Wikipedia Article About Black mustard seeds on Wikipedia Black mustard (Brassica nigra) is an annual weedy plant cultivated for its seeds, which are commonly used as a spice. It is commonly used in Indian cuisine, for example in curry. Black mustard is believed to be native to the southern Mediterranean region of Europe, and has been cultivated for thousands of years. It has racemes of yellow flowers. The spice is generally made from ground seeds of the plant, with the seed coats removed. The seeds vary in color from dark brown to black.