Mustard seeds are the small round seeds of various mustard plants. The seeds are usually about 1 or 2 mm in diameter. Mustard seeds may be colored from yellowish white to black. They are important herbs in many regional foods. The seeds can come from three different plants: black mustard (Brassica nigra), brown Indian mustard (B. juncea), and white mustard (B. hirta/Sinapis alba).
Mustard seeds generally take three to ten days to germinate if placed under the proper conditions, which include a cold atmosphere and relatively moist soil. Mature mustard plants grow into shrubs.Mustard grows well in temperate regions. Major producers of mustard seeds include Canada, Hungary, Great Britain, India, Pakistan and the United States. Brown and black mustard seeds return higher yields than their yellow counterparts.
In Pakistan, rapeseed-mustard is the second most important source of oil, after cotton. It is cultivated over an area of 307,000 hectares with annual production of 233,000 tonnes and contributes about 17% to the domestic production of edible oil. Mustard seed is a rich source of oil and protein. The seed has oil as high as 46-48%, and whole seed meal has 43.6% protein.
Source
Wikipedia