question: Why do stinging nettles hurt so much and what do they do to you?
comment: The leaves themselves have small almost invisible "spikes" or stings on the surface of them. These are coated in methanoic (formic) acid which is what actually hurts. The acid itself is actually extremely similar to vinegar so you should get a similar feeling pouring vinegar into dot sized cut :D
passages: List of plants known as nettle
  
  Nettle is part of the English name of many plants with stinging hairs, particularly those of the genus "Urtica". It is also part of the name of plants which resemble "Urtica" species in appearance but do not have stinging hairs.
  
  Plants called "nettle" include:
  
  BULLET::::- ball nettle – "Solanum carolinense"
  
  BULLET::::- bull nettle
  
  BULLET::::- "Cnidoscolus stimulosus", bull nettle, spurge nettle
  
  BULLET::::- "Cnidoscolus texanus", Texas bull nettle
  
  BULLET::::- "Cnidoscolus urens", bull nettle
  
  BULLET::::- "Solanum elaeagnifolium", bull nettle, silver-leaf nettle, white horse-nettle
  
  BULLET::::- dead nettle, dumb nettle
  
  BULLET::::- "Lamium", particularly "Lamium album"
   Upon contact with skin the nettle causes a painful itch, hives, fever and chills, skin depressions and clamminess which can recur over 10 days to six months. About 1820, Jean Baptiste Louis Claude Theodore Leschenault de la Tour, the French botanist, described the pain caused by the nettle to be like "rubbing my fingers with hot iron". Jean Baptiste also suffered jaw muscle contractions so severe that he feared he had tetanus.
   Though plants with stinging hairs can cause pain and acute urticaria, only a few are seriously harmful. The genus "Dendrocnide" (stinging trees) has been said to cause the most pain, particularly the Australian "Dendrocnide moroides" (gympie-gympie). There are reports of dogs and horses being killed, and once of a human death. The researcher Marina Hurley reports being hospitalized after being stung by a dead leaf. Deaths are probably due to heart failure caused by pain and shock. "Urtica ferox" (tree nettle or ongaonga) is endemic to New Zealand. One recorded human death is known: a lightly clad young man died five hours after walking through a dense patch.
   This traditional interpretation was challenged in 2006 by research on "Urtica thunbergiana", the main species of "Urtica" present in Taiwan. In tests on rats, the long-lasting pain caused by stings was attributed to oxalic and tartaric acid, although a synergistic effect of the other components of the stinging hairs was not ruled out. Fu et al. concluded that "stinging hairs, although studied for a long time, are still mysterious, particularly concerning the mechanism of the skin reaction after being stung."
  
  Section::::Plants with stinging hairs.
  
  Section::::Plants with stinging hairs.:"Urtica".
   Many plants with stinging hairs belong to the genus "Urtica". Between twenty-four and thirty-nine species of flowering plants of the genus "Urtica" in the family Urticaceae fall into this category, with a cosmopolitan though mainly temperate distribution. They are mostly herbaceous perennial plants, but some are annual and a few are shrubby. The most prominent member of the genus "Urtica" is the stinging nettle, "Urtica dioica", native to Europe, Africa, Asia, and North America.
  
  Section::::Plants with stinging hairs.:Other Urticaceae.
  
  The family Urticaceae also contains some other plants with stinging hairs that are not members of the genus "Urtica". These include:
   The hazardous stinging tree ("Dendrocnide excelsa") is found in various locations throughout the park. This is a dangerous plant and physical contact with it should be avoided. The stems and leaves are coated with fine hairs which when imbedded in the skin cause severe pain and irritation for prolonged periods. "Smilax australis" (lawyer vine or wait-a-while) is another plant to be avoided as it has prickly climbing stems that are up to eight metres long and will catch in clothing or the skin.
   Other plants, such as opuntias, have hairs or spines that cause mechanical irritation, but do not inject chemicals. Stinging hairs occur particularly in the families Urticaceae, Loasaceae, Boraginaceae (subfamily Hydrophylloideae) and Euphorbiaceae. Such hairs have been shown to deter grazing mammals, but are no more effective against insect attack than non-stinging hairs. Many plants with stinging hairs have the word "nettle" in their English name, but may not be related to "true nettles" (the genus "Urtica").
   Section::::Habitat.
  
  "M. opercularis" can be found on oak, elm, and wild plum, among others, as well as many garden plants such as roses and ivy. It is distributed throughout the eastern United States between extreme southeastern Virginia and Florida, the southern United States, Mexico, and parts of Central America.
  
  Section::::Dangers and treatment of stings.
   If not treated promptly, the intense burning and stinging from an encounter with a nettle can last well over an hour, and could lead to cellulitis (a type of skin infection) or in rare cases, an allergic reaction. The secretions of the plant cause an intense burning sensation due to their highly acidic pH. The spines themselves provide a vehicle for the plants secretions to make it into the dermal and epidermal layers of the skin. Once the nettles themselves are removed from the skin, a moderately basic preparation such as baking soda mixed with water to form a paste is sufficient to neutralize the acidic secretions of the plant, thus stopping the painful burning and itching sensation.
   In Great Britain and Ireland, the stinging nettle ("U. dioica" subsp. "dioica") is the only common stinging plant and has found a place in several figures of speech in the English language. Shakespeare's Hotspur urges that "out of this nettle, danger, we pluck this flower, safety" ("Henry IV, part 1", Act II Scene 3). The figure of speech "to grasp the nettle" probably originated from Aesop's fable "The Boy and the Nettle". In Seán O'Casey's "Juno and the Paycock", one of the characters quotes Aesop "Gently touch a nettle and it'll sting you for your pains/Grasp it as a lad of mettle and soft as silk remains". The metaphor may refer to the fact that if a nettle plant is grasped firmly rather than brushed against, it does not sting so readily, because the hairs are crushed down flat and do not penetrate the skin so easily.
   BULLET::::- "Urtica taiwaniana" Taiwan
  
  BULLET::::- "Urtica thunbergiana" Japan, Taiwan
  
  BULLET::::- "Urtica triangularis"
  
  BULLET::::- "Urtica urens" (small nettle or annual nettle), Europe, North America
  
  BULLET::::- "Urtica urentivelutina"
  
  Section::::Ecology.
  
  Due to the stinging hairs, "Urtica" species are rarely eaten by herbivores, but rather provide shelter for insects, such as aphids, butterfly larvae, and moths.
  
  Section::::Uses.
  
  Fabric woven of nettle fiber was found in burial sites dating to the Bronze Age, and in clothing fabric, sailcloth, fishing nets, and paper by undeveloped communities. In New Zealand, "U. ferox" is classified among poisonous plants, most commonly upon skin contact.
   Different toxins may be involved. The stinging hairs of "Tragia volubilis", a South American member of the Euphorbiaceae, are capable of injecting a crystal of calcium oxalate. The stinging sensation is initially caused by the mechanical entry of the stiff hair into the skin, but is then intensified by the effect of the oxalate.
   Though several unrelated families of plants have stinging hairs, their structure is generally similar. A solid base supports a single elongated cell with a brittle tip. When the tip is broken, the exposed sharp point penetrates the skin and pressure injects toxins. The precise chemicals involved in causing pain and irritation are not yet fully understood.
  
  Section::::Structure and function of stinging hairs.
   In the UK, an annual World Nettle Eating Championship draws thousands of people to Dorset, where competitors attempt to eat as much of the raw plant as possible. Competitors are given stalks of the plant, from which they strip the leaves and eat them. Whoever strips and eats the most stinging nettle leaves in a fixed time is the winner. The competition dates back to 1986, when two neighbouring farmers attempted to settle a dispute about which had the worst infestation of nettles.
  
  Section::::Uses.:Beverage use.
   In 1804, Captain John Fulton of Grangehill married Catherine MacLellan, only daughter of the Rev. David Maclellan of Nettlehurst, Minister of Beith. They had two offspring, namely John and Isabella Fulton. Isabella married the Rev. Robert Crawford of Irongray. John's son was William Patrick Fulton. David Maclellan wrote articles under the name 'Urtica' (The scientific binomial for a stinging nettle is "Urtica dioica"). William Patrick of Roughwood obtained Nettlehirst from the Fultons and it later became part of the Giffin House estate.
   Stinging hairs may be defined as those with ability to inject a chemical substance through the skin of an animal causing irritation or pain. Since some glandular hairs can cause irritation merely by contact, the difference between "stinging hairs" and "irritating hairs" is not always clear. For example, the hairs of "Mucuna" species are described in both ways. Some species of "Mucuna" have sharply tipped hairs, in which the upper part easily breaks off, whereas other species have hairs that are blunter. In those subspecies of "Urtica dioica" that have stinging hairs (stinging nettles), these also have a point that easily breaks off, allowing the irritants in the cell below to enter through the skin. Being stung in this way has been shown to deter grazing mammals, such as rabbits, and even large herbivores such as cows. Many plant species respond to physical damage by producing a higher density of trichomes of all kinds.
   BULLET::::- "Dendrocnide" spp.
  
  BULLET::::- "Dendrocnide excelsa" (giant stinging tree)
  
  BULLET::::- "Dendrocnide moroides" (gympie-gympie)
  
  BULLET::::- "Dendrocnide peltata" (stinging tree, "jelaton")
  
  BULLET::::- "Girardinia diversifolia" (synonym: "G. leschenaultiana") (Nilgiri nettle, Himalayan giant nettle), source of allo fibre
  
  BULLET::::- "Laportea canadensis" (wood nettle)
  
  BULLET::::- "Urera" spp.
  
  BULLET::::- "Urera baccifera" (nettle tree)
  
  BULLET::::- "Urera tenax"
  
  Section::::Plants with stinging hairs.:Other families.
  
  There are also plants with stinging hairs that are unrelated to the Urticaceae:
  
  BULLET::::- Boraginaceae: Hydrophylloideae
  
  BULLET::::- "Phacelia malvifolia" (stinging phacelia)
  
  BULLET::::- "Wigandia" spp.
  
  BULLET::::- Euphorbiaceae
  
  BULLET::::- "Cnidoscolus" spp.
  
  BULLET::::- "Cnidoscolus stimulosus" (bull nettle or spurge nettle)
  
  BULLET::::- "Cnidoscolus urens" (mala mujer)
   In ethnoveterinary medicine, the flowering stems of "Digitalis obscura" were traditionally used to promote wound healing and treat toothaches in animals. It is one of twenty-three species traditionally used in Granada to treat trauma or poisoning in animals.
  
  Section::::Usage.:Toxicity.
  
  All parts of "Digitalis obscura" are poisonous if ingested raw, including the roots and seeds. The most potent parts of the plant are the upper leaves.
   BULLET::::- false nettle – "Boehmeria"
  
  BULLET::::- flame nettle – "Coleus"
  
  BULLET::::- hedge nettle – "Stachys"
  
  BULLET::::- hemp nettle – "Galeopsis"
  
  BULLET::::- horse nettle:
  
  BULLET::::- "Agastache urticifolia" – horse-nettle
  
  BULLET::::- "Solanum carolinense" – ball-nettle, Carolina horse-nettle
  
  BULLET::::- "Solanum dimidiatum" – western horse-nettle, robust horse-nettle
  
  BULLET::::- "Solanum elaeagnifolium" – bull nettle, silver-leaf nettle, white horse-nettle
  
  BULLET::::- "Solanum rostratum" – horse-nettle
  
  BULLET::::- nettle tree or tree nettle:
  
  BULLET::::- "Celtis"
  
  BULLET::::- Various species of the genus "Dendrocnide"
  
  BULLET::::- "Urera baccifera"
  
  BULLET::::- "Urtica ferox"
  
  BULLET::::- nilgiri nettle, Himalayan giant nettle - "Girardinia diversifolia"
  
  BULLET::::- painted nettle – "Coleus blumei"
  
  BULLET::::- rock nettle – "Eucnide"
   The Atlantic sea nettle is a bell-shaped invertebrate, usually semi-transparent and with small, white dots and reddish-brown stripes. Sea nettles without stripes have a bell that appears white or opaque. The sea nettle's sting is rated from "moderate" to "severe" and can be noxious to smaller prey; it is not, however, potent enough to cause human death, except by allergic reaction. While the sting is not particularly harmful, it can cause moderate discomfort to any individual stung. The sting can be effectively neutralized by misting vinegar over the affected area. This keeps unfired nematocysts from firing and adding to the discomfort.
   In the United Kingdom the plant is often found growing near stinging nettles and the underside of the dock leaf, squeezed to extract a little juice, can be rubbed on the skin to counteract the itching caused by brushing against a nettle plant. 
  
  Section::::Usage.:History.
  
  In George Eliot's "Adam Bede", set in the early 19th century, broad dock leaves were used to wrap farmhouse butter.
  
  Section::::Usage.:Host plant.
   The shrub can grow to a height of 3 m (9.8 ft) with the base of the stem reaching 12 cm (4.7 in) in thickness. The pale green leaves are very thin like a membrane, the surface of the leaf, stems and stalks are covered in stiff stinging hairs can grow up to long. These spines are prominent along the salient mid-vein and leaf margin. The leaves range from in width and in length, these are oppositely arranged and there are two stipules per node. The leaf shape is ovulate-triangulate with a serrated leaf margin each bearing a spine of up to . The spines covering the leaf surface, stem and stalk are generally no larger than in length, the spines on the older darker bark are smaller and softer, these don't cause a sting. This nettle is winter deciduous in cold climates, evergreen in mild climates and can lose its leaves in drought conditions if it is growing in shallow soils.
   Stinging nettle is particularly found as an understory plant in wetter environments, but it is also found in meadows. Although nutritious, it is not widely eaten by either wildlife or livestock, presumably because of the sting. It spreads by abundant seeds and also by rhizomes, and is often able to survive and re-establish quickly after fire.
  
  Section::::Nettle sting mechanism and treatment.
   Each sea nettle tentacle is coated with thousands of microscopic cnidocytes; in turn, every individual cnidocyte has a "trigger" (cnidocil) paired with a capsule containing a coiled stinging filament. Upon contact, the cnidocil will immediately initiate a process which ejects the venom-coated filament from its capsule and into the target. This will inject toxins capable of killing smaller prey or stunning perceived predators. On humans, this will most likely cause a nonlethal, but nevertheless painful rash typically persisting for about 20 minutes. Some earlier cases of sea nettle stings from the Philippines reportedly had more severe effects: one account describes a sting causing vascular insufficiency, and another mononeuritis.
   Stinging plant
  
  A stinging plant or a plant with stinging hairs is a plant with hairs (trichomes) on its leaves or stems that are capable of injecting substances that cause pain or irritation.
  