Stinging nettle

Appearance

Stinging nettle is a dioecious herbaceous perennial, 1 to 2 m 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 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 also bear many stinging hairs, whose tips come off when touched, transforming the hair into a needle that will inject several chemicals: acetylcholine, histamine, 5-HT, moroidin, leukotrienes, and possibly formic acid. This mixture of chemical compounds cause a painful sting or paresthesia from which the species derives its common name, as well as the colloquial names burn nettle, burn weed, burn hazel.

Distribution

Stinging nettles are 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. 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. In North America the stinging nettle is far less common than in northern Europe. The European subspecies has been introduced into North America as well as South America.

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

Habitat

Nettles are the exclusive larval food plant for several species of butterfly, such as the Peacock Butterfly or the Small Tortoiseshell, and are 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".

Food

Stinging nettle has a flavour similar to spinach and cucumber when cooked and is rich in vitamins A, 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 nettles in water or cooking will remove the stinging chemicals from the plant, which allows them to be handled and eaten without incidence of stinging. After 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, stinging nettle contains up to 25% protein, dry weight, which is high for a leafy green vegetable. The young leaves are edible and make a very good pot-herb. The leaves are also dried and may then be used to make a tisane, 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. In Nepal and the Kumaon & Garhwal region of Northern India, stinging nettle is known as Shishnu and Kandeli respectively. It is a very popular vegetable and cooked with Indian spices.

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

Defense

Anti-itch drugs, usually in the form of creams containing antihistaminics or hydrocortisone may provide relief from the symptoms of being stung by nettles. But due to the combination of chemicals involved other remedies may be required. Calamine lotion may be helpful. Many folk remedies exist for treating the itching including horsetail, leaf of dock, Jewelweed,, the underside of a fern, mud, saliva, or baking soda, oil and onions, and topical use of milk of magnesia. Lemon juice also works for treatment. Alternatively, one can simply ignore the stinging sensation and let it run its course.

Uses

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 is 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. This is done as a folk remedy for rheumatism, providing temporary relief from pain. The counter-irritant action to which this is often attributed can be preserved by the preparation of an alcoholic tincture which can be applied as part of a topical preparation, but not as an infusion, which drastically reduces the irritant action.

Nettle leaf is a herb that has a long tradition of use as an adjuvant remedy in the treatment of arthritis in Germany. Nettle leaf extract contains active compounds that reduce TNF-α and other inflammatory cytokines. It has been demonstrated that nettle leaf lowers TNF-α levels by potently inhibiting the genetic transcription factor that activates TNF-α and IL-1B in the synovial tissue that lines the joint.

Nettle is used in shampoo to control dandruff and is said to make hair more glossy, which is why some farmers include a handful of nettles with cattle feed.

Nettle root extracts have been extensively studied in human clinical trials as a treatment for symptoms of benign prostatic hyperplasia. These extracts have been shown to help relieve symptoms compared to placebo both by themselves and when combined with other herbal medicines.

Because it contains 3,4-divanillyltetrahydrofuran, certain extracts of the nettle are used by bodybuilders in an effort to increase free testosterone by occupying sex-hormone binding globulin

Cultural

In Great Britain the stinging nettle 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". The figure of speech "to grasp the nettle" probably originated from Aesop's fable "The Boy and the Nettle". In Sean 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.
In the German language, the idiom "sich in die Nesseln setzen", or to sit in nettles, means to get into trouble.
In Hungarian, the idiom "csalánba nem üt a mennykő" means bad things never happen to bad people.