About Urtica dioica subsp. sondenii (Simmons) Hyl.
This taxon is Urtica dioica subsp. sondenii (Simmons) Hyl., a subspecies of Urtica dioica, commonly called stinging nettle, burn-nettle, burn-weed, or burn-hazel. Urtica dioica is a dioecious, herbaceous, perennial plant. It reaches 0.9 to 2 metres (3 to 7 feet) tall during the summer, and dies back to the ground in winter. It has widely spreading bright yellow rhizomes and stolons, and the roots are also bright yellow. Its soft green leaves are 3 to 20 centimetres (1 to 6 inches) long, and grow oppositely on an erect, wiry, green stem. Leaves have a strongly serrated margin, a cordate base, and an acuminate tip, with a terminal leaf tooth that is longer than the adjacent lateral teeth. It produces numerous small greenish or brownish flowers arranged in dense axillary inflorescences. Leaves and stems are covered in many non-stinging hairs, and most subspecies of U. dioica also bear many stinging hairs, which are also called trichomes or spicules. When touched, the tips of these stinging hairs break off, turning the hair into a needle that injects several chemicals. These chemicals cause a painful sting or paresthesia, which gives the species its common names. Urtica dioica is considered native to Europe, much of temperate Asia, and western North Africa. It is abundant across northern Europe and much of Asia, and is usually found in rural countryside. It is less widespread in southern Europe and north Africa, where it is limited by its requirement for moist soil, but it remains common in these regions. It has been introduced to many other parts of the world. In North America, it is widely distributed across Canada and the United States, occurring in every province and state except Hawaii, and can also be found in the northernmost part of Mexico. It grows abundantly in the Pacific Northwest, especially in areas with high annual rainfall. The European subspecies of U. dioica has been introduced to Australia, North America, and South America. In Europe, stinging nettles are strongly associated with human habitation and buildings; their presence may indicate the site of a long-abandoned building, and can also signal that the soil is fertile. Elevated levels of phosphate and nitrogen in soil from human and animal waste create an ideal growing environment for nettles. Stinging nettles are the larval food source for several butterfly species in the Nymphalidae family, including the peacock butterfly, comma (Polygonia c-album), and small tortoiseshell. It is also eaten by the larvae of many moth species, 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 larvae of the ghost moth (Hepialus humuli). It is a known host for the pathogenic fungus Phoma herbarum. Stinging nettle occurs particularly as an understory plant in wetter environments, but it also grows in meadows. While it is nutritious, it is not widely eaten by wildlife or livestock, presumably because of its painful sting. It spreads via abundant seeds and through rhizomes, and is often able to survive and re-establish quickly after fire. As Old English stiðe, nettle is one of the nine plants invoked in the pagan Anglo-Saxon Nine Herbs Charm, a 10th-century record of traditional medicinal practice. Nettle was historically believed to be a galactagogue, a substance that promotes lactation. Urtication, the practice of flogging with nettles, is the process of deliberately applying stinging nettles to the skin to trigger inflammation. Used this way, nettle was considered a rubefacient, a substance that causes skin redness, and was used as a folk remedy to treat rheumatism. A 2000 study found that nettles are an effective therapy for relieving arthritis pain. In the European Union, nettle extract is approved for use as an insecticide, fungicide, and acaricide under Basic Substance regulations. As an insecticide, nettle extract can be used to control codling moth, diamondback moth, and spider mites. As a fungicide, it can be used to control Pythium root rot, powdery mildew, early blight, late blight, Septoria blight, Alternaria leaf spot, and grey mould.
