Brassica juncea is a member of the mustard family of plants, also called Brassicaceae. The plant has many names, including Indian mustard and Chinese mustard, depending on where it is consumed. One of many mustard family plants used as food, it can also be grown industrially to extract heavy metals from contaminated land areas.
Indian mustard grows to an average height of 3 feet (1 meter) or more. It is an annual plant, dying after its one year life cycle, and can be grown in the winter or summer. The leaves reach a length of 12 inches (30 centimeters) and a width of 4 inches (10.16 cm) or more. Flowers usually appear at the top of the stem. These half inch (1.27 cm) flowers are always yellow and have four petals with four sepals in between.
Mustard greens are known and used, mostly as food, in various countries. Every part of the plant is edible except for the root. Young leaves are a common feature in salads. They have a potent taste and are often mixed with milder vegetables like cabbage and kale. As the mustard matures, the leaves can be eaten right off the plant or even stored for later use by canning or freezing.
Consumed internationally, mustard greens are incorporated into Italian and African cuisine, while Indian food features them extensively. Chinese and Japanese cooking also frequently employ Brassica juncea in their dishes. In Italy and Africa the leaves are favored, while most Asian cuisines make use of the entire plant, excluding the root. A dish called Zha cai is prepared in China, in which the knob-like portion of the mustard stem is pickled and fermented in a manner similar to Korean kimchi dishes. The mustard greens are also stir fried and paired with chillies.
Sarson da saag, a famous Indian curry dish, made in the mountainous regions near Nepal, is based heavily on mustard greens. Indian cuisine uses all edible parts of the plant, which can be served individually or incorporated into a recipe with various ingredients. The Indian mustard is pickled in India as well, where it is mixed with numerous spices and local ingredients. Mustard oil can be extracted from the seeds of the Brassica juncea. Mustard greens are also made into food supplements because of their ability to rapidly accumulate minerals like iron and zinc.
Brassica juncea is an important plant for phytoremediation. This process uses organisms like plants to treat or extract harmful chemicals from hazardous waste sites. Indian mustard, which has a high tolerance for heavy metals, is particularly adept at phytoremediation. The mustard is planted at the contaminated site, where it absorbs most heavy metals, particularly lead, and traps them in its cells. When the plants begin to die, they are removed and disposed of, allowing a new batch to be planted.