Urtica dioica

• 1. Introduction

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  Urtica dioica, the common stinging nettle, owes part of its modern fame to a boast made by one farmer to another in 1986. The two were neighbours, and each insisted that his own land had the worse nettle infestation. One of them finally said, "I'll eat any nettle of yours that's longer than mine." A plant that most people cross a field to avoid had just become a dare. That reversal fits the plant well. This perennial grows wild across much of the world, hurts anyone who brushes it, and yet has been eaten, worn, drunk, used as medicine and even used as punishment. How does a leaf deliver a sting like a needle? Why do people keep returning to something that hurts them? And what does a weed on the edge of a field reveal about the people who lived beside it?

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• 2. The Sting

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  Under a hand-lens, a nettle leaf looks less like foliage and more like a bed of tiny glass syringes. Five of the plant's six subspecies carry hollow stinging hairs, called trichomes, on both leaves and stems. When something touches one, the tip breaks off. The hair becomes a needle that pierces the skin and delivers a mix of chemicals. Histamine is the best known. Serotonin and acetylcholine are in the mixture too. The plant also bears many softer hairs that do not sting at all.

  The result is a burning, prickling feeling called contact urticaria, a form of contact dermatitis. Part of the pain is mechanical, from the spicules piercing the skin. The rest is chemical. For most people the discomfort fades by itself in about ten minutes. Some cases have lasted twelve hours or longer. Creams with antihistamines or hydrocortisone can help the most sensitive.

  Then there is the dock leaf. Docks, especially the broad-leaf dock, often grow in the same damp places as nettles. Folk tradition says rubbing a dock leaf on a sting cancels it. Nothing suggests any chemical effect. The relief may come from the rubbing itself, which distracts the nerves, or simply from believing it works.

  Cook the leaves, or soak them in water, and the stinging chemicals disappear. That small fact opens up everything else this plant has been used for.

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• 3. Where It Grows

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  In the Pacific Northwest of North America, where annual rainfall is high, nettles grow in great abundance. They are not originally from there. The species is native to Europe, much of temperate Asia and western North Africa, and the European subspecies has been carried to Australia, North America and South America. It now turns up in every Canadian province and every American state except Hawaii, and in the far north of Mexico.

  Nettles need moist soil. That is why they are abundant in northern Europe and much of Asia but less widespread across the drier south of Europe and in north Africa, where they are still common. They like understory shade in wet places, and they also appear in meadows. They spread by seed and by rhizomes, and they recover quickly after fire.

  In Europe, nettles follow people. A patch can mark the site of a building abandoned long ago. Human and animal waste enrich the ground with phosphate and nitrogen, and nettles thrive on both.

  Wildlife treats the plant differently from the way it treats most greens. Livestock and wild grazers mostly leave it alone, presumably because of the sting. Insects are another matter. Peacock butterflies, commas and small tortoiseshells lay their young on it, and a long list of moths, from the angle shades to the gothic, feed on its leaves. The ghost moth's larva eats the roots. The fungus Phoma herbarum also lives on it.

  In Britain there is a common belief that the Romans brought the nettle. The antiquarian William Camden mentioned the idea in his book Britannia of 1586. Yet Plant Atlas 2020 treats the plant as native. An excavation in 2011 supports that view. On Whitehorse Hill, Dartmoor, a Bronze Age burial cist dated to between 1730 and 1600 BC held beads and fragments of a sash woven from nettle fibre.

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• 4. Table and Contest

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  In spring, when other food plants are scarce, many Native American communities harvest young nettles and cook them. Cooked, the leaf tastes much like spinach. The plant also packs real nutrition. At peak season it can reach up to 25 percent protein by dry weight, a high figure for a leafy green.

  Older leaves are a different story. Once the plant flowers and sets seed, its leaves develop gritty particles called cystoliths, made of calcium carbonate. Many sources say these irritate the kidneys and urinary tract, but no medical evidence backs that claim. Boiling will not dissolve them. Fermentation, which uses acid, will.

  The kitchen uses are broad. Nettles go into polenta, pesto and purée, and soup is a staple in Northern and Eastern Europe. Cheesemakers use them for Cornish Yarg and to flavour some Goudas. In Albania, Montenegro, Serbia, North Macedonia and Bosnia and Herzegovina, the top baby leaves are simmered and mixed with herbs and rice as a filling for börek. Greek cooks fill hortopita the same way, a wild-greens cousin of spanakopita. Dried leaves and flowers make tea, and young shoots can be turned into an alcoholic drink.

  Then there is the raw version. Every year in Dorset, the World Nettle Eating Championship draws thousands of people. Each competitor receives stalks 60 centimetres long, strips off the leaves and eats them. Whoever finishes the most leaves in the allotted time wins.

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• 5. Healing and Punishment

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  Around the 10th century, an Anglo-Saxon text called the Nine Herbs Charm named nettle among nine plants it invoked. The Old English names were stiþe and wergulu. The charm belongs to the tradition of pagan medicine, and nettle was also thought to help nursing mothers produce milk, a property called galactagogue.

  The oddest remedy used the sting itself. Urtication means deliberately whipping or rubbing the skin with nettles to provoke inflammation. Because it reddens the skin, nettle was classed as a rubefacient, and people applied it against rheumatism. A study in 2000 found that nettles were an effective therapy for easing arthritis pain.

  The same practice has also been turned into a penalty. In 2010, indigenous justice systems in Ecuador used urtication to punish severe crimes. The convicted person was flogged with nettles in public, naked, while freezing water was thrown over them.

  The plant that eases pain in one setting was a tool of humiliation in another. Its meaning depends entirely on who is holding the stalk.

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• 6. Cloth From Stems

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  In Denmark, archaeologists have found nettle textiles from the Bronze Age. They show that people have made clothing from this plant for almost 3,000 years. The raw material is a bast fibre found in the stem, handled in much the same way as linen, through a similar retting process. Nettle has one advantage over cotton: it grows easily without pesticides. Its fibres are coarser, however.

  A popular story says that nearly all German Army uniforms in World War I were made of nettle, because cotton was short. Little evidence supports it. Real commercial production is more recent. Companies in Austria, Germany and Italy now make nettle textiles.

  Growing nettles for fibre is unpredictable. Fibre content varies from below 1 percent to 17 percent. Under middle-European conditions, stems typically yield between 45 and 55 decitons per hectare, comparable to flax. The usable fibre is far smaller, normally 2 to 4 decitons per hectare, though it can range from 0.2 to 7. Fibre varieties are usually clones, planted from propagated plantlets. Direct seeding works, but plants mature unevenly.

  Nettle also dyes. The roots give yellow, and the leaves give a yellowish green. Those bright yellow roots appear again in the plant's own description, among its spreading rhizomes.

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• 7. Garden and Field

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  Growers who want nettles on purpose have three options. The first is direct sowing, in autumn or spring, at 6 kilograms of seed per hectare. The result is usually patchy coverage, and weeds are hard to control because nettle seedlings develop slowly. A transparent perforated foil over the seedbed can help germination. The second option is raising seedlings in a nursery from mid-February or later and transplanting them from mid-April. Warm days at 30 degrees Celsius for 8 hours, followed by 16 cooler hours at 20, speed germination. The third is vegetative propagation, planting 10 cm stolons with several buds from mid-April, or rooting head cuttings. Greenhouse systems such as aeroponics may raise yields and reduce contamination.

  On the farm, nettle has a surprising job in the henhouse. Its carotenoids, especially lutein and zeaxanthin, colour egg yolks yellow. As little as 6.25 grams of dry nettle per kilogram of feed works as well as synthetic pigments, with no harm to the hens or the eggs. Ruminants avoid fresh nettle, but wilted or dry nettle is eaten readily. Nettle silage has a crude protein level close to ryegrass silage, at 171 grams per kilogram of dry matter against 177.

  In the European Union, nettle extract is permitted as an insecticide, fungicide and acaricide. It can be used against codling moth, diamondback moth and spider mites, and against powdery mildew, late blight and grey mould.

  Gardeners read nettles as a soil report, since they favour fertile, recently disturbed ground rich in phosphate and nitrate. Nettles also work as a compost activator, and steeped into a liquid fertiliser they supply magnesium, sulphur and iron. They tolerate soil rich in poultry droppings. They draw red admiral butterflies, whose caterpillars depend on them.

  Still, a nettle patch can become a problem weed, and mowing can make it denser. Persistent tilling cuts it back, as do herbicides such as 2,4-D and glyphosate.

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• 8. Names and Sayings

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  In 1753, Carl Linnaeus published the name Urtica dioica in Species Plantarum, and he is credited with it. The first word comes from a Latin word meaning sting. The second comes from the Greek for "of two houses", because male and female flowers grow on separate plants.

  The classification has been unsteady ever since. Until 2014, botanists broadly agreed that the nettles of the Americas were subspecies of U. dioica. That year a paper titled "Weeding the Nettles II" appeared in the journal Phytotaxa and showed these New World nettles are genetically distinct. They are now called Urtica gracilis. As of 2023, Plants of the World Online accepts that split, while the USDA PLANTS database and the Flora of North America still list it as a subspecies. Plants of the World Online recognises 11 subspecies or varieties of the species itself, including one from Europe with no stinging hairs.

  Language has absorbed the plant everywhere it grows. In Henry IV, Part 1, Hotspur says, "out of this nettle, danger, we pluck this flower, safety." The phrase "to grasp the nettle" probably comes from Aesop's fable "The Boy and the Nettle". Seán O'Casey's Juno and the Paycock quotes the moral: "Gently touch a nettle and it'll sting you for your pains/Grasp it as a lad of mettle and soft as silk remains." There may be real physics in it. A firm grip crushes the hairs flat, so they do not pierce so easily.

  German speakers say sich in die Nesseln setzen, to sit in nettles, when someone lands in trouble. Dutch uses netelige situatie for a predicament. French warns faut pas pousser mémé dans les orties, do not push granny into the nettles. The English word nettled, meaning irritated, comes from the plant.

  Germanic mythology linked Thor, god of thunder, with nettles, which gave rise to the saying that lightning will not strike into nettles. The idiom survives in Croatian, Hungarian, Serbian and many other Indo-European languages.

  Medicine borrowed the plant's name as well. The word urticaria, for hives, comes from the Latin Urtica, which in turn comes from urere, to burn.

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