woad
woad
W0197900 (wōd)woad
(wəʊd)woad
(woʊd)n.
| Noun | 1. | woad - a blue dyestuff obtained from the woad plant |
| 2. | woad - any of several herbs of the genus Isatis |
| 单词 | woad | |||||||||||
| 释义 | woadwoadW0197900 (wōd)woad(wəʊd)woad(woʊd)n.
woadwoad,name for a perennial plant (Isatis tinctoria) of the family Cruciferae (or Brassicaceae; mustardmustard,common name for the Cruciferae, or Brassicaceae, a large family chiefly of herbs of north temperate regions. The easily distinguished flowers of the Cruciferae have four petals arranged diagonally ("cruciform") and alternating with the four sepals. ..... Click the link for more information. family) and for a blue dye obtained from its leaves. The plant is believed to be native to S Russia, but was in cultivation (and escaped) throughout Europe in early times. The pigment was obtained by fermentation and oxidation of a colorless glucoside, indican. Indican is also present in the leaves of the unrelated indigoindigo [Span.; from Lat.,=Indian], important blue dyestuff used in printing inks and for vat dyeing of cotton (see dye). It was anciently produced in India and was known in Egypt, probably c.1600 B.C. ..... Click the link for more information. , the other major blue vegetable dye plant. Although the dye obtained from indigo is superior in vividness of color, fastness, and ease of processing, woad growers and distributors of the Renaissance prohibited the sale of indigo in Europe for more than a century. In 1392 the Saxon town of Erfurt, Germany, had gained enough wealth through the woad trade to establish its own university. By the mid-17th cent., however, woad had been largely replaced by its successor—partly because of the low prices of indigo imports from the New World. Both woad and indigo have been eclipsed by the synthetic aniline dyes perfected in the late 19th cent. Woad was also extensively used for brilliant blue paint pigments. The ancients used it medicinally for ulcers and other ailments, and the early Britons painted their bodies with it. Woad 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 Capparales (or Brassicales), family Cruciferae (or Brassicaceae). BibliographySee J. B. Hurry, The Woad Plant and Its Dye (1930, repr. 1974). Woad(Isatis), a genus of plants of the family Cruciferae. Woad is an annual or biennial, less commonly perennial herb with alternate leaves and yellow flowers. The fruit is a monospermous hanging silicle. There are about 60 species of woad in Asia and Europe and 37 species in the USSR growing on flooded meadows, steppes, and dry rocky slopes, primarily in the Caucasus and Middle Asia and less commonly in the steppe zone of the European USSR and in Western and Eastern Siberia. The most common species is Isatis tinctoria, whose leaves yield a dark blue coloring (indigo) used to dye cloth. Its fruits contain 30 percent fatty oil. It was once widely cultivated in Western Europe as a dye plant, but this almost stopped when indigo began to be produced synthetically. Sometimes woad, mainly Isatis emar-ginata, is grown for fodder. woadWOAD
woad
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