Table of Contents (click to expand)
- Plants In Nature
- Stress Response In Plants
- A Final Word
Plants do feel stress from the environment and other activities, but their response to such stimuli is very different from our idea of stress, since plants lack a nervous system and traditional brain.
Imagine that you are walking home after a long day at work, during which your boss yelled at you multiple times, you started showing the early signs of a cold, and you missed a deadline for an important client. As you step off the curb to cross the street, the screeching horn of an oncoming car shocks you into action and you leap back in time to avoid being struck. Your heart is racing, your breathing gets shallow and you immediately break out into a sweat. Suffice to say, you are stressed out in every possible way—physically, emotionally and psychologically.
However, while human beings and animals experience and demonstrate stress in ways that we largely understand, many people wonder if the same thing is true of plants. Basically, what is the equivalent of a plant feeling nervous before a test? Or a plant feeling a surge of energy after finding itself in a dangerous situation? Can plants feel stress and pain, or is that something only sentient life can experience?
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Plants In Nature
When a human being or other mobile sentient creature encounters a stressful experience, such as narrowly avoiding an accident or attempting to elude a predator, they are often benefitted by their “flight or fight” reactions. They must choose to either fight and defend themselves, or run away and seek shelter from the threat. Plants, however, are quite literally rooted to the ground, and are therefore unable to escape from or remove themselves from dangerous or uncomfortable situations.
When we think about predator and prey in the wild, we rarely think of plants as fitting into the same paradigm, but they do! Remember that every herbivore and omnivore on the planet (organisms that eat plants) are predators from the perspective of plants! Furthermore, aside from sentient predators, plants must also be able to defend against natural threats, such as rainfall, excess heat, disease, freezing temperatures and drought. Plants that are unable to withstand or avoid such stressors will be unable to grow, produce viable seeds and reproduce. Clearly, given the nearly 400,000 species of plants that have been identified around the globe thus far, the flora of Earth has developed its own ways to respond to stress.
Stress Response In Plants
When a plant undergoes a difficult period, stressed by weather, predators or disease, there are not many options—adapt or perish. The less preferred option is death, but it’s not always a terrible option. Many plants are short-lived because they lack any adaptations to survive challenging times, but their reproduction is often taken care of by then, so succumbing to death isn’t a failure in the grand scheme of their species.
In terms of plants that are able to survive and “weather the storm”, per se, they acclimate by developing ways to continue producing seeds, despite the challenges to their homeostasis. Plants that can deal with fluctuations in temperature and water levels without dying are often referred to as hardy plants, versus those that are susceptible to small fluctuations in their surroundings. Hardy plants gradually evolved certain characteristics as their entire population acclimated to new conditions. Some of these characteristics allow them to overcome environmental challenges, such as heat-shock proteins, or the ability to change their leaf size depending on growing conditions. These adaptations are the result of natural selection, and provide long-term protection and resilience against regular or seasonal stress.
Equivalent Of A Flight-or-fight Response
Finally, there is the acute stress response of plants, which is most similar to our own fight-or-flight response. In the event of an immediate threat, such as a predator eating its leaves or a fungi beginning to grow on its roots, a plant will have a hormonal response. In the case of humans, our hormone regulation is controlled by the endocrine system, while neurotransmitters are managed by the nervous system. The brain directs these systems to release critical compounds at precisely the right time to maintain health and homeostasis. Plants, however, do not have a nervous system, endocrine system or brain; instead, every single plant cell is able to produce its own hormones!
Also Read: Can Plants Hear, Smell, See, Touch Or Taste Stuff?
Plant hormones control every single step in the growth, development, reproduction, and defense of the plant, which includes stress response. The simple chemicals used by plants are transported where they’re needed through four methods—cytoplasmic streaming, slow diffusion, via xylem, or via phloem. Most of the hormones are only used during certain stages of a plant’s life cycle, while others, such as stress response hormones, can be produced and implemented at any time.
Abscisic Acid
Abscisic acid is a particularly popular plant growth regulator that is generated by the chloroplasts when a plant is experiencing stress. It will inhibit bud growth and may impact bud dormancy, when the conditions aren’t right for growth. In the case of water stress, or drought, this same hormone can close the stomata, preventing water loss through evaporation.
Salicyclic Acid
Salicylic acid is a hormone that functions as an alarm system within plants. If a plant is being attacked by some sort of pathogen, it will be released from the cells to aid in the defense. Furthermore, it can be aromatically released as a warning to neighboring plants of the pathogen attack, so that they can better prepare themselves. This type of “communication” between plants is often mistaken for intelligence or cognition, but is instead the result of chemical pathways automatic triggers.
Jasmonic Acid
Jasmonates, particularly jasmonic acid, is a class of hormones that has a number of functions. It works as both a defensive substance and an airborne pathogen warning system to other leaves of the plant and nearby plants. In terms of its defensive characteristics, the powerful aromatics are unpleasant to predators, both above- and below-ground herbivores. Nitric oxide is yet another simple compound that is deeply involved in the signaling of stress response in plants.
Jasmonic acid (Photo Credit : PNOIARSA/Shutterstock)
In conjunction with dozens of other plant hormones that are produced, used and catabolized throughout every stage of a plant’s life cycle, these defensive hormones play a key role in protecting individual plants from a variety of threats.
Also Read: How Do Plants Defend Themselves?
A Final Word
Just because plants don’t have a nervous system like humans doesn’t mean they aren’t able to recognize and respond to danger. While the debate over whether plants can “feel pain” often veers into philosophy, the question of whether plants feel stress is not in question. Stress is a part of life, as environmental conditions change and organisms are forced to adapt or respond.
Stress in plants is not necessarily a bad thing, but we often associated and anthropomorphize it as a “painful” experience. In some cases, stress allows a plant to learn more about its environment so it can be better prepared for the future. In other cases, stress drives the process of natural selection and greater adaptations so a species will be able to persist. This isn’t all that different from the human experience with difficult situations; for some people, there is no better motivator to overcome a challenge than a solid dose of stress!
References (click to expand)
- Okada, K., Abe, H., & Arimura, G.-. ichiro . (2014, November 4). Jasmonates Induce Both Defense Responses and Communication in Monocotyledonous and Dicotyledonous Plants. Plant and Cell Physiology. Oxford University Press (OUP).
- Wasternack, C. (2007, May 18). Jasmonates: An Update on Biosynthesis, Signal Transduction and Action in Plant Stress Response, Growth and Development. Annals of Botany. Oxford University Press (OUP).
- Loake, G., & Grant, M. (2007, October). Salicylic acid in plant defence—the players and protagonists. Current Opinion in Plant Biology. Elsevier BV.
- Arasimowicz, M., & Floryszak-Wieczorek, J. (2007, May). Nitric oxide as a bioactive signalling molecule in plant stress responses. Plant Science. Elsevier BV.
- HIRON, R. W. P., & WRIGHT, S. T. C. (1973). The Role of Endogenous Abscisic Acid in the Response of Plants to Stress. Journal of Experimental Botany. Oxford University Press (OUP).
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FAQs
Do plants feel stress? ›
Plants can sense a lot about their environment and it can cause them stress. Unlike most humans and animals though, when plants face predation, damage, or environmental changes they can't run away and hide. Sessile – or stalkless – plants evolved to be incredibly sensitive to their environment in order to survive.
Can plants feel suffering? ›The simple answer is that, currently, no one is sure whether plants can feel pain. We do know that they can feel sensations. Studies show that plants can feel a touch as light as a caterpillar's footsteps. But pain, specifically, is a defense mechanism.
Do plants feel pain or not? ›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. Uprooting a carrot or trimming a hedge is not a form of botanical torture, and you can bite into that apple without worry.
How do we know plants don't feel pain? ›Unlike us and other animals, plants do not have nociceptors, the specific types of receptors that are programmed to respond to pain. They also, of course, don't have brains, so they lack the machinery necessary to turn those stimuli into an actual experience. This is why plants are incapable of feeling pain.
Do plants feel emotions? ›Do Plants Have Feelings (Or Emotions)? No – unlike humans and non-human animals, plants do not have feelings. It is undeniable that a plant can respond to environmental stimuli, like turning towards the light or closing over a fly.
Can plants feel depressed? ›And since plants do not have brains, nor a central nervous system (which is how intelligence is defined), it is said to be impossible for them to have emotions and the ability to reason or feel.
Do plants feel love? ›And since plants do not have brains, nor a central nervous system (which is how intelligence is defined), it is said to be impossible for them to have emotions and the ability to reason or feel.
Do plants have thoughts? ›Plants don't have a central nervous system, so thought (as we normally define it) isn't possible. But plants can sense their environment, respond to insect attacks and are even capable of limited movement.
Do plants feel anger? ›Nor does it experience fear, anger, relief or sadness as it topples to the ground. Trees — and all plants, for that matter — feel nothing at all, because consciousness, emotions and cognition are hallmarks of animals alone, scientists recently reported in an opinion article.
Do plants cry when you cut them? ›What Is a Plant's Scream? According to a study on tobacco and tomato plants by Tel-Aviv University, researchers found that when stressed, certain plants produce an ultrasonic sound that is undetectable to the human ear. Keep in mind that being stressed can be caused by drought, insects, and yes, by being cut.
Do plants like being touched? ›
Your plants really dislike when you touch them, apparently. A new study out of the La Trobe Institute for Agriculture and Food has found that most plants are extremely sensitive to touch, and even a light touch can significantly stunt their growth, reports Phys.org.
Do plants feel human touch? ›Scientists already know that plants are highly sensitive to touch of any kind, and even have a word for this phenomenon, “thigmomorphogenesis.” If you've ever touched a Mimosa pudica (also known as the “sensitive plant”) you have already witnessed this phenomenon first hand—the Mimosa's fan-like leaves close up like, ...
Can plants hear you? ›Plants are surprising organisms—without brains and central nervous systems, they are still able to sense the environment that surrounds them. Plants can perceive light, scent, touch, wind, even gravity, and are able to respond to sounds, too.
Do plants enjoy music? ›For most plants playing classical or jazz music caused growth to increase, while harsher metal music induced stress. This may be because the vibrations of metal music are too intense for plants and stimulate cells a little too much. We think of this like massaging your plant with a song – they prefer a gentler touch.
Can trees hear us? ›But can they hear? They have no specialized structure to perceive sound like we do, but a new study has found that plants can discern the sound of predators through tiny vibrations of their leaves — and beef up their defenses in response.
Do plants respond to kindness? ›While flowers and other members of the plant kingdom seem not to complain when we pinch their buds or step on them, they are fully aware of what's happening and rapidly respond to the way they're treated, scientists have discovered.
Do trees have thoughts? ›Mountains of research have confirmed that plants have intelligence and even beyond that consciousness by many of the same measures as we do. Not only do they feel pain, but plants also perceive and interact with their environment in sophisticated ways.
Do plants get traumatized? ›Transplant Shock occurs when a plant is uprooted or placed in a new pot and shows distressed symptoms afterwards. Plant Shock is a more generalized term that happens when there is stress due to abrupt changes in environment like temperature changes, water stress, over fertilizing, or drastic changes in light.
Do plants respond to talking? ›While the studies suggest that sound may spur plants to faster growth, there is no definitive evidence that a gift of gab will turn you into a green thumb. Ideal conditions for growth have more to do with temperature than talk.
Do plants recognize their owners? ›"While plants don't appear to complain when we pinch a flower, step on them or just brush by them while going for a walk, they are fully aware of this contact and are rapidly responding to our treatment of them," he added.
Do plants have a soul? ›
The reason for this is that, despite the lack of any kind of cognition, plants have souls too, according to Aristotle's widely-accepted theory: trees and flowers nourish themselves, they grow, and propagate, and so they have what was usually called a vegetative soul.
Do plants remember us? ›Things happen to plants, and as far as I know, they go on as before. They don't have brains. They have no way to “remember” anything. They're not animals.
Do plants have memories? ›Like humans, plants have memories too, although they do it differently. For example, many plants sense and remember prolonged cold during winter to ensure that they flower in spring.
Do plants see you? ›Plants detect visible and invisible electromagnetic waves. Unlike plants, we can only detect visible electromagnetic waves. Although plants can see a much larger spectrum than we do, they don't see it in images.
Do plants have voices? ›Plants emit audio acoustic emissions between 10–240 Hz as well as ultrasonic acoustic emissions (UAE) within 20–300 kHz. Evidence for plant mechanosensory abilities are shown when roots are subjected to unidirectional 220 Hz sound and subsequently grow in the direction of the vibration source.
Do plants feel as much pain as animals? ›As explained by plant biologist Dr. Elizabeth Van Volkenburgh, all living organisms perceive and respond to painful touch, but plants do not perceive or “feel” pain the same way that animals do because they lack a nervous system and brain.
Can plants get lonely? ›Plants will definitely experience something like being “lonely” in pots because they miss out on underground connections. The majority of plants form symbioses with fungi underground, via their roots. Physical connections between the roots of different plants are …
Why shouldn't you touch plants at night? ›In addition, at night you may not be able to see dangerous, spiders, bugs, or snakes that make their home in trees. In addition, at night it is difficult to identify dangerous plants (e.g. poison ivy, poison oak, stinging nettle, etc.).
Do plants like being alone? ›'The fact that houseplants thrive by our presence shows that they also have needs which go beyond just needing food, water and a nice ambient temperature,' explains horticultural expert Angela Slater. 'It's safe to say that plants will not fare as well in the silence when their owner isn't home. '
Can trees talk to each other? ›Trees share water and nutrients through the networks, and also use them to communicate. They send distress signals about drought and disease, for example, or insect attacks, and other trees alter their behavior when they receive these messages.” Scientists call these mycorrhizal networks.
What plants don't like to be touched? ›
The mimosa pudica — also known as the sleepy plant or touch-me-not — reacts dramatically when touched or shaken.
Can trees feel you hug them? ›There is also fairly robust evidence that plant cells can perceive and respond to pressure waves, like the kind that are generated by sound in the environment and touch — like, say someone walking up to a tree and hugging it.
Do plants like human voices? ›Do Plants React to Human Voices? Here's the good news: plants do respond to the sound of your voice. In a study conducted by the Royal Horticultural Society, research demonstrated that plants did respond to human voices.
Do plants like being around other plants? ›Plants "Listen" to the Good Vibes of Other Plants. A new study found that plants grown next to certain other plants are healthier than those grown in isolation.
Do plants like coffee? ›Is Coffee Good for Plants? Yes, and yes! Coffee beans are rich in minerals such as magnesium, calcium, phosphorus, nitrogen, and potassium. Phosphorus and potassium improve yields, and nitrogen is involved in photosynthesis, which helps plants grow faster.
Why talk to your plants? ›Many found that at the average human conversational tone (70 decibels) there was increased production in plants. Not only will your plants benefit from your conversations but you may get a psychological boost as well. Spending time with and around plants is calming and promotes good mental and physical health.
Can plants hear water? ›Studies have described plants communicating with each other, using light and scent to see and hear, even appearing to remember weather patterns or being eaten. The latest addition to this blooming area of literature: plants can detect the sound of water and use it to guide the growth of their roots.
Do trees remember you? ›They can count, learn and remember; nurse sick neighbors; warn each other of danger by sending electrical signals across a fungal network known as the “Wood Wide Web”; and, for reasons unknown, keep the ancient stumps of long-felled companions alive for centuries by feeding them a sugar solution through their roots.
Do plants talk to each other? ›In this case, Darwin's root-brain hypothesis was wrong, but more modern research shows that plants can communicate. They speak with other plants as well as with animals and even people. They do this primarily using chemicals and sound.
Do trees have memory? ›During their lifetime, trees are not only able to adapt quickly to new conditions but can even pass on the 'memory' of such environmental changes to the next generation. This amazing ability has been proved for the first time by researchers at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL).
Can plants feel fear? ›
Nor does it experience fear, anger, relief or sadness as it topples to the ground. Trees — and all plants, for that matter — feel nothing at all, because consciousness, emotions and cognition are hallmarks of animals alone, scientists recently reported in an opinion article.
Can plants feel lonely? ›Plants will definitely experience something like being “lonely” in pots because they miss out on underground connections. The majority of plants form symbioses with fungi underground, via their roots. Physical connections between the roots of different plants are …
Do plants have souls? ›The reason for this is that, despite the lack of any kind of cognition, plants have souls too, according to Aristotle's widely-accepted theory: trees and flowers nourish themselves, they grow, and propagate, and so they have what was usually called a vegetative soul.
Can plants miss you? ›They will miss you breathing out. Carbon dioxide increases photosynthesis, therefore spurring plant growth. With less humans around during the day, the Co2 levels will have decreased.
Do plants feel scream? ›Even drying soil can produce faint sounds, reports Nicolette Lanese for Live Science. All this stress-induced “screaming” wasn't in a range detectable by human ears. But organisms that can hear ultrasonic frequencies—like mice, bats or perhaps other plants—could hear the plants' cries from as far as 15 feet away.
Can plants hear you talk? ›Do Plants React to Human Voices? Here's the good news: plants do respond to the sound of your voice. In a study conducted by the Royal Horticultural Society, research demonstrated that plants did respond to human voices.
Do plants know I love them? ›They conducted all sorts of experiments with plants – playing music, talking to plants, vibrations, etc. But their findings were discredited. Now fast forward nearly 50 years, and it has never been scientifically proven that plants have feelings.