1911 Encyclopædia Britannica/Nettle

NETTLE (O. Eng. netele, cf. Ger. Nessel), the English equivalent of Lat. Urtica, a genus of plants which gives its name to the natural order Urticaceae. It contains about thirty species in the temperate parts of both east and west hemispheres. They are herbs covered with stinging hairs, and with unisexual flowers on the same or on different plants. The male flowers consist of a perianth of four greenish segments enclosing as many stamens, which latter, when freed from the restraint exercised upon them by the perianth-segments while still in the bud, suddenly uncoil themselves, and in so doing liberate the pollen. The female perianth is similar, but encloses only a single seed-vessel with a solitary seed. The stinging hairs consist of a bulbous reservoir filled with. acrid fluid, prolonged into a long slender tube, the extremity of which is finely pointed. By this point the hair penetrates the skin and discharges its irritant contents beneath the surface. Nettle tops, or the very young shoots of the nettle, may be used as a vegetable like spinach; but from the abundance of crystals (cystoliths) they contain they are apt to be gritty, though esteemed for their antiscorbutic properties, which they do not possess in any exceptional degree. The fibre furnished by the stems of several species is used for cordage or paper-making. Three species of nettle are wild in the British Isles: Urtica dioica, the common stinging nettle, which is a hairy perennial with staminate and pistillate flowers in distinct plants; U. urens, which is annual and, except for the stinging hairs, glabrous, and has staminate and pistillate flowers in the same panicle; and U. pilulifera (Roman nettle), an annual with the pistillate flowers in rounded heads, which occurs in waste places in the east of England, chiefly near the sea—the more virulent of the British species. From their general presence in the neighbourhood of houses, or in spots where house refuse is deposited, it has been suggested that the nettles are not really natives, a supposition that to some extent receives countenance from the circumstance that the young shoots are very sensitive to frost. In any case they follow man in his migrations, and by their presence usually indicate a soil rich in nitrogen. The trailing subterranean root-stock renders the common nettle somewhat difficult of extirpation.