Mustard is a well-known oil seed and an annual crop. It has round stem with long inter-modes, simple, alternate and very soft yellowish green leaves. The fruit is a pod containing seeds. Dry mustard seeds are small, round and darkish-brown or grayish-brown in color. They have no smell, but when pounded and moistured with water, they emit a peculiar strong smell.
Mustard oil is of vegetable origin and is obtained from seeds of the black and white (Sinapis alba) mustard plants. In the crude state, black mustard oil (Brassica nigra, light color) has a spicy odor and a strong taste. When refined it is neutral in odor and taste. White mustard oil (yellow color) has a bitingly pungent taste due to the allyl mustard oil it contains.