Brassica nigra, black mustard, is an annual herbaceous plant in the Brassicaceae (the cabbage or mustard family) that originated in the Middle East and is now widely cultivated as a primary source of the mustard seeds used in making the condiment sauce, table mustard. (Other species that are known as mustard and are used to make the condiment include B. juncea var. juncea (brown, Indian, or Dijon mustard) and B. carinata (Ethiopian mustard).
The black mustard plant grows up to 2 m (a little over 6 ft), with many branches. The lower leaves are dentate (toothed), pinnatifid (deeply lobed) or lyrate (deeply lobed, but with an enlarged terminal lobe and smaller lateral lobes), and are often hairy, at least on the underside. Upper leaves on flowering stems are narrow and oblong. In contrast to many Brassica species, the leaves are little if at all glaucous (waxy). The yellow, four-parted and cross-shaped flowers, occur in many racemes (spike-like cluster) and produce 4-sided siliques—capsular fruit that dehisces (splits open) when mature—that may be up to 2.5 cm (1 in) long. Each silique contains 2 to 12 or more reddish brown to black round seeds. A single plant may produce thousands of seeds, which must be harvested by hand or mechanically before they fully ripen, because the siliques spontaneously split and disperse the seeds when they are mature.
Young mustard plants and leaves may be eaten as a salad or cooked green, but the plant is primarily used for its seeds. Black mustard seeds are typically ground and mixed with water or vinegar to make prepared mustard, which is one of the most important condiments in European and North American cuisine. It is used as an ingredient in numerous sauces and salad dressings, and is popular for eating with sausages (such as the German bratwurst and American hot dogs). Mustard seeds, which can be a skin irritant, also have antibacterial properties, and have been used to treat rheumatism. Black mustard is one of several Brassica species that are used as winter cover crops.
The FAO estimates that in 2010, total commercial production of mustard seed (of all species) was 59.1 million metric tons worldwide, harvested from 31.7 million hectares. Canada and Nepal were the leading producers, together accounting for 321 thousand metric tons, followed by the Ukraine, Myanmar, the Russian Federation, and the U.S.
With fast growth and prolific seed production, black mustard has often escaped cultivation and is widespread as a weed in agricultural settings. Black mustard has been introduced and naturalized in much of the U.S. and Canada, and is classified as invasive in New Zealand, Hawaii, and the off-shore islands of Chile.
(Bailey et al. 1976, FAOSTAT 2012, Hedrick 1919, USDA 2012, USFS 2012, van Wyk 2005.)
