|Urtica dioica subsp. var.||Big string nettle, Common nettle, Stinging nettle|
Stinging nettle or common nettle, Urtica dioica, is a herbaceous perennial flowering plant, native to Europe, Asia, northern Africa, and North America, and is the best-known member of the nettle genus Urtica.
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 4-merous flowers in dense axillary inflorescences. The leaves and stems are very hairy with non-stinging hairs and also bear many stinging hairs (trichomes), whose tips come off when touched, transforming the hair into a needle that will inject several chemicals that sting. The pain and itching from a nettle sting can last from only a few minutes to as long as a week.
Pests and diseases
The taxonomy of stinging nettles 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, there are at least five clear subspecies, some formerly classified as separate species:
- U. dioica subsp. dioica (European stinging nettle). Europe, Asia, northern Africa.
- U. dioica subsp. galeopsifolia (fen nettle or stingless nettle). Europe. (Sometimes known as Urtica galeopsifolia)
- U. dioica subsp. afghanica. Southwestern and central Asia. (Gazaneh in Iran)
- U. dioica subsp. gansuensis. Eastern Asia (China).
- U. dioica subsp. gracilis (Ait.) Selander (American stinging nettle). North America.
- U. dioica subsp. holosericea (Nutt.) Thorne (hairy nettle). North America.
Other species names formerly accepted as distinct by some authors but now regarded as synonyms of U. dioica include U. breweri, U. californica, U. cardiophylla, U. lyalli, U. major, U. procera, U. serra, U. strigosissima, U. trachycarpa, and U. viridis. Other vernacular names include tall nettle, slender nettle, California nettle, jaggy nettle, burning weed, fire weed and bull nettle (a name shared by Cnidoscolus texanus and Solanum carolinense).