Family Brassicaceae (or Cruciferae), composed of 350 genera of mostly herbaceous plants with peppery-flavored leaves.
The pungent seeds of some species lead the spice trade in volume traded. Mustard flowers take the form of a Greek cross, with four petals, usually white, yellow, or lavender, and an equal number of sepals. The seeds are produced in podlike fruits. Members of the mustard family include many plants of economic importance that have been extensively altered and domesticated by humans. The most important genus is Brassica (see brassica ); turnips , radishes , rutabagas , and many ornamental plants are also members of the family. As a spice, mustard is sold in seed, powder, or paste form.