 |  | ||||||||
Nettles are cosmopolitan weeds Figures of the family Urticaceae, found in temperate zones around the globe. Stinging nettle, Urtica dioica, is native to both Eurasia and North America. It is found across Canada from the Yukon and Northwest Territories to Newfoundland, and south throughout most of the United States into Mexico, but is less common in the Gulf and southeastern coastal states. It is found throughout Europe. Stinging nettle prefers shaded, moist areas along streams and deep, rich, undisturbed soils. Because of its stinging hairs, nettle may be a nuisance to recreationists. When present in thick stands, it may block livestock access to water. Young shoots can be used for a potherb or to make soup. Mature stems contain fiber that is used for weaving fine textiles. Nettle is a stoloniferous perennial, slow-spreading plant, reproducing by root and seed. Stems are usually 2 to 6 feet high. Leaves are opposite, dark green, narrowly ovate, sharply pointed at the tip, and bluntly rounded at the base, coarsely toothed, prominently veined, and with a short petiole. Leaves and stems are covered with fine hollow bristles. The small tip of the hair breaks with contact, producing a sharp point, and pressure against the bulbous reservoir at the base of the hair pushes fluid containing histamine and acetylcholine into the skin. Members of Urticaceae are usually wind-pollinated. Greenish, tassel-like, arising from the leaf axils,Urtica male and female flowers are found on separate plants. At anthesis, the inflexed stamens spring out, releasing pollen in a sudden burst.Pollination is generally from early May to late October in the United States, Canada, and mid-Europe, but as early as January or February in the west and south-central states. Pollen production is prolific. Because the grains are small, indistinct, and easily fragmented, nettle’s importance has been underestimated in the United States, although it has been reported as a moderately significant cause of hay fever in California, Oklahoma, and Canada. Using a Hirst spore trap, Hyde demonstrated counts rivaling that of grass pollen in Wales. It is felt to be an important inducer of pollinosis on the European continent and has been implicated in allergic asthma as well. Adapted from: Annals of Allergy, Richard Weber, MD, April 2003 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
 | |||||||||
Use of this web site indicates the user's agreement to be bound by the "Terms of Use." | |||||||||
 | | | | | | | | | |