Mus′tard, species of Brassica, a genus belonging to the mustard family. The genus contains about 100 species of herbs, natives to north temperate regions. To the same genus belongs the cabbage, with its cauliflower and kale varieties, rape, rutabaga and common turnip. The true mustards are B. alba (white mustard), B. nigra (black mustard) and B. juncea (Chinese mustard). Table mustard is the flour formed from grinding the seeds, mostly from black mustard, though the white and Chinese mustards are also used. The white and black mustards often become widely distributed weeds. The large, soft, basal leaves of these forms are also frequently used for “greens.” The pale yellow flowers of the black mustard are very familiar; they bloom all summer on a many-branched plant from three to six feet high, the half-inch-long pods filled with dark-colored, pungent seeds. The seeds of the white mustard are light-colored, flowers yellow. In England mustard is planted for forage and cut before the seeds are ripe.
