(Urtica dioica) Common nettle

Urtica dioica, often called common nettle, stinging nettle (although not all plants of this species sting) or nettle leaf, is a herbaceous perennialflowering plant in the family Urticaceae. Originally native to Europe, much of temperate Asia and western North Africa, it is now found worldwide.The species is divided into six subspecies, five of which have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation upon contact ("contact urticaria"). The plant has a long history of use as a source for traditional medicine, food, tea, and textile raw material in ancient societies.

Description
Urtica dioica is a dioecious, herbaceous, perennial plant, 1 to 2 m (3 to 7 ft) tall in the summer and dying down to the ground in winter. It has widely spreading rhizomes and stolons, which are bright yellow, as are the roots. The soft, green leaves are 3 to 15 cm (1 to 6 in) long and are borne oppositely on an erect, wiry, green stem. The leaves have a strongly serrated margin, a cordate base, and an acuminate tip with a terminal leaf tooth longer than adjacent laterals. It bears small, greenish or brownish, numerous flowers in dense axillary inflorescences. The leaves and stems are very hairy with non-stinging hairs, and in most subspecies, also bear many stinging hairs (trichomes or spicules), whose tips come off when touched, transforming the hair into a needle that can inject several chemicals causing a painful sting or paresthesia, giving the species its common names: stinging nettle, burn nettle, burn weed, or burn hazel.

Distribution
Urtica dioica is considered to be native to Europe, much of temperate Asia and western North Africa. It is abundant in northern Europe and much of Asia, usually found in the countryside. It is less widespread in southern Europe and north Africa, where it is restricted by its need for moist soil, but is still common. It has been introduced to many other parts of the world. In North America, it is widely distributed in Canada and the United States, where it is found in every province and state except for Hawaii, and also can be found in northernmost Mexico. It grows in abundance in the Pacific Northwest, especially in places where annual rainfall is high. The European subspecies has been introduced into Australia, North America and South America.

In Europe, nettles have a strong association with human habitation and buildings. The presence of nettles may indicate the site of a long-abandoned building. Human and animal waste may be responsible for elevated levels of phosphate and nitrogen in the soil, providing an ideal environment for nettles.

Ecology
Nettles are the exclusive larval food plant for several species of butterflies, such as the peacock butterfly, comma (Polygonia c-album), and the small tortoiseshell. It is also eaten by the larvae of some moths including angle shades, buff ermine, dot moth, the flame, the gothic, grey chi, grey pug, lesser broad-bordered yellow underwing, mouse moth, setaceous Hebrew character, and small angle shades. The roots are sometimes eaten by the larva of the ghost moth Hepialus humuli.

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.

Nettle sting mechanism and treatment
Urtica dioica produces its inflammatory effect on skin (stinging, burning sensation often called "contact urticaria") both by impaling the skin via spicules – causing mechanical irritation – and by biochemical irritants, such as histamine, serotonin, and choline, among other chemicals. Anti-itch drugs, usually in the form of creams containing antihistamines or hydrocortisone, may provide relief from nettle dermatitis. In Great Britain, the use of dock leaves on nettle stings is an established folk remedy, and revolves around the sap released from rubbing the leaf over affected areas of skin, which provides a cooling sensation. Docks and nettles regularly grow in the vicinity of each other due to both plants favouring the same soil conditions, and this may have aided the dock's popularity as a treatment for nettle stings.

The term, contact urticaria, has a wider use in dermatology, involving dermatitis caused by various skin irritants and pathogens.

Uses
Food
U. dioica has a flavour similar to spinach mixed with cucumber when cooked, and is rich in vitamins A and C, iron, potassium, manganese, and calcium. Young plants were harvested by Native Americans and used as a cooked plant in spring when other food plants were scarce. Soaking stinging nettles in water or cooking removes the stinging chemicals from the plant, which allows them to be handled and eaten without injury. After the stinging nettle enters its flowering and seed-setting stages, the leaves develop gritty particles called cystoliths, which can irritate the urinary tract. In its peak season, nettle contains up to 25% protein, dry weight, which is high for a leafy green vegetable. The leaves are also dried and may then be used to make a herbal tea, as can also be done with the nettle's flowers.

Nettles can be used in a variety of recipes, such as polenta, pesto, and purée. Nettle soup is a common use of the plant, particularly in Northern and Eastern Europe.

Nettles are sometimes used in cheesemaking, for example in the production of Cornish Yarg and as a flavouring in varieties of Gouda.

Nettles are used in Albania as part of the dough filling for the börek. The top baby leaves are selected and simmered, then mixed with other ingredients such as herbs and rice, before being used as a filling between dough layers. Similarly, in Greece the tender leaves are often used, after simmering, as a filling for hortopita, which is similar to spanakopita, but with wild greens rather than spinach for filling.

Competitive eating
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 60 cm (24 in) 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.

Drink
Nettle leaves are steeped in a concentrated sugar solution to extract the flavour. The leaves are then removed and a source of citric acid (usually lemon juice) is added to help preserve the cordial and add a tart flavour.

Commercially produced cordials are generally quite concentrated and are usually diluted by one part cordial to ten parts water – thus a 0.5 l (0.11 imp gal; 0.13 US gal) bottle of cordial would be enough for 5.5 litres (1.2 imp gal; 1.5 US gal) diluted. The high concentration of sugar in nettle cordial gives it a long shelf life.

Also, many recipes for alcoholic nettle beer are used, which is a countryside favourite in the British Isles.

Traditional medicine
U. dioica herb has been used in the traditional Austrian medicine internally (as tea or fresh leaves) to treat disorders of the kidneys and urinary tract, gastrointestinal tract, locomotor system, skin, cardiovascular system, hemorrhage, influenza, rheumatism, and gout.^[38]

As Old English stiðe, nettle is one of the nine plants invoked in the pagan Anglo-Saxon Nine Herbs Charm, recorded in the 10th century. Nettle was believed to be a galactagogue, a substance that promotes lactation.

Urtication, or flogging with nettles, is the process of deliberately applying stinging nettles to the skin in order to provoke inflammation. An agent thus used is known as a rubefacient (something that causes redness). This is done as a folk remedy for treatment of rheumatism. In Ecuador there are indigenous healers that use stinging nettles with the belief that they improve fatigue and circulation, by rubbing raw leaves or flogging the plant directly on the body.

Textiles and fibre
Nettle stems contain a bast fibre that has been traditionally used for the same purposes as linen and is produced by a similar retting process. Unlike cotton, nettles grow easily without pesticides. The fibres are coarser, however.

Historically, nettles have been used to make clothing for 2,000 years, and German Army uniforms were almost all made from nettle during World War I due to a potential shortage of cotton. More recently, companies in Austria, Germany, and Italy have started to produce commercial nettle textiles.

The fibre content in nettle shows a high variability and reaches from below 1% to 17%. Under middle-European conditions, stems yield typically between 45 and 55 dt / ha (decitons per hectare), which is comparable to flax stem yield. Due to the variable fibre content, the fibre yields vary between 0.2 and 7 dt / ha, but the yields are normally in the range between 2 and 4 dt / ha. Fibre varieties are normally cloning varieties and therefore planted from vegetative propagated plantlets. Direct seeding is possible, but leads to great heterogeneity in maturity.

Nettles may be used as a dye-stuff, producing yellow from the roots, or yellowish green from the leaves.
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https://en.wikipedia.org/wiki/Urtica_dioica