Brown mustard

Brown mustard (Brassica juncea), also called Chinese or Indian mustard, is an annual herb of the mustard family (Brassicaceae), 30–100 cm tall, up to 1.5 m in flower, with a rosette of leaves at the base. Basal leaves are large and stalked with wavy or serrate margins and the characteristic pungency from glucosinolates (yielding allyl isothiocyanate). Flowers are bright yellow with four petals in terminal racemes. The fruit is a silique with many small round seeds, brown to black and rich in oil. The species originated in Central Asia, the Himalaya and western China, was domesticated long ago and is grown worldwide in many forms differing in leaf and root type.

Brown mustard is a familiar vegetable in Vietnamese meals: young leaves are eaten raw, cooked in soups, stir-fried or pickled into dưa cải; the seeds are ground into mustard paste and pressed for edible or industrial oil, and the leftover cake is used as livestock feed. Nutritionally, the greens are rich in vitamins A, C and K, calcium, iron and fibre and contain antioxidant glucosinolates; in folk medicine brown mustard is used to clear heat, as a diuretic, an expectorant and a laxative. With a short growing period it is also grown as a cover crop, for soil improvement and green manure. In Vietnam it is grown mainly in the winter–spring crop, common in the north and around Da Lat.