in botany, a genus of the tetradynamia filiquosa clas. The calyx is open; the petals have straight unguis; and there is a nectarious gland between the short lamina and the pistillum, and between the long stamens and the calyx. There are ten species, three of them natives of Britain, viz. the nigra, or common mustard; the alba, or white mustard; and the arvensis, or wild mustard.

Mustard-seed is an attenuant and resolvent in a very high degree; it warms the stomach, and excites an appetite; but its principal medicinal use is external in sinapisms, applications made to certain parts when irritation is intended, but not blistering. It is usually mixed with horse-radish root, and other ingredients of the same kind, for this purpose.