nettle(redirected from Urtica)
Also found in: Dictionary, Thesaurus, Medical, Legal, Wikipedia.
nettle,common name for the Urticaceae, a family of fibrous herbs, small shrubs, and trees found chiefly in the tropics and subtropics. Several genera of nettles are covered with small stinging hairs that on contact emit an irritant (formic acid) which produces a skin rash sometimes called urticaria (see hiveshives
(urticaria), rash consisting of blotches or localized swellings (wheals) of the skin, caused by an allergic reaction (see allergy). The swelling is caused by distention of the skin capillaries and escape of serum and white cells into the skin and tissues.
..... Click the link for more information. ). The tropical American genus Urera is very powerful and sometimes dangerous. Stinging nettles in the United States include species of Urtica, widely distributed, and Laportea canadensis, a characteristic plant of eastern forests. L. gigas, the Australian nettle tree, reaches 90 ft (27.4 m) in height. Various plants of the family supply fiber, e.g., ramie, or China grass (Boehmeria nivea), native to SE Asia. Its valuable fiber is extremely strong, silky, and durable, but very difficult to extract. Because of the high quality of its various products (e.g., fabric, paper, and cordage) it has been cultivated experimentally in the United States and other countries. The young foliage of many temperate nettles supplies edible greens that are cooked like spinach. Various unrelated plants are sometimes also called nettles, e.g., the Old World nettle trees of the elm family and the prickly horse nettle of the nightshade family. The nettle family is classified in the division MagnoliophytaMagnoliophyta
, division of the plant kingdom consisting of those organisms commonly called the flowering plants, or angiosperms. The angiosperms have leaves, stems, and roots, and vascular, or conducting, tissue (xylem and phloem).
..... Click the link for more information. , class Magnoliopsida, order Urticales.
(Urtica) a genus of perennial or annual herbaceous plants of the family Urticaceae. The opposite leaves are dentate or have deep lobes and are usually covered with stinging hairs, as are the stems. The blossoms are very small, unisexual, tetramerous, and gathered in axillary, branchy, spicate inflorescences. The fruit is nutlike.
There are 40-50 species in the temperate zone of the northern hemisphere and, more rarely, in the southern hemisphere, as well as in the tropics. There are ten species in the USSR, found almost everywhere in shady and moist forests and shrub thickets and as a weed near dwellings and in gardens. The most widely distributed species are the perennial common stinging nettle (Urtica dioica) and the annual monoecious small nettle (U. urens).
The leaves of the common stinging nettle and, to a lesser degree, of the small nettle, contain vitamins C, K, B2, carotene (provitamin A), and the glycoside urticine and yield a green dye used in the pharmaceutical and food industries. Both species have therapeutic properties: the liquid extract of the leaves is used internally as an antihemorrhagic. The young shoots of the plant are used for soups and salads, as well as for fodder for cattle and domestic fowl. The stems are used to obtain fiber for making cord and coarse fabrics.
REFERENCEAtlas lekarstvennykh rastenii SSSR. Moscow, 1962.
T. V. EGOROVA