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. Taxonomy
The taxonomy of Urtica species has been confused, and older sources are likely to use a variety of systematic names for these plants. Formerly, more species were recognised than are now accepted. However, at least six clear subspecies of U. dioica are described, some formerly classified as separate species:

U. dioica subsp. dioica (European stinging nettle), from Europe, Asia, and northern Africa, has stinging hairs. U. dioica subsp. galeopsifolia (fen nettle or stingless nettle), from Europe, does not have stinging hairs. U. dioica subsp. afghanica, from southwestern and central Asia, sometimes has stinging hairs or is sometimes hairless. U. dioica subsp. gansuensis, from eastern Asia (China), has stinging hairs. U. dioica subsp. gracilis (Ait.) Selander (American stinging nettle), from North America, has stinging hairs and is monoecious. U. dioica subsp. holosericea (Nutt.) Thorne (hoary stinging nettle), from North America, has stinging hairs and is monoecious.Other species names formerly accepted as distinct by some authors but now regarded as synonyms of one or other subspecies include U. breweri, U. californica, U. cardiophylla, U. lyalli, U. major, U. procera, U. serra, U. strigosissima, U. trachycarpa, and U. viridis.
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). It is a known host to the pathogenic fungus Phoma herbarum.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. Cultivation
Field
Sowing and planting
Three cultivation techniques can be used for the stinging nettle: 1) direct sowing, 2) growing seedlings in nurseries with subsequent transplantation and 3) vegetative propagation via stolons or head cuttings. Direct sowing: The seedbed should have a loose and fine structure, but should be reconsolidated using a packer roller imminently prior to sowing. Sowing time can be either in autumn or in spring. Seed density should be 6 kilograms/hectare with row spacing of 30 cm (12 in) and 42–50 cm in autumn and spring, respectively. The disadvantage of direct sowing is that it usually leads to incomplete plant coverage. This drawback can be mitigated by covering the seedbed with a transparent perforated foil in order to improve seed germination. Further, weed control can be problematic as the stinging nettle has a slow seedling development time.