Mustard seeds are the small round seeds of various mustard plants. The seeds are usually about 1 to 2 millimetres (1⁄32 to 3⁄32 in) in diameter and may be colored from yellowish white to black. They are an important spice in many regional foods and may come from one of three different plants: black mustard (Brassica nigra), brown mustard (B. juncea), or white mustard (Sinapis alba).
Grinding and mixing the seeds with water, vinegar or other liquids creates the yellow condiment known as mustard.
Brassica (/ˈbræsɪkə/) is a genus of plants in the cabbage and mustard family (Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, mustard plants, or simply brassicas. Crops from this genus are sometimes called cole crops—derived from the Latin caulis, denoting the stem or stalk of a plant.
The genus Brassica is known for its important agricultural and horticultural crops and also includes a number of weeds, both of wild taxa and escapees from cultivation. Brassica species and varieties commonly used for food include bok choy, broccoli, Brussels sprouts, cauliflower, cabbage, collard greens, choy sum, kale, kohlrabi, napa cabbage, rutabaga, turnip and some seeds used in the production of canola oil and the condiment mustard. Over 30 wild species and hybrids are in cultivation, plus numerous cultivars and hybrids of cultivated origin. Most are seasonal plants (annuals or biennials), but some are small shrubs. Brassica plants have been the subject of much scientific interest for their agricultural importance. Six particular species (B. carinata, B. juncea, B. oleracea, B. napus, B. nigra, and B. rapa) evolved by the combining of chromosomes from three earlier species, as described by the triangle of U theory.