(Brassica juncea ssp. integrifolia – Family Cruciferae [Brassicaceae])
Mustard greens, leaf mustard, Indian mustard, Chinese mustard cabbage, gai choy, swatow mustard
Mustard greens are members of the cabbage family (Cruciferous) and relatives of Sarepta mustard (ssp. juncea).
Technically, the term “mustard greens” refers to a single species of Old World plants (Brassica juncea), which is thought to have originated in the Central Asian Himalayas before spreading to China, India, and the Caucasus.
However, taxonomists identify as many as seventeen subgroups that can differ sharply in heat, flavour, and appearance. The colours can range from lime green to burgundy, from smooth to prickly, nippy to fiery, chewy to fibrous and when harvested young, may not even resemble the plant at the older stage.
Two wild European mustards, ancestors of the cultivated species, are the field mustard (ssp. campestris)
and charlock (Sinapis arvensis). Charlock is also known as corn mustard,and often eaten in Ireland, the Hebrides, and Sweden.
Field mustard has cultivated species called Indian colza
and Indian rape. In its wild form, it is known as kalewort or summer rape in England. The name colza comes from the Dutch kool zad, which means kale seed.
Mustard leaves can vary greatly in shape from curly to forming firm heads with thickened leaf stalks. They should always be briefly blanched or boiled because of their bitter pungent taste.
In China, mustard cabbage
is preserved like sauerkraut and pickled in lactic acid. The lactic acid takes the edge off the bitter substances contained in the greens, while simultaneously adding a spicy taste.
The popular and convenient mix of salad greens usually contains two baby mustard greens, tatsoi
Tatsoi is an ornamental mustard with dark green (almost black) spoon-shaped leaves with white stems. It is sometimes called flat Chinese cabbage.
Mizuna has a light green, very deeply notched leaf that has a feather look. It is milder than most mustards and reminiscent of arugula, but sweeter.
In the southern US, the liquid is saved from the cooking of the greens and used for dunking cornbread or, like all vegetable liquid should be, reserved for soups or stews. The water can also be used as part of the liquid in muffins, pancakes, breads, etc.
Mustard greens are an excellent source of vitamins C and E, fiber, folate, calcium, iron, magnesium, potassium, and B6. The calcium in mustard greens ranks high in its bioavailability. It is best to choose mustard greens that are young and tender, no longer than eight inches, and use them as quickly as possible.
All young mustard greens deteriorate faster than the mature leaves. They can be wrapped in paper towels and put in a plastic bag and stored in the refrigerator for a short period of time.
Mustard greens can be steamed, boiled, sautéed, or braised for ten to twenty minutes. The longer they are cooked, the softer the flavour becomes. If cooked just until just tender, they will have a spicy flavour.
Baby mustard greens, on the other hand, can be eaten raw in salads or sandwiches.
Southern mustard, American mustard, curled mustard, Southern curled mustard
(Brassica juncea ssp. crispifolia)
Southern mustard is a curled leaf plant that is the most commonly sold variety in the US. It is sold as mature greens and looks like a delicate version of kale, having jade green leaves that are crinkled or ruffled, but more tender than kale. However, it can deliver a hot, mustardy punch.
Other varieties include the following:
Wrapped Heart mustard, dai gai choy (and other Chinese variations), Swatow mustard, Swatow cabbage, heading mustard
It appears most often in Asian and Oriental markets and comes in various forms of ribbed, romaine-like leaves that swirl into flattened heads and looks like a light green cabbage head wrapped up in a dark green baseball glove. Raw, it has a ferocious bite that is traditionally tamed by salt-pickling (kimchee). It is used primarily in Chinese soups or is pickled to make “haam suen choy”, which resembles sauerkraut. Cooked, its fleshy stalks and leaves turn a bright jade green, which are bittersweet, but juicy.
Bamboo, leaf mustard, small gai choy, stickleaf mustard, juk gai choy (and other Chinese variations)
This is a light or darker romaine-green variety that has other variatiions: multi-branched or single-stemmed, wide or slim stemmed, ribbed or not, leafy or not as much. It is always smaller (juk means small) than dai gai choy (dai means large). It looks quite similar to Chinese broccoli raab, but without the flowers. The stems are generally narrow, rounded, or celery-shaped, and almost as juicy and mild as bok choy. The slightly ruffled, fairly narrow leaves are thin and lettuce-like, but still maintains a sweet, but mild mustard nip. As with all mustards, taste before it is used as some will be decidedly stronger than others.
Red-in-Snow mustard, green-in-snow mustard, hseuh li hung (and other Chinese variations)
This has green, loosely-bunched, sharply serrated leaves which resemble (but are not) a mizuna-dandelion cross. Since it is a green mustard, one wonders where the ‘red’ fits in. One explanation is the since the Chinese love red, that colour is inserted into anything they love, including green mustard vegetables. Like wrapped mustards, this one is traditionally blanched, then fermented with salt and vinegar for a popular sour pickle used in soups and stir fries. Raw, however, offers a unique blend of very sweet, herbal, and cabbagey flavours with a touch of spiciness.
Giant-leafed mustard, Japanese mustard, purple mustard, red mustard, aka takana (Japanese)
This has leaves that are a fine blend of green and purple in their leaves, as well as some having each of the colours in full. The colours develop in the colder climates, where the red or purple tones deepen and fade in warmer zones or in greenhouses. Although Chinese in origin, these mustards have been adopted by Japan as some of their names indicate: Osaka Purple, Miike Giant, Aka Takana, Aka Chirimen. Although the leaves can grow to be quite large, the tenderness is not affected; but their hot flavour definitely increases with age. Aka takana is especially known on the southern island of Kyushu, where other plants do not grow in the volcanic ash. There, as in China, it is used primarily for pickles which are very popular all over Japan in soups and sometimes wrapped around rice instead of seaweed.
Garlic mustard, hedge garlic, jack-by-the-hedge, sauce-alone (Alliaria petiola and A. officinalis)
This is rare to find in a market, but grows abundantly in the wild. It has the popular perfume of garlic and the kick of a mustard, and so is popular with chefs looking for a new green to spring on their customers. Like Brassica juncea, garlic mustard is a member of the huge Cruciferae family, although through a different genus. Despite this, it allies itself more closely with mustard greens than with any other group. In the early spring, the serrated, heart-shaped leaves are a bright green and found growing in open woodlands from spring to fall. Late in the season, however, the plant can become inedibly bitter, turning mellow and edible again during the winter.