Brown mustards
Brown mustard (Brassica juncea), also known as raya, Indian mustard, and Chinese mustard, is a natural cross between the turnip (Brassica rapa) and black mustard (Rhamphospermum nigra). One of the earliest domesticated plants, the species is thought to have originated in West Asia at least 8,000 years ago.
Root mustard was the first to be selected from wild mustard, about 2,000 to 5,000 years in Mongolia and northeastern China. It is not clear how the plant arrived in that part of Asia.
Seed mustard was selected separately in West Asia, from where it was brought west to Europe and east to Asia. In Asia, this form of B. juncea appears to have taken two separate routes, one through Tibet into northern China, and another through India into southern China.
As it spread along the southern route, B. juncea was selected into an oilseed type called raya, or Indian mustard, in India. In eastern India, it was developed into broad-leaved mustards, eventually reaching southwestern China, where these were grown as leafy vegetables and for oilseed in the 6th century CE. In southern China, these were diversified into further leafy varieties, and into stem mustard in Sichuan in the 1700s. China is currently home to the greatest diversity of brown mustard varieties.
In northern China, a yellow-seeded variety was selected about 500 years ago in Xinjiang, used in the condiment called “Chinese hot mustard”.
I haven’t been able to find when B. juncea reached Europe because all mentions of the seed refer to mustard in general terms, not to the brown mustard species specifically. Either way, cultivation of some kind of mustard dates back to at least the 5th century BCE in Greece and later in Rome. The Romans were big fans of mustard seed as a cooking ingredient and condiment, and that tradition persists in Europe to this day, especially in France and Germany. The French Dijon mustard is especially famous, and is made, according to French law, with brown mustard seed, black mustard seed (Rhamphospermum nigra), or a mix of the two. Contrary to the claims made on some websites, it is not made with white mustard seed (Sinapsis alba).
In the US, we also tend to know Brassica juncea best as a prepared condiment. The “spicy brown mustard” style is derived from a German mustard from the city of Düsseldorf and was introduced by German immigrants. Brown mustard also has a tradition of use in the South as a leafy green, commonly referred to as “mustard greens”. Genetic testing has shown that these leafy varieties have their origins in eastern Asia. Interestingly, I can’t find any reference to mustard greens in Southern American cooking before the 1900s. It appears that unlike collard greens, which have a clear, longstanding history of use, mustard greens are a more recent introduction.
Names for brown mustard
The various names of brown mustard reflect the mixed origins of its different varieties. These names are used very inconsistently in English, likely due to the fact that the plant doesn’t have the same history in European cultures that it does in Asia. There is often either no name for a specific variety in English, or only a generic name. Broad terms like “Indian mustard” or “Chinese mustard” are often applied to varieties from very different provenances. In this article, I’ve tried to select names that help distinguish between the many brown mustard varieties in existence today.
In the Pacific Northwest
Brassica juncea is naturalized throughout the Pacific Northwest (and North America). A fast-growing annual, it excels in cold weather. Like the related colewort, brown mustard can be planted either in spring, for an early summer harvest, or in late summer, for a fall or winter harvest. However, given its origins in West Asia, it’s also more heat-tolerant overall, and with consistent watering, many varieties can be grown through summer in our cooler regions, such as the Northwest Coast.
Species and varieties
Brown mustards
Brown mustard (Brassica juncea)
Leaf selections
Indian mustard greens
Gai choy
‘Dai gai choy’
Snow mustard greens
Mustard greens
Stem selections
‘Zha cai’
Root selections
‘Da tou cai’
Seed selections
Oilseed and raya
Leaf selections
The leaves of any brown mustard plant can be eaten, but many varieties were developed in eastern India and southern China specifically as leafy vegetables.
Indian mustard greens are the broad-leaf mustards that were developed as brown mustard spread eastward into southern China. Broad-leaf mustard varieties are known as “lai patta” in Assamese (spoken in northeastern India). These look very similar to the small “gai choy” varieties eaten in southern China (see below).
Gai choys are varieties Brassica juncea that were developed in southern China. Also referred to as “Chinese mustard”, they have large leaves and stems. Smaller varieties (“sui gai choy”) have thinner stems and leaves. They resemble Indian mustard greens.
Gai choys are adapted to winter cultivation in warm, subtropical climates and do well in cool, but not cold weather. They are less cold-hardy and can’t handle freezing temperatures well, so are best suited to spring and fall cultivation in our region.
The name “dai gai choy” is Cantonese for “big mustard vegetable”. It is also referred to as “Swatow mustard”, in reference the city Shantou in southern China, and “large-petiole mustard” (a pretty clunky name). Dai gai choy varieties have larger stems that form a cabbage-like head. These varieties are especially good for pickling. Cultivation requirements for dai gai choys are similar to regular gai choys.
Snow mustards, or lobed-leaf mustards, known in Chinese as “xue li hong” were developed through the hybridization of northern and southern Chinese varieties of brown mustard. These varieties have large masses of thinner, serrated leaves. They’re also sometimes referred to as “potherb mustard”, or “snow mustard”. The Japanese green mizuna, a type of turnip green (Brassica rapa) is often incorrectly lumped in with this type of brown mustard. Snow mustards are much cold-hardier than gai choys.
As the broad-leaf mustard greens of southern China we brought to Japan and Korea, further varieties with different traits were selected ; these can have red, green, serrated, frilly, curly, or smooth leaves.
The mustard greens commonly sold in the United States generally originate from Asian varieties. American mustard greens are generally from more northern provenances than gai choys and are often able to handle significantly colder weather, easily overwintering in the Northwest Coast region.
Many mustard green varieties are popularly grown as baby greens.
Stem selections
Stem mustard varieties originate in Sichuan, China. The vegetable is called “zha cai” in Mandarin Chinese. The older Cantonese version of the name in English is “jar choy”. Stem mustard was bred from Chinese broad-leaf mustard by selecting for a swollen stem. The vegetable is commonly pickled and is used in many regional Chinese cuisines.
Zha cai can be expected to grow similarly to other southern Chinese brown mustards, such as gai choy.
Root selections
Root varieties of Brassica juncea originate in northeastern China. They are known as “da tou cai” in Mandarin, and often mislabeled “turnip” or “kohlrabi” in English. The literal translation is “big head vegetable”. It’s usually found as a pickled vegetable and almost never seen fresh in the United States, where the vegetable is highly uncommon. As a result, information is fairly limited. Considering its northern origins, however, it should reasonably do well in the Pacific Northwest.
Seed selections
In India and Eastern Europe, brown mustard oilseed is a major crop, but the varieties used are distinct from each other, with those in Eastern Europe derived from the yellow-seeded types that developed much later northwestern China.
In the Pacific Northwest, acreage of brown mustard planted in the Columbia Basin increased significantly as interest in oilseed production grew in the mid-2000s, but it remains a minor crop.
Cooking with brown mustard seed
Oilseed varieties of brown mustard are known as raya or rai in India, where they are used to make cooking oil. Mustard oil is a commonly used staple across northern India, prized for its pungent flavor. Mustard oil is banned for food use by the FDA due to its high erucic acid content. It can still be purchased but is labeled “For external use only”. See the note on erucic acid in the rutabaga article for more information.
Brown mustard seeds are also used as a spice. The seeds are toasted, which destroys the heat of the spice, but brings out a nutty flavor instead.
