that smell could actually be a “scream” for help by a plant? Would you believe it? Likely not. However, new research is showing us that there is nothing ordinary about our relatively stationary fellow lifeforms, the plants. They are very intimate with their environment. The question now is whether or not they are aware.
Plants are one of the major lifeform kingdoms of the Earth, known as Plantae. They are predominately multicellular organisms which includes all flowering plants, the conifers or evergreens, the gymnosperms, mosses, hornworts and liverworts; the kingdom also contains many species of single-celled algae. As a group, they obtain most of their energy through a photochemical reaction, known as photosynthesis, that happens in organelles known as chloroplasts, found in their cells. Chloroplasts are likely the result of an ancient symbiosis between the ancient cyanobacteria (blue-green algae) and the first plant cells; cyanobacteria, though not true plants but a form of bacteria, are able to photosynthesize.
There are some plants that have, however, given up the ability to photosynthesize and instead are parasitic or mycotrophic (mycotrophic is a symbiosis with a fungal species). As we will see later on the mycotrophic characteristic might be somewhat misleading now since all plants seem to have a symbiotic relationship with fungi. One interesting type of fungus (Fusarium xyrophilium) appears to be so enamoured with plants that it actually creates “faux flowers;” that is, it blocks the creation of a plant’s own blooms, instead creating exact mimics of its own thus allowing for would-be pollinators, thinking that they are landing on a true flower, to go about spreading the fungal spores. An interesting fact about fungi is that they themselves were at one time classed as plants that do not photosynthesize but genetic studies have shown that the likely ancestor of fungal species puts them in a grouping more closely aligned with animals. As a group, all plants do reproduce by means of seeds or spores (algae) through a combination of asexual and sexual reproduction.
In terms of structure, multicellular plants all have three basic parts, the leaf which is the organ of the plant that captures the energy from sunlight and carbon dioxide from the air to allow for photosynthesis to happen. There is generally a stem that connects the leaves to the root system; the stem has a vascular system to support this connectivity allowing for the transfer of food and water around the plant allowing it to grow and thrive. Then there are the roots that help the plant stay put on the Earth while gathering the essential water and minerals from the soil essential to their growth.
As a group, plants make up more than eighty percent of the biomass of the planet, occupying most ecological niches on the planet. Some authors have taken the dominance of plant lifeforms into account in their stories. Greener Than You Think is a classic novel by Ward Moore where Bermuda grass runs amok destroying all other lifeform competition. Seed by D. G. Leigh is about an alien invasion of the Earth by kilometer tall trees with growing and interconnecting branches that gradually block the light from the Sun, eventually obstructing its life-giving rays entirely, plunging the planet into permanent darkness.
Alan Dean Foster created a fictional world with plants being a dominant lifeform. In his Midworld a planet is invaded by humans with plans to destroy the globe-spanning forest with heights reaching almost a kilometer into the skies. Peter Hamilton, known for his grand scale science fiction describes in his Great North Road, a planet that has a complex ecosystem made up only of plants, no animals at all.
Perhaps one of the most bizarre alien plants has been created by Larry Niven with his The Integral Trees. The tale takes place on a gas giant that orbits a neutron star that maintains its integrity as a loose torus of gas. All life, including plants, on this weird world live in a perpetual free fall. Due to their free fall existence the plants are fragile since weight support is not an issue allowing them to grow up to a hundred kilometers in length topped by a green tuft of leaves. Niven also wrote of a Tree-of-Life in his Known Space short stories and novels. The plant is an important transitionary stage for a lifeform known as a Protector. Though not in a novel or story, it could serve as the basis of one. Physicist Freeman Dyson described a plant, known as the Dyson tree, that could theoretically exist on a comet. Another bizarre alien plant can be found in Terry Pratchett’s Discworld series. Due to a bizarre twist in their genetics that includes a time dimension, the plant actually grows before the seed even germinates.
It does not take place on an alien world but on an Earth of the far future. Brian Aldiss’ Hothouse describes the Earth as being tidally locked with the enlarged Sun and attached by webs of giant spider-like plants, to the more-distant Moon (the Moon, is incidentally, slowly moving away at a velocity of 3.8 centimeters per year from the Earth). Plants in this future Earth abound with the increased light and heat and actually have filled many of the ecological niches formerly occupied by animals; of the animal kingdom only descendants of social insects and small groups of humans still survive.
Outside of the plants of science fiction, plants are normally looked upon as simple and therefore often garner no more than a fleeting thought from a passing onlooker, that is, unless they are gazing up the heights of a redwood pine, marvelling at the age of the cliffside cedars hanging on the edge of the Niagara Escarpment in southern Ontario and happen to be many hundreds of years old, tasting the sweetness of maple syrup drawn from the sap of hardwood trees in northern deciduous forests, angered by a lawn full of dandelion weeds or just awestruck by a carefully manicured garden. In fact, there is term known as “plant blindness” that is a cognitive bias amongst animals, especially humans, to underestimate the plants that dominate life on Earth. The truth is that there is far more with respect to plants than first meets the eye. Plants are sophisticated lifeforms and recent evidence shows that they are really far more complex than anything that we realized before.
Nobody suggests that plants feel like animals do, but they do show a remarkable awareness of their environment. The challenge now is for researchers to demonstrate that plants might actually be intelligent in their response to changes in their environments; it is a relatively new field of study known as plant neurobiology. If plants are indeed intelligent which, if proved, would result in not only a new revolution in biology, but also a rethinking of human society altogether. Imagine what a vegan would think about their plant-based diet should plants be classed as intelligent, or even “feel” pain. Many scientists still consider the study somewhat controversial however, since there is the obvious known fact that plants don’t have brains much less the neurons that make up the nervous system of animals.
In spite of the controversy, there is the International Laboratory of Plant Neurobiology (LINV) in Florence, Italy that argues that having a brain is not a prerequisite for intelligence. Researchers at the facility believe that plants are actually conscious, basing their beliefs on the concept that consciousness is based on an awareness of one’s surroundings, one’s own existence, and the passing of time—all traits that plants seem to possess.
There was a best-selling book about plants published in 1973 called The Secret Life of Plants, that suggested that plants have extrasensory perception (ESP) as well. This book, though entertaining, probably set the study of plant behavior back as it attracted a fringe element by veering into the supernatural; this often will deter serious researchers from venturing into the field of study. The authors based their thoughts about plant ESP on work of a CIA operative named Cleve Backster who in 1966 hooked up a galvanometer to the leaf of a houseplant in his office. According to Backster when he imagined burning the plant, the needle of the galvanometer moved rapidly. A first question with respect to this should likely be what would possess someone sitting in an office to imagine burning a plant? In spite of the weird thought, Backster’s conclusion of this observation was that the plant was actually reading his mind. He and others then hooked up the machines to other plants to find similar reactions. The powers of the plants went a step further. In another experiment by Backster, he found that a plant that witnessed the “murder” of another plant by a person could figure out the culprit from a lineup of suspects, with a surge of electrical activity when the “murderer” was shown. Plants also were found to possess extreme empathy even beyond that of their own species. They reacted with extreme electrical activity to shrimp being placed into boiling water or an egg being dropped on the floor. Interesting results but none were reproducible in future experiments, essential to the pursuit of scientific truth.
There are, though, far more recent behaviors of plants that have been scientifically studied and that put plants on a level far higher than what were once thought as being the simple, stationary lifeforms that grace our gardens, fields, forests and greenhouses. Plants communicate with one another through a number of means. One is through electrical signals that are transported through the phloem, the cells of the vascular system of plants. As the plant continues its growth, the phloem cells become more and more interconnected, not unlike the neurons of an animal brain. Plants respond to various environmental stimuli whether it be an insect attack, a change in temperature or light by eliciting electrical signals. The “memory” is then stored in the plant’s phloem cells to allow it to respond better to similar stimuli in the future. How such a “memory” is stored is not known; there is some physiology at play that botanists do not fully understand. To confound things further, we find that plants do possess chemical neurotransmitters such as glutamate, dopamine and serotonin that are essential to the functioning of the nervous system in animals. Is the presence of these chemicals a part of some ancient evolutionary leftover from before the plant and animal kingdoms differentiated from one another, or is it involved in some sort of information processing in plants? We just don’t know.
The Hyperion series by Dan Simmons, describes large electrified trees called Tesla trees, on his planet Hyperion that store electricity during certain seasons only to release it in huge arcs of lightning from their crowns. This action burns all around it providing the plants with fertilizer to further its growth.
Plants also have a distinctive aroma whether it be a spice, herb, flower, vegetable or tree. These odours are created by chemicals known as terpenoids. The terpenoids are important in the communication network between plants themselves but also with insects, fungi, microbes, birds and mammals. For example, they will either act as an attractant for a pollinating bee or a repellant for an invasion of aphids. At least one author, Karen Hugg, took advantage of this quality of plant communication to write The Forgetting Flower. The plant is not only beautiful but when it blooms, it emits a chemical that when inhaled causes the person to forget.
Plants will also communicate stress to other plants via their roots to unstressed plants, to “warn” them of the stressing event. In one study with ordinary garden peas (Pisum sativum) it was shown that a pea plant that was being stressed with drought-like conditions was planted on both sides with unstressed plants, in other words they were watered. The plants were able to sense and respond to stressor cues being sent out by the drought-stressed plant. The neighboring plants responded by stomatal closure (response of plants to drought-like conditions, stomata being tiny pores in the stems and leaves of plants).
One remarkable feature has been found in the Venus flytrap, a carnivorous plant of the southeastern bogs of the United States. Carnivorous plants are made up of a number of species across the globe ranging from active plants such as the Venus fly trap, bladderworts and sundews, but also the passive pitcher plants that trap insects and other small animals in their cup-like leaves filled with water. The downward pointing hairs lining up the inside of the leaf cup of the pitcher plant prevents an unwary insect that enters the trap from escaping. Exhausted from its attempts to escape, the animal eventually falls into the pool of water and drowns; the plant then starts the digestion process. Carnivorous plants evolved their carnivory appetites to subsidize a nitrogen-poor environment in which they find themselves.
There were many early stories of plants that would further their nutritional needs by killing and eating a human; the stories were written as if they were fact. The stories peaked in their popularity in the mid-1800s when Europeans were actively exploring the unknown jungle vistas of South America and Africa. We can be rest assured that most of the stories are second-hand in nature, embellishing an already tall tale from one of the intrepid explorers. Edmund Spencer wrote a report that appeared in the April 1874 New York World, that described the Madagascar Tree that would engulf a human victim in its leafy tentacled folds. His report was based on an account from a German explorer, Karl Leche who encountered a human death of the Mkodo tribe of Madagascar by such a plant. The plant allegedly looked a lot like a pineapple that collected sweet nectar in a pool created by the arrangement of the leaves. When a woman drank this liquid, the tendrils grabbed her and the leaves closed in starting its gruesome consumption. Leche reported then seeing a gory blood mixture that circulated in the plant’s stem. Fourteen years later, the “true” story was betrayed as being fiction. Another tall tale is Phil Robinson’s 1881 Under the Pukah about the Nubian tree of northeastern Africa. The author’s uncle told the tale of a plant with large waxlike flowers and fruit with leaves that would open and close like a hand; the “eye-witness” account describes a boy trapped in the tree’s leaves after having pursued a deer into a thicket. J. W. Buel, wrote in 1887 Sea and Land that describes a plant of Central America that grabs any victim unfortunate enough to venture too close to its tentacles. Allegedly, the plant also makes a hissing sound when a victim is close by, hence its name, ya-te-veo which is a Spanish translation of “I see you.” Once captured, the victim is squeezed dry of its bodily fluids with only a dry husk remaining which the plant then discards, setting the trap for the next victim. He also describes a vegetable Minotaur. This plant has a thick short truck topped with giant, flexible spines edged with barbs. The spines grow downward into the surrounding ground. If someone ventures too close to this bizarre plant entering the circle created by the downward-pointing deadly spines, the spines rise up and entwine the unfortunate victim drawing them to their horrific doom. Both stories of human-eating plants are also second-hand and were not observed by Buel himself. Though all tales of human-eating plants are dismissed today as tall tales, they did feed the fear of the unknown for many readers for many years.
There is one tale that might make the reader squeamish though. It is not directly about a plant consuming a person however, but rather the ingenuity of humans to use the habits of a plant to provide excruciating pain to a human victim. In 1821, during the Thai invasion of Kedah in Malaya, soldiers observed a form of execution by a mangrove (Nypa fruticans), used on captives; a mangrove will grow up to a meter per year. It worked by placing an immobile captive on a growing plant with the person slowly being impaled as it grew. The tale may not be so far-fetched either and actually may be a case of mistaken plant identity. There are some species of bamboo (Bambuseae sp) that grow up to a meter a day and could pierce a human body that is hung in its growing path; this has been demonstrated experimentally with a ballistic gelatin being used rather than a human victim.
Speculative fiction writers took advantage of this fascination with human-eating plants with fictional tales of their own. Perhaps the first such tale is H. G. Wells’ The Flowering of a Strange Orchid about a shy botanist who is saved by his housekeeper from his blood-sucking orchid. Another early tale is Howard Caris’ Professor Jonkin’s Cannibal Plant, about a plant that enjoys a good steak but then decides to expand its dietary needs by attempting to eat the professor who is saved by a friend who injects the treacherous plant with chloroform. Specimen 313, by Jeff Strand is about another meat-eating plant, named Max, that lives in a greenhouse with a mad scientist as its keeper. Perhaps the most famous human-eating plant is found in a musical by American playwright Howard Ashman, entitled Little Shop of Horrors, about a plant named Audrey, owned by an introverted botanist that eventually turns the tables on him. The Plants by Kenneth McKenney takes place in the fictional village of Branding that is filled with thriving gardens; however, the people are not so lucky as they are being mutilated by the plants. Clark Ashton Smith’s The Seed from the Sepulchre, is a horror story about people not being consumed by plants but instead ‘fusing’ with them to create a plant/animal hybrid. Many of the early short stories of speculative fiction with carnivorous plants can be found in Arboris Mysterius: Stories of the Uncanny and Undescribed from the Botanical Kingdom edited by Chad Arment.
Jeffrey Lord, took the idea of human-eating plants a step further and created a whole forest of them in his fantastical Killer Plants of Binaark. Robert Silverberg also wrote a tale of trees early in his career, his The Fangs of Trees. The story follows the ecological movement of the 1960s with a main character even “hugging a tree.” The dimension that Silverberg added (he could have just as easily have told his tale with ordinary trees but what fun would that be?) was that his trees turned out to be sentient as well as meat-eaters.
Back to the Venus flytrap. It appears to have the ability to count up to five. Sensitive hairs line the inside of the jaw-like leaves of the plant and are sensitive to touch. If a flytrap hair is touched once, the plant remains idle. If a hair is subsequently touched again within twenty seconds of the first touch, the leaves snaps shut trapping the unwary insect. The prey will struggle in the trap triggering a third touch of the hair with no response by the plant. A fourth time the hair is stimulated by the struggling victim and again no response. Only when a fifth hair is touched do the digestive juices of the plant begin to flow. Is this evidence of intelligence? It does definitely demonstrate a form of “memory” to prevent a costly use of resources to attack prey by avoiding false starts; a strong breeze could otherwise be a form of stimulus similar to an insect but offer no substantive return.
Some botanists have proposed that plants actually do “learn” from experience and store the learning as a “memory” to guide future behaviour. One famous experiment that was done at the University of Missouri by a researcher who played the recording of a caterpillar chewing on the leaves to a leafy plant. It was well-known at the time of the experiment, that when plant leaves are chewed upon, that plants do produce volatile chemicals designed to deter the caterpillar attack. In the experiment, the mere sound of the leaf-chewing elicited the same reaction in the leafy plant. In another study, it has been found that Neptune seagrass, Posidonia oceanica from the Mediterranean is sensitive to noise pollution. In the experiment,, the plant was exposed to two hours of noise which in turn damaged the plant’s ability to store energy and detect gravity (essential for growth).The experiments would seem to indicate that plants can also “hear.”
In another experiment, researchers repeatedly stimulated a sensitive plant (Mimosa pudica) which curls up its leaves when touched; it makes a good houseplant companion and is a good conservation piece. When the researchers initiated a number of false alarms the plant changed its response and no longer curled its leaves up when touched by the researchers. According to the researchers the plant had changed its response and created a “memory” that lasted for months longer than a memory in many animal studies.
Plants also are able to communicate with the world around them. What makes the communication very interesting is that the plants not only communicate with their own species but with other species as well, far more than most animals. In one experiment, leaves were being clipped off of sagebrush plants (Artemsia sp.) which caused a chemical reaction in the plant being clipped but also by other plants in the same area. Those sagebrush that were most closely related genetically to the original clipped plant had a stronger reaction than those that were not as closely related.
An experiment to display the communication prowess of plants with other species is demonstrated in an experiment with corn (Zea sp.). In the experiment corn that was being attacked by caterpillar emitted a scent that attracted parasitic wasps to take care of the caterpillars. These wasps lay an egg inside the caterpillar while at the same time immobilizing it, but not killing it. When the egg hatches, the larval wasp then commences to consume its living home.
Insects are but one lifeform that plants communicate with. Fungi are another lifeform that plants not only communicate with, but have a true symbiotic and in some cases a parasitic relationship. Blight is a fungal disease of many plants including tomatoes; here a fungal species is acting as a parasite. In one experiment, two tomato plants were planted together in pots and then wrapped tightly in a plastic wrap so that the only connection between them was through their roots. The researcher injected blight into one plant and then sixty-five hours later infected the second plant. The second plant was found to be less likely to contract blight, having likely gained information about the disease through the root network from the previously infected plant, thus allowing it to mount a defense. Information through the root network is actually being exchanged through mycelia which are the vegetative part of fungi. The plants provide the fungi with essential carbohydrates and in turn, the plant has a sophisticated communication system. There is some research that indicates that an entire forest can be interconnected with these mycelial networks. Plants that have had their mycelial network removed are found to be more vulnerable to insect attack, for example, than those that are able to connect with one another through this communication mechanism.
In an interesting piece of research at the University of British Columbia, two types of trees, the Douglas fir and the paper birch, communicate with one another through the mycelial network, which is an interconnectivity of the plant roots through means of a fungal species, Prototaxites stellaviatori. A tree might release one chemical such as nitrogen, carbon or other essential element, that is needed by another tree through its roots. You might even wonder how young trees are able to grow in the dark canopy of a forest floor. What chance do these seedlings really have hidden under the darkening canopy? They survive due to the fact that the seedlings actually receive extra nutrients from the older overhanging neighbors allowing the seedlings to thrive rather than die off in their twilight realm. Does this indicate the intelligent quality of empathy or just a form of symbiosis? We don’t know yet.
The relationship between plants and the fungal world is not limited to communication either. Some plants serve as homes for endophytic fungi (fungi that grow inside of some plants) that protect the plant from animals that eat them, by producing toxins. The fungi are extremely effective in their work too. Not only do the fungi protect the plant against foraging insects and nematodes but also grazing herbivores.
The fungal endophyte, Neotyphodium coenophialum, found in tall fescue (Festuca arundinacea) costs the cattle industry of the United States millions of dollars every year by causing a form of toxicosis which can lead to aborted fetuses of wildlife and of grazing domestic animals as well (Note that the grass was introduced to North America and is not native to the continent; its original home is Europe, Central Asia and Northern Africa).
Other plants have a relationship with symbiotic bacteria. For example, legume plants have nitrogen-fixing bacteria of the genus Rhizobium, found in nodules of their roots, that fix nitrogen from the air for the plant to use. In exchange, the plants supply sugars to the bacteria through their photosynthesis. That is the reason that many farmers will, at times, alternate growing crops from one species such as a non-legume crop such as wheat or corn to a legume species, such as soybeans, to re-energize the field with nitrogen.
Plants also seem to display a behavior probably best described as intentionality; intentionality is a deliberate behavior and could indicate an awareness of their surroundings. In a growing parasitic vine known as the dodder (Cuscuta sp.), the plant rises up from its ground base to seek out a stem to attach to. It is not random at all, but appears to show an “intentionality” to select which plants to grab onto—those that are most nutrient rich. In one experiment, when offered a range of plant species, the dodder seemed to prefer the fleshy tomato plant. The plant may even “know” which stem of the victimized plant is the most healthy demonstrated by the number of coils that it wraps around. Terry Goodkind wrote about a parasitic alien vine in his Sword of Truth fantasy series. The bizarre vine winds itself around trees eventually killing them. To add further fear to the plants, they will also bite at nearby animals injecting them with venomous toothlike thorns.
Even non-parasitic climbing vines appear to “search” for something to attach to, showing some “intentionality” looking for the best options for growth and stability. So we come to the question as to whether or not plants have “free-will” able to make their own choices or are the responses merely mechanistic in nature as suggested by a number of botanists.
Other plants seem to have this “intentionality” or awareness of their surroundings in their root networks. It has been found that a root will shift its direction, demonstrating an awareness of its surroundings, to avoid an obstacle such as a root of another plant or a rock, before it actually comes into contact with the object.
Plants have still not finished with their behavioral marvels. They also appear to be able to select the genetic material that they pass on to succeeding generations. A recent study found evidence that plants, when they produce seeds, actually are able to erase proteins that carry information about stressful environmental conditions experienced by the parental plants such as extreme drought or cold so that the seeds can move onto new environments and adapt in their own way. In effect, the genetic system of the plant is “deciding” on what is best left forgotten.
So are we seeing a sensitive conscious organism or a lifeform that is a collective complexity of chemical reactions? We must remember that plants cannot escape their situation because they are really immobile, and have to develop where they are. Ever see a weed growing through a crack on hot pavement on a summer day? It would likely not be the first choice for a place to grow and thrive. An animal, on the other hand, would merely move on to another locale but the plant must remain in place and make the best of a bad situation. As a result, plants have developed a complex and sensitive sensory system to let them survive in ever-changing conditions.
Though many researchers see this behavior as mechanical or adaptive behavior, there are others that feel that plants are exhibiting changing responses to the various changing stimuli of their environments, much like animals do when confronted by a new challenge, a sign of intelligence. Still others, however, believe that they are conscious but not necessarily self-conscious. Their consciousness is an awareness of where they are in space and react accordingly to that position. Perhaps we will only find the true answer when we overcome our own animal-based biases when studying plants.
Conscious or not, vegans will want to know whether or not plants feel pain. We can rest assured that they do not feel pain in the same way that animals do since they do not have the nervous systems to transmit the sensation of pain to pain receptors. They do react, though, to stimuli and some may see this as a reaction to pain but others will see it as just another adaptive response to their environment. Examples of plants releasing chemicals and sounds without that processing from a central system could be more of a response to a stimulus no different than when a plant responds to sunlight, soil conditions or water. Animals suffer pain because they are able to process it through their central nervous system, but plants do not have this central system that we are aware of. As a result, the jury is still out as to whether or not plants are feeling pain at all.
In one study, researchers cut tobacco and tomato plants and then recorded the response with a microphone at a distance of ten centimeters. The plants emitted a sound at between twenty and one-hundred kilohertz-the commonly quoted range for average human hearing is between 0.02 to 20 kilohertz-which conveyed their distress to other organisms and plants in the vicinity. The tomato plant, in particular, continued to emit twenty-five sounds over the course of an hour. The tobacco plant sent out fifteen distress calls during this same time. The researchers then changed the “painful” event, this time depriving the plants of water, and found that each plant reacted differently. For the tomato plant the lack of water caused it to emit thirty-five distress calls over an hour and the tobacco plant made only eleven. The reactions changed when the stressor changed’ their sounds were louder when not watered than when being cut. The researchers further looked at the different responses to other conditions such as heavy rain or wind. Research is still ongoing and no conclusion as to the significance has been made. The research may have a practical impact in that it might show farmers one day what exactly is impacting their crops; almost like your plants talking to you.
We find tales of horror fiction in which plants make sounds but not to indicate distress, but rather to trap their human victims, not unlike the tales of the ya-te-veo described by Buel. Scott Smith’s The Ruins is about a group of tourists out to explore some Mayan ruins, some of which are covered in vines that have the ability to mimic certain sounds, such as a cell phone ring or a human voice, drawing the human victims closer to their deadly embrace. Joe Hill and his father, Stephen King, wrote of a vista of tall grass, in their novella, In the Tall Grass, that appears to be able to mimic human sounds, drawing its victims in.
Is there a possible controlling brain in a plant to encapsulate this hypothetical intelligence and even the feeling of pain as it does in animals? The idea goes back to the mid-nineteenth century when Charles Darwin who studied plants extensively in addition to coming up with evolutionary theory through natural selection, saw that the “brain” of plants was in the roots. He felt that the brain was below the surface out of sight whereas the reproductive organs were above the ground for all to see. Some botanists are fence-sitters when it comes to the idea of a plant brain.
If I were to tell you that there was an animal that builds cities, farms and cultivates fungi, raises livestock for its own consumption, wage wars amongst one another, carries out slave raids, teach one another and problem solve such as the building of bridges over water courses, you might think that we are talking about humans or some alien intelligent race; however, we are talking about ants. Ants are the most abundant form of animal life on the planet and they are highly successful through their hivelike behavior. Perhaps, rather than individual plants being intelligent, some botanists suggest that plant intelligence should be likened to that that of insect colonies such as ants, termites and some bees, mindless individuals, organized into a network to carry out seemingly intelligent behavior. Much of the recent research on plant intelligence has been inspired by the science of networks, computing and swarm behavior which has demonstrated more advanced behavior in the absence of actual brains. Perhaps this could explain a possibility of the behavior in plants, seemingly intelligent but without a true brain. The one thing that differentiates social insects such as ants from people in terms of intelligence is that the information is not passed down to its offspring; the behavior is purely instinctive in spite of appearing intelligent; this could also be the same with plants, seemingly intelligent but still strictly a response to the surrounding environment.
There is also the theory that there may be intelligence found at the level of the individual cell arranged in a network. Could this be the case of plants, that their cells are arranged in some sort of network or a network amongst several plants to create a sort of intelligence? Some species of slime mould of the Physarum genus are described by slime mould researcher, Princeton University ecology professor, the late John Tylor Bonner as “nothing more than a bag of amoebae encased in a thin slime sheath, yet manage to have various behaviors that are equal to those of animals that possess muscles and nerves with ganglia-that is, simple brains.” In spite of appearing to be nothing more than a collection of cells, many experiments have been able to demonstrate that the cells are able to learn about their environment and predict unfavourable conditions. They have even been shown to be able to find their way back to one another after having been separated.
In spite of the lack of a known “brain,” some writers have written about intelligent plants. Perhaps the most famous of such tales is John Wyndham’s 1951 classic, The Day of the Triffids. The stage for the story is set by a meteor shower where everyone on Earth who sees it is blinded. The protagonist, having had surgery on his eyes, is spared and finds a whole new world when he removes the bandages from his eyes; people around him are all blind. To complicate things, this blind society must survive an onslaught strange plant form known as triffids that appeared all over the world years before; triffids are plants able to grow to a height of around two meters, walk upon their roots and kill humans with a lash of one of their poisonous stingers. There is a sequel to the novel by Simon Clark entitled The Night of the Triffids.
Creepers by Bryan Dunn is about a plant that has been genetically engineered to be drought-tolerant. The genetic change though seems to have created not only the drought-resistance but a plant with a mind of its own. American writer, Algernon Blackwood is well-known for his creepy tales including The Willows. The story follows a couple of friends on a canoe trip down the Danube with Nature being personified as a menacing character; the overhanging willows especially appear as masses that “moved with a will of their own.” Blackwood was a master of creating a eerie setting in all of his stories. Lord of the Rings by J. R. R. Tolkien contains a number of descriptions of plants in his fictional Middle Earth; the Ents, in particular, are mobile intelligent trees who act as “shepherds of the forest.”
There are also stories about intelligent alien plants. Edgar Rice Burroughs, author of the Tarzan series, also wrote a number of novels, his John Carter series, that took place on a fictional Mars known as Barsoom; Burrough’s Mars is populated by a number of intelligent races, one of which is an intelligent plant race. Grandiose science fiction writer Olaf Stapleton’s Star Maker also speaks to not only an intelligent plant species, but the rise and fall of an entire plant civilization. Unlike Burrough’s intelligent plants of Mars, which are easily exchanged with animals, Stapleton takes the time to describe why the species rose and fell in the first place, a true staple of good science fiction. The plant intelligence of Stapleton arose on a small hot world that received a greater amount of solar energy than the plants of our Earth; the plants remained stationary during the day bathed in the sunlight and communing with their spiritual nature, and by night they had evolved mobility. The species’ demise came about with the temptation to avert their daytime plantlike stage, instead utilizing injections of energy rather than the light of their star. They had in a sense lost their “plantness,” and hence their spiritual side, attained through their communion with their sun. The success of their technology allowed them to breed to a point where the planet could no longer sustain them, either artificially or naturally.
A more recent intelligent alien plant story is Semiosis, by Sue Burke, which is a part of a first-contact trilogy. The trilogy follows the forced landing of a spacecraft on an alien world, Pax. The title refers to a communication form utilizing signs. In the case of the planet, the communication is between the landed humans and the indigenous sentient plants. Ursula Le Guin wrote Vaster than Empire and More Slow about a planet which is outside of the area of the galaxy that had already been colonized. A team arrives on a planet which appears to be filled with vegetation but mysteriously devoid of any animal species and hence the potential for intelligent life. As the story moves along, we find that the entire planet is covered by an intelligence extending over all of the vegetation of the planet.
John Jakes, famous more for his historical fiction, also wrote science fiction early in his career. His The Dreaming Trees describes the colonization of the galaxy; however, it turns out that there is a dearth of Earth-like worlds for humans to settle. One likely world for colonization has an alien lifeform that are known as dreaming trees. They are described as reaching 150 meters in height, with long branches that stretch down to the ground. One feature that makes the trees very valuable to humans is the fact that they change colours on a constant basis. Other than their value, the trees are looked at as just a plant lifeform that can be largely ignored. In one scene however, that all changes. As the antagonist picks up a weapon from the ground, it is grabbed out of her hand by one of the trees. The battle has just begun.
China Mieville wrote the Bas-Lag series of fantasy tales where both magic and technology live side-by-side; the tales contain a sentient race of cactus people.
It is tempting to put a anthropomorphic spin on the five basic senses to describe some of the behaviors of plants, but it does not really work. Plants “see” light and direct their growth towards that light which is essential to their survival, but they don’t really see. The same would go for the other senses such as hearing, taste, touch and smelling. They may even have senses that we are not aware of with our “animal bias.” Whereas animals avoid situations of threat, plants do not have that luxury and really harm is not really an issue in many cases, since plants do regenerate on their own. Even a chainsaw cutting down a tree and leaving a stump; that stump will grow new shoots when conditions are right, in a lot of cases provided with nutrients from other plants, required through the mycelial network beneath the ground. There may come a day when science sees plants as being sentient and feel pain. One day we may have a whole new way of looking at those seeking the light.
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