Plant intelligence
Encyclopedia
In botany
, plant intelligence is the ability of plant
s to sense the environment and adjust their morphology
, physiology
and phenotype
accordingly. Research draws on the fields of plant physiology
, ecology
and molecular biology
.
Intelligence
is an umbrella term
describing abilities such as the capacities for abstract thought
, understanding
, communication
, reason
ing, learning
, learning from past experiences, plan
ning, and problem solving
. Studies indicate plants are capable of problem solving
and communication
.
. Plants do not have a brain or neuronal network, but reactions within signalling pathways may provide a biochemical basis for learning and memory. Controversially, the brain is used as a metaphor in plant intelligence to provide an integrated view of signalling, (see plant neurobiology
).
Plant cells can be electrically excitable and can display rapid electrical responses (action potential
s) to environmental stimuli. These action potentials can influence processes such as actin
-based cytoplasmic streaming, plant organ movements
, wound responses, respiration, photosynthesis
and flowering.
. For example, they can produce different toxins (phytoalexin
s) against invaders or they can induce rapid cell death in invading cells to hinder the pests from spreading out. These strategies depend on quick and reliable recognition-systems.
detect the chemical and prepare for the attack by producing chemicals that defend against insects or attract predators.
s, cryptochrome
s and phytochrome
s) each reacting very specifically to certain wavelengths of light. These light-sensors tell the plant if it's day or night, how long the day is (photoperiodism
), how much light is available and from where the light comes. Plants also can detect harmful ultraviolet B-rays and then start producing pigments which filter out these rays.
) makes its thin leaves point down at the slightest touch and carnivorous plant
s such as the Venus flytrap
snap shut by the touch of insects.
Mechanical perturbation can also be detected by plants. Jasmonate
levels also increase rapidly in response to mechanical perturbations such as tendril coiling.
Poplar
stems can detect reorientation and inclination (equilibrioception
).
However, plant intelligence fits with the definition of intelligence proposed by David Stenhouse
in a book he wrote about evolution where he described it as "adaptively variable behaviour during the lifetime of the individual".
It is also argued that a plant cannot have goals because operational control of the plant's organs is devolved.
studied the movement of plants and in 1880 published a book The Power of Movement in Plants
. In the book he concludes:
India
n scientist Sir Jagdish Chandra Bose
began to conduct experiments on plants in the year 1900. He found that every plant and every part of a plant appeared to have a sensitive nervous system
and responded to shock by a spasm just as an animal muscle does.
Bose's experiments stopped at this conclusion, but American polygraph
expert Cleve Backster
conducted research that led him to believe that plants can communicate with other lifeforms. Backster's interest in the subject began in February 1966, when Backster wondered if he could measure the rate at which water rises from a philodendron's root area into its leaves. Because a polygraph or "lie detector" can measure electrical resistance, and water would alter the resistance of the leaf, he decided that this was the correct instrument to use. After attaching a polygraph to one of the plant's leaves, Backster claimed that, to his immense surprise, "the tracing began to show a pattern typical of the response you get when you subject a human to emotional stimulation of short duration".
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
, plant intelligence is the ability of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s to sense the environment and adjust their morphology
Plant morphology
Plant morphology or phytomorphology is the study of the physical form and external structure of plants. This is usually considered distinct from plant anatomy, which is the study of the internal structure of plants, especially at the microscopic level...
, physiology
Plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...
and phenotype
Phenotypic plasticity
Phenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. Such plasticity in some cases expresses as several highly morphologically distinct results; in other cases, a continuous norm of reaction describes the functional interrelationship...
accordingly. Research draws on the fields of plant physiology
Plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...
, ecology
Plant ecology
Plant ecology is a subdiscipline of ecology which studies the distribution and abundance of plants, the interactions among and between members of plant species, and their interactions with their environment...
and molecular biology
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
.
Intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
is an umbrella term
Umbrella term
An umbrella term is a word that provides a superset or grouping of concepts that all fall under a single common category. Umbrella term is also called a hypernym. For example, cryptology is an umbrella term that encompasses cryptography and cryptanalysis, among other fields...
describing abilities such as the capacities for abstract thought
Abstraction
Abstraction is a process by which higher concepts are derived from the usage and classification of literal concepts, first principles, or other methods....
, understanding
Understanding
Understanding is a psychological process related to an abstract or physical object, such as a person, situation, or message whereby one is able to think about it and use concepts to deal adequately with that object....
, communication
Communication
Communication is the activity of conveying meaningful information. Communication requires a sender, a message, and an intended recipient, although the receiver need not be present or aware of the sender's intent to communicate at the time of communication; thus communication can occur across vast...
, reason
Reason
Reason is a term that refers to the capacity human beings have to make sense of things, to establish and verify facts, and to change or justify practices, institutions, and beliefs. It is closely associated with such characteristically human activities as philosophy, science, language, ...
ing, learning
Learning
Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...
, learning from past experiences, plan
Plan
A plan is typically any diagram or list of steps with timing and resources, used to achieve an objective. See also strategy. It is commonly understood as a temporal set of intended actions, through which one expects to achieve a goal...
ning, and problem solving
Problem solving
Problem solving is a mental process and is part of the larger problem process that includes problem finding and problem shaping. Consideredthe most complex of all intellectual functions, problem solving has been defined as higher-order cognitive process that requires the modulation and control of...
. Studies indicate plants are capable of problem solving
Problem solving
Problem solving is a mental process and is part of the larger problem process that includes problem finding and problem shaping. Consideredthe most complex of all intellectual functions, problem solving has been defined as higher-order cognitive process that requires the modulation and control of...
and communication
Communication
Communication is the activity of conveying meaningful information. Communication requires a sender, a message, and an intended recipient, although the receiver need not be present or aware of the sender's intent to communicate at the time of communication; thus communication can occur across vast...
.
Problem solving
Plants adapt their behaviour in a variety of ways:- Active foraging for light and nutrients. They do this by changing their architecture, physiology and phenotype.
- Leaves and branches are positioned and oriented in response to light source.
- Ability to detect soil volume and adapt growth accordingly independently of nutrientPlant nutrition'Plant Nutrition is the study of the chemical elements that are necessary for growth. In 1972, E. Epstein defined 2 criteria for an element to be essential for plant growth:# in its absence the plant is unable to complete a normal life cycle or...
availability. - Adaptively defend against herbivoresInducible plant defenses against herbivoryPlants and herbivores have co-evolved together for 350 million years. Plants have evolved many defence mechanisms against insect herbivory. Such defences can be broadly classified into two categories: permanent, constitutive defences, and temporary, inducible defences...
.
Mechanisms
In plants, the mechanism responsible for adaptation is signal transductionSignal transduction
Signal transduction occurs when an extracellular signaling molecule activates a cell surface receptor. In turn, this receptor alters intracellular molecules creating a response...
. Plants do not have a brain or neuronal network, but reactions within signalling pathways may provide a biochemical basis for learning and memory. Controversially, the brain is used as a metaphor in plant intelligence to provide an integrated view of signalling, (see plant neurobiology
Plant neurobiology
Plant neurobiology studies those aspects of plant physiology with perceived similarities to the neurobiological processes of animals. It concerns mostly the sensory adaptive behaviour of plants and plant electrophysiology. J. C. Bose the Indian scientist is credited as the first person to research...
).
Plant cells can be electrically excitable and can display rapid electrical responses (action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...
s) to environmental stimuli. These action potentials can influence processes such as actin
Actin
Actin is a globular, roughly 42-kDa moonlighting protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
-based cytoplasmic streaming, plant organ movements
Rapid plant movement
Rapid plant movement encompasses movement in plant structures occurring over a very short period of time, usually under one second. For example, the Venus Flytrap closes its trap in about 100 milliseconds. The Dogwood Bunchberry's flower opens its petals and fires pollen in less than 0.5 milliseconds...
, wound responses, respiration, photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
and flowering.
Plant perception
Plants have many strategies to fight off pestsInducible plant defenses against herbivory
Plants and herbivores have co-evolved together for 350 million years. Plants have evolved many defence mechanisms against insect herbivory. Such defences can be broadly classified into two categories: permanent, constitutive defences, and temporary, inducible defences...
. For example, they can produce different toxins (phytoalexin
Phytoalexin
Phytoalexins are antimicrobial substances synthesized de novo by plants that accumulate rapidly at areas of incompatible pathogen infection. They are broad spectrum inhibitors and are chemically diverse with different types characteristic of particular plant species...
s) against invaders or they can induce rapid cell death in invading cells to hinder the pests from spreading out. These strategies depend on quick and reliable recognition-systems.
Alarm signals
Wounded tomatoes are known to produce the volatile odour methyl-jasmonate as an alarm-signal. Plants in the neighbourhood can thendetect the chemical and prepare for the attack by producing chemicals that defend against insects or attract predators.
Light
Many plant-organs contain photo-sensitive compounds (phototropinPhototropin
Phototropins are photoreceptor proteins that mediate phototropism responses in higher plants. Along with cryptochromes and phytochromes they allow plants to respond and alter their growth in response to the light environment...
s, cryptochrome
Cryptochrome
Cryptochromes are a class of blue light-sensitive flavoproteins found in plants and animals. Cryptochromes are involved in the circadian rhythms of plants and animals, and in the sensing of magnetic fields in a number of species...
s and phytochrome
Phytochrome
Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum. Many flowering plants use it to regulate the time of flowering based on the length of day and night and to set circadian rhythms...
s) each reacting very specifically to certain wavelengths of light. These light-sensors tell the plant if it's day or night, how long the day is (photoperiodism
Photoperiodism
Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs in plants and animals.Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of the light and dark periods...
), how much light is available and from where the light comes. Plants also can detect harmful ultraviolet B-rays and then start producing pigments which filter out these rays.
Contact Stimuli
The mimosa plant (Mimosa pudicaMimosa pudica
Mimosa pudica , is a creeping annual or perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched or shaken, re-opening minutes later...
) makes its thin leaves point down at the slightest touch and carnivorous plant
Carnivorous plant
Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic...
s such as the Venus flytrap
Venus Flytrap
The Venus Flytrap , Dionaea muscipula, is a carnivorous plant that catches and digests animal prey—mostly insects and arachnids. Its trapping structure is formed by the terminal portion of each of the plant's leaves and is triggered by tiny hairs on their inner surfaces...
snap shut by the touch of insects.
Mechanical perturbation can also be detected by plants. Jasmonate
Jasmonate
Jasmonate and its derivatives are lipid-based hormone signals that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herbivory and plant responses to poor environmental...
levels also increase rapidly in response to mechanical perturbations such as tendril coiling.
Poplar
Poplar
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar , aspen, and cottonwood....
stems can detect reorientation and inclination (equilibrioception
Equilibrioception
Equilibrioception or sense of balance is one of the physiological senses. It helps prevent humans and animals from falling over when walking or standing still. Balance is the result of a number of body systems working together: the eyes , ears and the body's sense of where it is in space ideally...
).
Plant adaptation vs plant intelligence
It has been argued that although plants are capable of adaptation, it should not be called intelligence. "A bacterium can monitor its environment and instigate developmental processes appropriate to the prevailing circumstances, but is that intelligence? Such simple adaptation behaviour might be bacterial intelligence but is clearly not animal intelligence."However, plant intelligence fits with the definition of intelligence proposed by David Stenhouse
David Stenhouse
David Stenhouse was born in Sutton, Surrey, England on 23 May 1932. He proposed the "4-factor" theory of evolutionary intelligence and was active in ethology, education, evolutionary biology and philosophy of science in Australia and New Zealand....
in a book he wrote about evolution where he described it as "adaptively variable behaviour during the lifetime of the individual".
It is also argued that a plant cannot have goals because operational control of the plant's organs is devolved.
History
Charles DarwinCharles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
studied the movement of plants and in 1880 published a book The Power of Movement in Plants
The Power of Movement in Plants
The Power of Movement in Plants is a book by Charles Darwin on phototropism and other types of movement in plants. This book continues his work in producing evidence for his theory of natural selection...
. In the book he concludes:
It is hardly an exaggeration to say that the tip of the radicleRadicleIn botany, the radicle is the first part of a seedling to emerge from the seed during the process of germination. The radicle is the embryonic root of the plant, and grows downward in the soil...
thus endowed [..] acts like the brain of one of the lower animals; the brain being situated within the anterior end of the body, receiving impressions from the sense-organs, and directing the several movements.
India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n scientist Sir Jagdish Chandra Bose
Jagdish Chandra Bose
Acharya Sir Jagadish Chandra Bose, CSI, CIE, FRS was a Bengali polymath: a physicist, biologist, botanist, archaeologist, as well as an early writer of science fiction...
began to conduct experiments on plants in the year 1900. He found that every plant and every part of a plant appeared to have a sensitive nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
and responded to shock by a spasm just as an animal muscle does.
Bose's experiments stopped at this conclusion, but American polygraph
Polygraph
A polygraph measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions...
expert Cleve Backster
Cleve Backster
Cleve Backster is a best known for his experiments with biocommunication in plant and animal cells using a polygraph machine in the 1960s which led to his theory of "primary perception." Backster began his career as an Interrogation Specialist with the CIA, and went on to become Chairman of the...
conducted research that led him to believe that plants can communicate with other lifeforms. Backster's interest in the subject began in February 1966, when Backster wondered if he could measure the rate at which water rises from a philodendron's root area into its leaves. Because a polygraph or "lie detector" can measure electrical resistance, and water would alter the resistance of the leaf, he decided that this was the correct instrument to use. After attaching a polygraph to one of the plant's leaves, Backster claimed that, to his immense surprise, "the tracing began to show a pattern typical of the response you get when you subject a human to emotional stimulation of short duration".