question: How to plants that react to touch like the Venus Flytrap of the Sensitive Mimosa work?
comment: If I remember correctly, for the Venus flytrap, there’s sensitive hairs on at the ‘clamping’ area. It takes lots of energy though, so when one hair is triggered, there’s a timing mechanism that’s set off. Only if multiple hairs are ‘moved’ within a set timeframe does the plant exert substantial energy to close the trap. Not an explanation on the cellular scale though, hope someone can explain further too!
passages: Some plants are capable of rapid movement: the so-called "sensitive plant" ("Mimosa pudica") responds to even the slightest physical touch by quickly folding its thin pinnate leaves such that they point downwards, and carnivorous plants such as the Venus flytrap ("Dionaea muscipula") produce specialized leaf structures that instantaneously snap shut when touched or landed upon by insects. In the Venus flytrap, touch is detected by cilia lining the inside of the specialized leaves, which generate an action potential that stimulates motor cells and causes movement to occur.
  
  In plants, the mechanism responsible for adaptation is signal transduction. Adaptive responses include:
   Nastic movements results from differential cell growth (e.g. epinasty and hiponasty), or from changes in turgor pressure within plant tissues (e.g., nyctinasty), which may occur rapidly. A familiar example is thigmonasty (response to touch) in the Venus fly trap, a carnivorous plant. The traps consist of modified leaf blades which bear sensitive trigger hairs. When the hairs are touched by an insect or other animal, the leaf folds shut. This mechanism allows the plant to trap and digest small insects for additional nutrients. Although the trap is rapidly shut by changes in internal cell pressures, the leaf must grow slowly to reset for a second opportunity to trap insects.
   Section::::Plant physiology.:Plant hormones.
  
  Plants are not passive, but respond to external signals such as light, touch, and injury by moving or growing towards or away from the stimulus, as appropriate. Tangible evidence of touch sensitivity is the almost instantaneous collapse of leaflets of "Mimosa pudica", the insect traps of Venus flytrap and bladderworts, and the pollinia of orchids.
   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. 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.
   Section::::Examples of plants exhibiting thigmonasty.:In the Droseraceae.
  
  The Venus Flytrap ("Dionaea muscipula") presents a spectacular example of thigmonasty; when an insect lands on a trap formed by two curved lobes of a single leaf, the trap rapidly switches from an open to a closed configuration. Investigators have observed an action potential and changes in leaf turgor that accompany the reflex; they trigger the rapid elongation of individual cells. The common term for the elongation is acid growth although the process does not involve cell division.
  
  Section::::Examples of plants exhibiting thigmonasty.:In the Fabaceae.
   The Venus flytrap is a carnivorous plant that catches its prey with a trapping structure formed by the terminal portion of each of the plant's leaves, which is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap prepares to close, snapping shut only if a second contact occurs within approximately twenty seconds of the first strike. The requirement of redundant triggering in this mechanism serves as a safeguard against wasting energy by trapping objects with no nutritional value, and the plant will only begin digestion after five more stimuli to ensure it has caught a live bug worthy of consumption.
   A plant's concomitant reactive behavior is mediated by phytochromes, kinins, hormones, antibiotic or other chemical release, changes of water and chemical transport, and other means. These responses are generally slow, taking at minimum a number of hours to accomplish, and can best be observed with time-lapse cinematography, but rapid movements can occur as well. Plants respond to volatile signals produced by other plants. Jasmonate levels also increase rapidly in response to mechanical perturbations such as tendril coiling.
   Section::::Chemical ecology of plants.:Interactions with microorganisms.
  
  Plants interact also with micro-organisms. For this to become possible the microbes have to establish an interface between them and the plant, by growing into the plant through its surface. To do so, the microbes need to break the protective hydrophobic waxy layer on the plant’s surface. To do this, the micro-organisms secrete special fluids which break down the fats from the cuticle.
  
  Section::::Chemical ecology of plants.:Growth in plants.
   Plants respond to parasite attack with a series of chemical defences, such as polyphenol oxidase, under the control of the jasmonic acid-insensitive (JA) and salicylic acid (SA) signalling pathways. The different biochemical pathways are activated by different attacks, and the two pathways can interact positively or negatively. In general, plants can either initiate a specific or a non-specific response. Specific responses involve recognition of a parasite by the plant's cellular receptors, leading to a strong but localised response: defensive chemicals are produced around the area where the parasite was detected, blocking its spread, and avoiding wasting defensive production where it is not needed. Nonspecific defensive responses are systemic, meaning that the responses are not confined to an area of the plant, but spread throughout the plant, making them costly in energy. These are effective against a wide range of parasites. When damaged, such as by lepidopteran caterpillars, leaves of plants including maize and cotton release increased amounts of volatile chemicals such as terpenes that signal they are being attacked; one effect of this is to attract parasitoid wasps, which in turn attack the caterpillars.
   Section::::See also.
  
  BULLET::::- Exotic plants
  
  BULLET::::- "Mimosa pigra"
  
  BULLET::::- Venus flytrap
  
  Section::::External links.
  
  BULLET::::- A list of notable chemical compounds found in "Mimosa pudica"
  
  BULLET::::- View occurrences of "Mimosa pudica" in the Biodiversity Heritage Library
  
  BULLET::::- "Sensitive Plant" page by Dr. T. Ombrello
  
  BULLET::::- Fact Sheet from the Queensland (Australia) Department of Agriculture, Fisheries and Forestry
  
  BULLET::::- Page about nyctinasty and leaf movement of "Mimosa pudica" by John Hewitson
  
  BULLET::::- Indiana.edu "Plants in motion" videos of "Mimosa pudica":
   Section::::Physical irritant contact dermatitis.:Plants.
  
  Many plants cause irritant contact dermatitis through their spines or irritant hairs. Some plants such as the buttercup, spurge, and daisy act by chemical means. The sap of these plants contains a number of alkaloids, glycosides, saponins, anthraquinones, and (in the case of plant bulbs) irritant calcium oxalate crystals - all of which can cause crystal irritant contact dermatitis.
   Speed of closing can vary depending on the amount of humidity, light, size of prey, and general growing conditions. The speed with which traps close can be used as an indicator of a plant's general health. Venus flytraps are not as humidity-dependent as are some other carnivorous plants, such as "Nepenthes", "Cephalotus", most "Heliamphora", and some "Drosera".
   Section::::Flower development.:Floral fragrance.
  
  Plants use floral form, flower, and scent to attract different insects for pollination. Certain compounds within the emitted scent appeal to particular pollinators. In "Petunia" "hybrid"a, volatile benzenoids are produced to give off the floral smell. While components of the benzenoid biosynthetic pathway are known, the enzymes within the pathway, and subsequent regulation of those enzymes, are yet to be discovered. 
   Thigmonastic movements, those that occur in response to touch, are used as a defense in some plants. The leaves of the sensitive plant, "Mimosa pudica", close up rapidly in response to direct touch, vibration, or even electrical and thermal stimuli. The proximate cause of this mechanical response is an abrupt change in the turgor pressure in the pulvini at the base of leaves resulting from osmotic phenomena. This is then spread via both electrical and chemical means through the plant; only a single leaflet need be disturbed. This response lowers the surface area available to herbivores, which are presented with the underside of each leaflet, and results in a wilted appearance. It may also physically dislodge small herbivores, such as insects.
   Section::::Chemical mechanisms of enemy attraction.
   The tendrils of plants are especially sensitive to airborne volatile organic compounds. Parasites such as dodder make use of this in locating their preferred hosts and locking on to them. The emission of volatile compounds is detected when foliage is browsed by animals. Threatened plants are then able to take defensive chemical measures, such as moving tannin compounds to their foliage. (See Plant perception).
   Natural enemies can distinguish between mechanical tissue damage, which might occur during a number of events other than herbivory, and damage that is the direct result of insect feeding behavior. The presence of herbivore saliva or regurgitant mediates this differentiation and the resulting chemical pathway leads to a significantly stronger natural enemy response than mechanical damage could. The reliability of HIPVs in broadcasting the location of prey means that for many foraging enemies, induced plant volatiles are more attractive than even the odors emitted by the prey insect itself.
  
  Section::::Chemical mechanisms of enemy attraction.:Local and systemic signals.
   When an insect or spider crawling along the leaves contacts a hair, the trap prepares to close, snapping shut only if another contact occurs within approximately twenty seconds of the first strike. Triggers may occur if one-tenth of the insect is within contact. The requirement of redundant triggering in this mechanism serves as a safeguard against wasting energy by trapping objects with no nutritional value, and the plant will only begin digestion after five more stimuli to ensure it has caught a live bug worthy of consumption.
   Flytraps show a clear example of memory in plants, the plant knows if its hair has been touched, and remembers that for a few seconds. The plant then recalls that incident if a second touch happens during that time frame, and closes. After closing, the flytrap counts additional stimulations of the trigger hairs, to five total, to start the production of digesting enzymes.
  
  Section::::Carnivory.:Digestion.
   Thigmonasty differs from thigmotropism in that nastic motion is independent of the direction of the stimulus. For example, tendrils from a climbing plant are thigmotropic because they twine around any support they touch, responding in whichever direction the stimulus came from. However, the shutting of a venus fly trap is thigmonastic; no matter what the direction of the stimulus, the trap simply shuts (and later possibly opens).
   BULLET::::- Latunde-Dada, A. O. (2001). Colletotrichum: Tales of forcible entry, stealth, transient confinement and breakout. "Molecular Plant Pathology", "2"(4), 187–198. https://doi.org/10.1046/j.1464-6722.2001.00069.x
   When plants are attacked they can manifest physical changes, such as strengthening their cell walls, depositing callose, or forming cork. They can also manifest biochemical changes, including the production of volatile organic compounds (VOCs) or the up-regulation of genes producing other defensive enzymes, many of which are toxic to pathogens or herbivores. Salicylic acid (SA) and its derivatives, like methyl salicylate, are VOCs which help plants to recognize infection or attack and to organize other plant defenses, and exposure to them in animals can cause pathological processes. Terpenoids are produced constituently in many plants or are produced as a response to stress and act much like methyl salicylate. Jasmonates are a class of VOCs produced by the jasmonic acid (JA) pathway. Jasmonates are used in plant defense against insects and pathogens and can cause the expression of proteases, which defend against insect attack. Plants have many ways to react to attack, including the production of VOCs, which studies report can coordinate defenses among plants connected by mycorrhizal networks.
   BULLET::::- "Sesbania"
  
  BULLET::::- "Sesleria"
  
  BULLET::::- "Setaria"
  
  BULLET::::- "Shepherdia"
  
  BULLET::::- "Shibataea"
  
  BULLET::::- "Shortia"
  
  BULLET::::- "Sibiraea"
  
  BULLET::::- "Sidalcea"
  
  BULLET::::- "Sideritis"
  
  BULLET::::- "Silene" (campion)
  
  BULLET::::- "Silphium"
  
  BULLET::::- "Silybum"
  
  BULLET::::- "Simmondsia" (jojoba)
  
  BULLET::::- "Sinningia"
  
  BULLET::::- "Sinocalycanthus"
  
  BULLET::::- "Sinofranchetia"
  
  BULLET::::- "Sinojackia"
  
  BULLET::::- "Sinowilsonia"
  
  BULLET::::- "Sisyrinchium"
  
  BULLET::::- "Skimmia"
  
  BULLET::::- "Smilacina"
  
  BULLET::::- "Smilax"
  
  BULLET::::- "Smithiantha"
  
  BULLET::::- "Smyrnium"
  
  BULLET::::- "Sobralia" an orchid genus
  
  BULLET::::- "Solandra"
  
  BULLET::::- "Solanum" (potato, nightshade)
  
  BULLET::::- "Soldanella" (snowbell)
  
  BULLET::::- "Soleirolia"
  
  BULLET::::- "Solenopsis"
  
  BULLET::::- "Solenostemon"
  
  BULLET::::- "Solidago" (goldenrod)
  
  BULLET::::- "Solidaster" (supposedly hybrid genus; see "Solidago")
  
  BULLET::::- "Sollya"
  
  BULLET::::- "Sonerila"
  
  BULLET::::- "Sophora"
  
  BULLET::::- "Sophrolaeliocattleya" (trigeneric hybrid orchid)
  
  BULLET::::- "Sophronitis" (an orchid genus)
  
  BULLET::::- "Sorbaria"
   At anthesis, as is common in angiosperms, both male and female "Chamaerops humilis" plants attract their pollinators with chemical compounds, but an unusual feature is that their scents are released by the leaves, and not by the flowers. Towards the end of anthesis, weevils leave the plant and seek a new host plant, again either male or female.
   Priming occurs when a plant's defenses are activated before an attack. Studies have shown that priming of plant defenses among plants in mycorrhizal networks may be activated by the networks, as they make it easier for these infochemicals to propagate among the connected plants. The defenses of uninfected plants are primed by their response via the network to the terpenoids produced by the infected plants. AM networks can prime plant defensive reactions by causing them to increase the production of terpinoids.
  