Brassica juncea

Brassica juncea, also known as mustard greens, Indian mustard and leaf mustard, is a species of mustard plant.

Food
Cultivars of B. juncea are grown as green vegetables and for the production of oilseed.

B. juncea subsp. tatsai has been selected to grow an especially thick stem, used to make the Chinese pickle zha cai.Other sub-varieties include Southern Giant Curled Mustard which resembles a headless cabbage such as Kale, but with a distinct horseradish-mustard flavor.

The mustard made from it is called brown mustard.

In Africa, the leaves are cooked as a vegetable.

Mustard plants (also known as green mustard cabbage), the leaves of the Indian mustard plant (Brassica juncea), are one of the greens considered to be an essential element in soul food. They are more pungent than the closely-related Brassica oleracea greens (kale, cabbage, collard greens, et cetera) and are very frequently mixed with these milder greens in a dish of "mixed greens", which can also often include wild greens such as dandelion. As with other greens in soul food cooking, they are generally flavored by being cooked for a long period with ham hocks or other smoked pork products. Mustard greens are also extremely high in Vitamin A and Vitamin K.

Chinese and Japanese cuisines make much more use of mustard greens. A large variety of B. juncea cultivars are grown and enjoyed, such as zha cai (tatsoi), mizuna, takana (var. integlofolia), juk gai choy, and hseuh li hung (雪里红). Asian mustard greens are generally stir-fried or pickled. A South-East Asian dish called asam gai choy or kiam chai boey is often made with leftovers from a large meal. It involves stewing mustard greens with tamarind, dried chillies and leftover meat on the bone.

Food supplement
B. juncea can hyperaccumulate cadmium and many other soil trace elements. Specially cultured, it can be used as a selenium, chromium, iron and zinc food supplement.

Green manure
Vegetable growers sometimes grow mustard as a green manure. Its main purpose is to act as a mulch, covering the soil to suppress weeds between crops. If grown as a green manure, the mustard plants are cut down at the base when sufficiently grown, and left to wither on the surface, continuing to act as a mulch until the next crop is due for sowing, when the mustard is dug in. In the UK, summer and autumn-sown mustard is cut down from October. April sowings can be cut down in June, keeping the ground clear for summer-sown crops. One of the disadvantages of mustard as a green manure is its propensity to harbour club root.

Phytoremediation
This plant is used to remove heavy metals from the soil in hazardous waste sites because it has a higher tolerance for these substances and stores the heavy metals in its cells. The plant is then harvested and disposed of properly. This method is easier and less expensive than traditional methods for the removal of heavy metals.It also prevents erosion of soil from these sites preventing further contamination.