Mimosa pudica | |
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Flower head and leaves | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Fabales |
Family: | Fabaceae |
Subfamily: | Caesalpinioideae |
Clade: | Mimosoid clade |
Genus: | Mimosa |
Species: | M. pudica |
Binomial name | |
Mimosa pudica | |
Mimosa pudica (also called sensitive plant, sleepy plant,[ citation needed ]action plant, humble plant, touch-me-not, touch-and-die, or shameplant) [3] [2] is a creeping annual or perennial flowering plant of the pea/legume family Fabaceae. It is often grown for its curiosity value: the sensitive compound leaves quickly fold inward and droop when touched or shaken and re-open a few minutes later. For this reason, this species is commonly cited as an example of rapid plant movement. Like a number of other plant species, it undergoes changes in leaf orientation termed "sleep" or nyctinastic movement. The foliage closes during darkness and reopens in light. [4] This was first studied by French scientist Jean-Jacques d'Ortous. [5] In the UK it has gained the Royal Horticultural Society's Award of Garden Merit. [3] [6]
The species is native to the Caribbean and South and Central America, but is now a pantropical weed, and can now be found in the Southern United States, South Asia, East Asia, Micronesia, Australia, South Africa, and West Africa as well. It is not shade-tolerant and is primarily found on soils with low nutrient concentrations. [7]
Mimosa pudica was first formally described by Carl Linnaeus in Species Plantarum in 1753. [8] The species epithet, pudica , is Latin for 'shame', 'bashful', or 'shrinking', alluding to its shrinking reaction to contact.
The species is known by numerous common names including sensitive plant, action plant, humble plant, shameplant, and touch-me-not. [3] [2]
The stem is erect in young plants but becomes creeping or trailing with age. It can hang very low and become floppy. The stem is slender, branching, and sparsely to densely prickly, growing to a length of 1.5 m (5 ft). The erect height of M. pudica usually reaches around ~30 cm (~1 ft).
The leaves are bipinnately compound, with one or two pinnae pairs, and 10–26 leaflets per pinna. The petioles are also prickly. Pedunculate (stalked) pale pink or purple flower heads arise from the leaf axils in mid-summer with more and more flowers as the plant gets older. A single flower survives for less than a day, and usually dies completely by the next day. Flowers of M. pudica are very brittle and soft. The globose to ovoid heads are 8–10 mm (0.3–0.4 in) in diameter (excluding the stamens). On close examination, it is seen that the floret petals are red in their upper part and the filaments are pink to lavender. Pollens are circular with approximately 8 microns in diameter.
The fruit consists of clusters of two to eight pods from 1–2 cm (0.4–0.8 in) long each, these being prickly on the margins. The pods break into two to five segments and contain pale brown seeds about 2.5 mm (0.1 in) long. The flowers are insect-pollinated and wind-pollinated. [9] The seeds have hard seed coats which restrict germination and make osmotic pressure and soil acidity less significant hindrances. High temperatures are the main stimuli that cause the seeds to end dormancy. [10]
The roots of Mimosa pudica create carbon disulfide, which prevents certain pathogenic and mycorrhizal fungi from growing within the plant's rhizosphere. [11] This allows the formation of nodules on the roots of the plant that contain endosymbiotic diazotrophs, which fix atmospheric nitrogen and convert it into a form that is usable by the plant. [12]
Mimosa pudica is a tetraploid (2n = 52). [13]
The leaflets also close when stimulated in other ways, such as, warming, touching, blowing, and shaking, which are all encapsulated within mechanical or electrical stimulation. These types of movements have been termed seismonastic movements. This reflex may have evolved as a defense mechanism to disincentivize predators, or alternatively to shade the plant in order to reduce water loss due to evaporation. The main structure mechanistically responsible for the drooping of the leaves is the pulvinus. The stimulus is transmitted as an action potential from a stimulated leaflet to the leaflet's swollen base (pulvinus), and from there to the pulvini of the other leaflets, which run along the length of the leaf's rachis. The action potential then passes into the petiole, and finally to the large pulvinus at the end of the petiole, where the leaf attaches to the stem. The pulvini cells gain and lose turgor due to water moving in and out of these cells, and multiple ion concentrations play a role in the manipulation of water movement.
The mimosa's leaves, similar to Venus flytrap's trigger hairs, are hypersensitive to touch. [14] In line with the touch-sensing function used for tasks such as for defense or nutrient maintenance, these parts have mechanoreceptors linked to mechanosensitive channels that can conduct calcium ions and indirectly relative anions upon touch stimulation, giving rise to depolarization, the initiation of an action potential (AP). They also have voltage-sensitive potassium channels that promote hyperpolarization and turgor formation. Such sensitive plants fire all-or-nothing type APs, similar to those seen in animals.
This movement of folding inwards is energetically costly for the plant and also interferes with the process of photosynthesis. [15]
Mimosa pudica is native to the tropical Americas. It can also be found in Asian countries such as Singapore, Bangladesh, Thailand, India, Nepal, Indonesia, Taiwan, Malaysia, the Philippines, Vietnam, Cambodia, Laos, Japan, and Sri Lanka. It has been introduced to many other regions and is regarded as an invasive species in Tanzania, South and Southeast Asia, and many Pacific islands. [16] It is regarded as invasive in parts of Australia and is a declared weed in the Northern Territory, [17] and Western Australia although not naturalized there. [18] Control is recommended in Queensland. [19]
It has also been introduced to Uganda, Ghana, Nigeria, Seychelles, Mauritius and East Asia but is not regarded as invasive in those places. [16] In the United States, it grows in Louisiana, Florida, Hawaii, Tennessee, Virginia, Maryland, Puerto Rico, Texas, Alabama, Mississippi, North Carolina, Georgia, the territory of Guam, and the Virgin Islands. [20]
Mimosa pudica has several natural predators, such as the spider mite and mimosa webworm. Both of these insects wrap the leaflets in webs that hinder the responsive closing. Webbed leaves are noticeable as they become brown fossilized remnants after an attack. [21] The Mimosa webworm is composed of two generations that arise at different seasons. This makes prevention difficult and requires proper timing of insecticides to avoid aiding other predators. Once the larvae become steel-gray moths, they are harmless to the plant but lay more eggs. [22]
The species can be a weed for tropical crops, particularly when fields are hand-cultivated. Crops it tends to affect are corn, coconuts, tomatoes, cotton, coffee, bananas, soybeans, papaya, and sugar cane. Dry thickets may become a fire hazard. [9] In some cases, it has become a forage plant although the variety in Hawaii is reported to be toxic to livestock. [9] [23]
In addition, Mimosa pudica can change the physico-chemical properties of the soil it invades; total nitrogen and potassium, for example, have been seen to increase in significantly invaded areas. [24]
Thirty-six native Thai plant species were tested to see which conducted the most phytoremediation of arsenic-polluted soils caused by tin mines. Mimosa pudica was one of the four species that significantly extracted and bioaccumulated the pollutant into its leaves. [25] Other studies have found that Mimosa pudica extracts heavy metals such as copper, lead, tin, and zinc from polluted soils. This allows for the soil to gradually return to less toxic compositions. [26]
If nitrogen-fixing bacteria are present in the environment, Mimosa pudica may form root nodules for them to inhabit [27] . These bacteria are able to convert atmospheric nitrogen, which plants cannot use, into a form that plants can use. This trait is common among plants in the family Fabaceae. Nitrogen is a vital element for both plant growth and reproduction. Nitrogen is also essential for plant photosynthesis because it is a component of chlorophyll. Nitrogen fixation contributes nitrogen to the plant and to the soil surrounding the plant's roots. [28]
Nitrogen fixation is an adaptive trait that has transformed the parasitic relationship between the bacteria and plants into a mutualistic relationship. The shifting dynamics of this relationship are demonstrated by the corresponding improvement of various symbiotic characteristics in both Mimosa pudica and bacteria. These traits include enhanced "competitive nodulation, nodule development, intracellular infection, and bacteroid persistence". [29]
As much as 60% of the nitrogen found in Mimosa pudica can be attributed to the fixation of N2 by bacteria. Burkholderia phymatum STM815T and Cupriavidus taiwanensis LMG19424T are beta-rhizobial strains of diazotrophs that are highly effective at fixing nitrogen when coupled with M. pudica. Burkholderia is also shown to be a strong symbiont of Mimosa pudica in nitrogen-poor soils in regions like Cerrado and Caatinga. [12]
In cultivation, this plant is most often grown as an indoor annual but is also grown for groundcover. Propagation is generally by seed. Mimosa pudica grows most effectively in nutrient-poor soil that allows for substantial water drainage. However, this plant is also shown to grow in scalped and eroded subsoils. Typically, disrupted soil is necessary in order for M. pudica to become established in an area. Additionally, the plant is shade intolerant and frost-sensitive, meaning that it does not tolerate low levels of light or cold temperatures. Mimosa pudica does not compete for resources with larger foliage or forest canopy undergrowth. [11]
In temperate zones it must be grown under protection, where the temperature falls below 13 °C (55 °F).
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Mimosa pudica contains the toxic alkaloid mimosine, which has been found to also have antiproliferative and apoptotic effects. [30] The extracts of Mimosa pudica immobilize the filariform larvae of Strongyloides stercoralis in less than one hour. [31] Aqueous extracts of the roots of the plant have shown significant neutralizing effects in the lethality of the venom of the monocled cobra (Naja kaouthia). It appears to inhibit the myotoxicity and enzyme activity of cobra venom. [32]
Mimosa pudica demonstrates both antioxidant and antibacterial properties. This plant has also been demonstrated to be non-toxic in brine shrimp lethality tests, which suggests that M. pudica has low levels of toxicity. Chemical analysis has shown that Mimosa pudica contains various compounds, including "alkaloids, flavonoid C-glycosides, sterols, terenoids, tannins, saponin and fatty acids". [33] [34] The roots of the plant have been shown to contain up to 10% tannin. A substance[ which? ] similar to adrenaline has been found within the plant's leaves. Mimosa pudica's seeds produce mucilage made up of D-glucuronic acid and D-xylose. Additionally, extracts of M. pudica have been shown to contain crocetin-dimethylester, tubulin, and green-yellow fatty oils. A new class of phytohormone turgorines, which are derivatives of gallic acid 4-O-(β-D-glucopyranosyl-6'-sulfate), have been discovered within the plant. [11]
The nitrogen-fixing properties of Mimosa pudica contribute to a high nitrogen content within the plant's leaves. The leaves of M. pudica also contain a wide range of carbon to mineral content, as well as a large variation in 13C values. The correlation between these two numbers suggests that significant ecological adaptation has occurred among the varieties of M. pudica in Brazil. [28]
The roots contain sac-like structures that release organic and organosulfur compounds including SO2, methylsulfinic acid, pyruvic acid, lactic acid, ethanesulfinic acid, propane sulfinic acid, 2-mercaptoaniline, S-propyl propane 1-thiosulfinate, and thioformaldehyde, an elusive and highly unstable compound never before reported to be emitted by a plant. [35]
Wilhelm Pfeffer, a German botanist during the 19th century, used Mimosa in one of the first experiments testing plant habituation. [36] Further experimentation was done in 1965 when Holmes and Gruenberg discovered that Mimosa could distinguish between two stimuli, a water drop and a finger touch. Their findings also demonstrated that the habituated behavior was not due to fatigue since the leaf-folding response returned when another stimulus was presented. [36]
Electrical signaling experiments were conducted on Mimosa pudica, where 1.3–1.5 volts and 2–10 μC of charge acted as the threshold to induce closing of the leaves. [37] This topic was further explored in 2017 by neuroscientist Greg Gage who connected Mimosa pudica to Dionaea muscipula, better known as the Venus flytrap. Both plants had electrical wiring connecting them and were linked to an electrocardiogram. The results showed how causing an action potential in one plant led to an electrical response, causing both plants to respond. [38]
Experiments were made on how anesthetics for animals could affect Mimosa pudica. These experiments showed that anesthetics cause narcosis of the motor organs, which was observed by the application of volatile ether, chloroform, carbon tetrachloride, hydrogen sulfide, ammonia, formaldehyde, and other substances. [39] In a preclinical study, methanolic extract of Mimosa pudica showed significant antidiabetic and antihyperlipidemic activities in streptozotocin-induced diabetic rats. [40]
In 2018, two research groups from the Universities of Palermo (Italy) and Lugano (Switzerland) demonstrated the feasibility of using such plant as a building block for creating plant-based controllable two-color displays, exploiting air jets instead of electrical or touch-based stimulation. [41]
In a 2022 study in the journal Nature Communications, [42] researchers used simultaneous recordings of cytosolic Ca2+ and electrical signals to show that rapid changes in Ca2+ coupled with action and variation potentials trigger rapid movements in wounded M. pudica. Moreover, they found that disrupting cytosolic Ca2+ dynamics through pharmacological manipulation or CRISPR-Cas9 genome editing made M. pudica more vulnerable to herbivorous insect attacks. The findings suggest that these rapid movements based on propagating Ca2+ and electrical signals serve a protective role for the plant against insect herbivory.
The simplest form of learning is the ability of an organism to have a certain level of sensitivity to the environment that allows the organism to respond to potentially harmful stimuli as well as the capability to learn and filter out irrelevant stimuli (habituation) or increase the response due to a learned stimulus (sensitization). [43] Research done by scientist Monica Gagliano has shown habituation in Mimosa pudica. [44] In the experiment, M. pudica plants were repeatedly dropped until they stopped reacting to the stimulus. This seemed to show that the plants were learning that this disturbance did not hurt them, and ceased to react. However, to show that it was not that the plants were simply exhausted, some plants were exposed to a new stimulus (being shaken). These plants reacted fully to this stimulus, despite not reacting to the act of being dropped, suggesting the plants really had learned to recognize the "feeling" of being dropped. Further experiments showed that the plants continued to not react to dropping for at least 28 days, suggesting that they have the capacity for some form of memory associated with their habituation. [45]
In this experiment, researcher Monica Gagliano wanted to study if Mimosa plants in low-light conditions would have a greater potential for learning than those grown in high light. Plants that live in low-light environments have less of an opportunity for photosynthesis compared to plants that live in high-light environments where sunshine isn't a problem. When the Mimosa plant folds in its leaves as a defensive mechanism there is an energetic trade off, since folding its leaves reduces the amount of photosynthesis the Mimosa can perform during the closed period by 40%, but provides a rapid defensive mechanism against potentially harmful predators or external stimulation. [46] [47]
Since the low-light plants were already in low-energy environments and folding their leaves would be more energetically costly to the plant, researchers predicted the low-light plants would have adapted to have faster habitual learning capabilities so they could filter out unharmful stimuli to increase their energy production. Plants were either grown in high-light or low-light conditions. The plants were stimulated by being dropped from 15 cm for either a single drop or consecutive training sessions where the plants were repeatedly dropped. The plants were then shaken as a novel stimuli to test that the plants were suppressing their leaf folding reflex from habitual learning and not from exhaustion (dishabituation test). The first group was tested to see if short-term memory was enough for plants to modify their behaviour.
Regardless of what light group the plants were in, one drop was not enough for the plants to learn to ignore the stimulation. For the groups that were dropped repetitively, the plants stopped folding their leaves and were even fully open after a drop before the end of the trainings. The low-light plants learned faster to ignore the dropping stimulation than the high-light plants. When the plants were shaken, they responded immediately by folding their leaves, which suggests that the plants were not ignoring the dropping stimulation due to exhaustion. [44] This research suggests that the Mimosa has the capability for habitual learning and memory storage and that Mimosa plants grown in low-light conditions have faster learning mechanisms so they can reduce the amount of time their leaves are unnecessarily closed to optimize energy production. Further research suggests that both memory and habituation are present in wild Mimosa, and that they may be able to adjust habituation based leaf age and pollination requirements. [48] [49]
Given that plants lack a central nervous system, the means by which they send and store information is not obvious. There are two hypotheses for memory in Mimosa, neither of which has yet been generally accepted. The first is that when the plant is stimulated, it releases a surge of calcium ions that are sensed by the protein calmodulin. The relationship between the ions and proteins are thought to stimulate voltage-gated ion channels which cause electrical signals, which could be the base of plant long-term memory. The other hypothesis is that plant cells act similarly to neural cells by creating electrical gradients by opening and closing ion channels and passing it along cell junctions. The information passed along can control which genes are turned on and which genes are turned off, which could be a mode for long-term memory. [44]
Mimosa is a genus of about 600 species of herbs and shrubs, in the mimosoid clade of the legume family Fabaceae. Species are native to the Americas, from North Dakota to northern Argentina, and to eastern Africa as well as the Indian subcontinent and Indochina. The generic name is derived from the Greek word μῖμος (mimos), an "actor" or "mime", and the feminine suffix -osa, "resembling", suggesting its 'sensitive leaves' which seem to 'mimic conscious life'.
The Venus flytrap is a carnivorous plant native to the temperate and subtropical wetlands of North Carolina and South Carolina, on the East Coast of the United States. Although various modern hybrids have been created in cultivation, D. muscipula is the only species of the monotypic genus Dionaea. It is closely related to the waterwheel plant and the cosmopolitan sundews (Drosera), all of which belong to the family Droseraceae. Dionaea catches its prey—chiefly insects and arachnids—with a "jaw"-like clamping structure, which is formed by the terminal portion of each of the plant's leaves; when an insect makes contact with the open leaves, vibrations from the prey's movements ultimately trigger the "jaws" to shut via tiny hairs on their inner surfaces. Additionally, when an insect or spider touches one of these hairs, the trap prepares to close, only fully enclosing the prey if a second hair is contacted within (approximately) twenty seconds of the first contact. Triggers may occur as quickly as 1⁄10 of a second from initial contact.
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants.
In plant biology, thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however plant biologists have also found thigmotropic responses in flowering plants and fungi. This behavior occurs due to unilateral growth inhibition. That is, the growth rate on the side of the stem which is being touched is slower than on the side opposite the touch. The resultant growth pattern is to attach and sometimes curl around the object which is touching the plant. However, flowering plants have also been observed to move or grow their sex organs toward a pollinator that lands on the flower, as in Portulaca grandiflora.
Rapid plant movement encompasses movement in plant structures occurring over a very short period, usually under one second. For example, the Venus flytrap closes its trap in about 100 milliseconds. The traps of Utricularia are much faster, closing in about 0.5 milliseconds. The dogwood bunchberry's flower opens its petals and fires pollen in less than 0.5 milliseconds. The record is currently held by the white mulberry tree, with flower movement taking 25 microseconds, as pollen is catapulted from the stamens at velocities in excess of half the speed of sound—near the theoretical physical limits for movements in plants.
Mimosa tenuiflora, syn. Mimosa hostilis, also known as jurema preta, calumbi (Brazil), tepezcohuite (México), carbonal, cabrera, jurema, black jurema, and binho de jurema, is a perennial tree or shrub native to the northeastern region of Brazil and found as far north as southern Mexico, and the following countries: El Salvador, Honduras, Panama, Colombia and Venezuela. It is most often found in lower altitudes, but it can be found as high as 1,000 m (3,300 ft).
Thermotropism or thermotropic movement is the movement of an organism or a part of an organism in response to heat or changes from the environment's temperature. A common example is the curling of Rhododendron leaves in response to cold temperatures. Mimosa pudica also show thermotropism by the collapsing of leaf petioles leading to the folding of leaflets, when temperature drops.
Mimosa nuttallii, the Nuttall's sensitive-briar, catclaw brier, or sensitive brier, is an herbaceous perennial legume in the subfamily Mimosoideae native to the central United States. It has a trailing semi-woody vine covered with small recurved prickles that can be painful to bare skin.
Abscission is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a tail to evade a predator. In mycology, it is the liberation of a fungal spore. In cell biology, abscission refers to the separation of two daughter cells at the completion of cytokinesis.
In biology, thigmonasty or seismonasty is the nastic (non-directional) response of a plant or fungus to touch or vibration. Conspicuous examples of thigmonasty include many species in the leguminous subfamily Mimosoideae, active carnivorous plants such as Dionaea and a wide range of pollination mechanisms.
Mimosa pigra, commonly known as the giant sensitive tree, is a species of plant of the genus Mimosa, in the family Fabaceae.
Plant perception is the ability of plants to sense and respond to the environment by adjusting their morphology and physiology. Botanical research has revealed that plants are capable of reacting to a broad range of stimuli, including chemicals, gravity, light, moisture, infections, temperature, oxygen and carbon dioxide concentrations, parasite infestation, disease, physical disruption, sound, and touch. The scientific study of plant perception is informed by numerous disciplines, such as plant physiology, ecology, and molecular biology.
Mimosa diplotricha is a species of leguminous woody shrub native to the Neotropics. It is an invasive species and now has a pantropical distribution. It is commonly known as the giant sensitive plant, giant false sensitive plant, or nila grass.
A pulvinus may refer to a joint-like thickening at the base of a plant leaf or leaflet that facilitates growth-independent movement. Pulvinus is also a botanical term for the persistent peg-like bases of the leaves in the coniferous genera Picea and Tsuga. Pulvinar movement is common, for example, in members of the bean family Fabaceae (Leguminosae) and the prayer plant family Marantaceae.
Mimosa somnians, commonly known as dormideira, is a species of woody shrub in the genus Mimosa and the family Fabaceae. It is native to the Caribbean, Central America and South America. It is a short, low-lying shrub with minuscule thorns lining its stem-like hairs.
A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as such, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.
Biophytum sensitivum, also known as little tree plant, or Mukkootti is a species of plant in the genus Biophytum of the family Oxalidaceae. It is commonly found in Kerala, wet lands of Nepal, tropical India and in other Southeast Asian countries and is used for medicinal purposes in Nepal and India. The plant is also a common weed in tropical greenhouses, however, Biophytum sensitivum is particularly sensitive to spider mites. Investigations have been undertaken into the plant's chemistry, biological activities, and medicinal uses. Similarly to Mimosa pudica, the leaflets of Biophytum sensitivum are able to move rapidly in response to mechanical stimulation such as touch.
Plant cognition or plant gnosophysiology is the study of the learning and memory of plants, exploring the idea it is not only animals that are capable of detecting, responding to and learning from internal and external stimuli in order to choose and make decisions that are most appropriate to ensure survival. Over recent years, experimental evidence for the cognitive nature of plants has grown rapidly and has revealed the extent to which plants can use senses and cognition to respond to their environments. Some researchers claim that plants process information in similar ways as animal nervous systems. The implications are contested; whether plants have cognition or are simply animated objects.
A mechanoreceptor is a sensory organ or cell that responds to mechanical stimulation such as touch, pressure, vibration, and sound from both the internal and external environment. Mechanoreceptors are well-documented in animals and are integrated into the nervous system as sensory neurons. While plants do not have nerves or a nervous system like animals, they also contain mechanoreceptors that perform a similar function. Mechanoreceptors detect mechanical stimulus originating from within the plant (intrinsic) and from the surrounding environment (extrinsic). The ability to sense vibrations, touch, or other disturbance is an adaptive response to herbivory and attack so that the plant can appropriately defend itself against harm. Mechanoreceptors can be organized into three levels: molecular, cellular, and organ-level.
In plant biology, plant memory describes the ability of a plant to retain information from experienced stimuli and respond at a later time. For example, some plants have been observed to raise their leaves synchronously with the rising of the sun. Other plants produce new leaves in the spring after overwintering. Many experiments have been conducted into a plant's capacity for memory, including sensory, short-term, and long-term. The most basic learning and memory functions in animals have been observed in some plant species, and it has been proposed that the development of these basic memory mechanisms may have developed in an early organismal ancestor.