woad(redirected from Vitrum)
Also found in: Dictionary, Thesaurus.
See J. B. Hurry, The Woad Plant and Its Dye (1930, repr. 1974).
(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.