Brassica juncea that has been grown in high levels of selenium. Brassica juncea is a plant of the cabbage family that has been used in some cultures to treat certain medical problems, including arthritis, colds, stomach disorders, and tumors. The plant stores minerals, including selenium which may stop tumor cells from growing. High-selenium Brassica juncea is being studied in the treatment of cancer. Brassica juncea is also known as Indian mustard.