Mustard Family (Brassicaceae)
Mustard Family (Brassicaceae)
The mustard family, or Brassicaceae, contains about 3,000 species of plants. These plants occur widely on all continents except Antarctica and in a wide range of habitats from tundra and desert to forests of all types. Most species in the mustard family occur in the temperate zones, and many occur in the alpine or arctic tundra.
The flowers of members of the Brassicaceae have four petals arranged in a cross-like pattern (the old name for this family was Cruciferae, referring to the cross of crucifixion). The flowers of mustards contain both female and male parts (i.e., they are monoecious). There are six stamens, of which four have long filaments, and two have short filaments. The seeds of plants in this family are contained in a relatively long inflated structure called a silique, or in a rounder flattened structure known as a silicle. When mature, the outer walls of the fruits fall away, leaving an inner partition to which the seeds are loosely attached.
A few species of the mustard family are of major economic importance. These include the many varieties of the cabbage as well as rapeseed (or canola), radish, mustard, and others. Other species in this family are used in horticulture, and a few are considered important weeds.
The cabbage occurs in a remarkably wide range of cultivated varieties. Each of these varieties represents culturally selected variants of the basic species, the colewort (Brassica oleracea ), originally native to Eurasia. Hybridization with some other species of Brassica was also likely important in the development of some of the domesticated varieties of the cabbage.
The most common variety in cultivation is the garden cabbage, a biennial plant harvested after the end of its first growing season and eaten as a nutritious vegetable. This variety has been cultivated in the Mediterranean region for thousands of years. The fleshy leaves are aggregated into a head like structure and are eaten raw or processed into cole slaw, sauerkraut, or some other dishes. The most common variety is green colored, but there is also a red variety known as red cabbage. The savoy cabbage is a less-common, more open-headed variety.
The curly kale is a leafy vegetable that does not form a compact head. Brussels sprouts look like tiny cabbages, but they develop in large numbers on the erect stem of this variety of cabbage. These sprouts can be harvested, and new ones will re-grow until the first hard frosts of autumn stop the regeneration. Kohlrabi is a starchy vegetable that develops as a short, inflated part of the above-ground stem. Kohlrabi can be green, white, or red in color. Cauliflower is a compact, white, modified inflorescence. Broccoli is a more erect, green, modified inflorescence.
All of the varieties of cabbage are very nutritious foods, high in energy, vitamin C, iron and other minerals, roughage, and other useful qualities.
There are also some horticultural varieties of cabbage. These are valued for their multi-hued foliage of green, purple, and red. The colors of these plants last well into the early winter, so these horticultural cabbages can brighten gardens long after flowers have withered and the foliage of most ornamental species has been shed.
The turnip (Brassica rapa ) is a biennial, cultivated plant. The starchy, yellowish, inflated root of this plant can be used as food by people, or it may be fed to livestock. The swede (Brassica napus ) produces an edible structure similar to that of the turnip.
Radish (Raphanus sativus ) is a plant that develops an underground, starchy, bulb like structure in the tissue region known as the hypocotyl, occurring between the true roots and the above-ground stem. The familiar radish that is eaten is this inflated hypocotyl. The most commonly grown variety is a round, red radish with a white interior, but white and black varieties of various shapes also occur.
The pungent root of horse radish (Cochlearia armoracia ) is harvested and ground with vinegar to manufacture a delicious, sharp-tasting condiment, often served with meats.
Mustard is a yellow condiment prepared from the ground seeds of white mustard (B. alba ). Sometimes the seeds of black mustard (Brassica nigra ) are also used for this purpose.
The seeds of rapeseed or canola (Brassica napus ) contain up to 40% or more oil, which is extracted under pressure and used as an edible oil and for the preparation of margarine. The material left after the oil has been expressed is used as a nutritious fodder for livestock. Since the mid-1990s, rapeseed varieties have been genetically engineered to be resistant to the herbicide glyphosate, allowing the use of that chemical to combat weeds during cultivation. However, the growing of transgenic crops has become extremely controversial, and many consumers object to the presence of oil from genetically engineered rapeseed in their foodstuffs.
Several other species of mustards are utilized for their edible leaves. The bok choy (Brassica chinensis ), petsai (B. pekinensis ), and false bok choy (B. parachinensis ) are important as cooked or steamed vegetables in the Orient. Watercress (Nasturtium officinale ) is an annual aquatic plant whose tender, dark-green leaves are served as a steamed vegetable. Spinach (Spinacia oleracea ) is another leafy, annual plant in which the raw or steamed foliage is eaten as a nutritious vegetable.
Variety —In systematics, this refers to some identifiable, genetically based group within a species. Varieties do not receive taxonomic rank as subspecies, and they are often bred by humans for use in agriculture. The latter may be called cultivated varieties, or cultivars.
Weed —Any plant that is growing abundantly in a place where humans do not want it to be.
A few species of the mustard family are considered important weeds. Agricultural weeds include various species of mustards in the genus Brassica, some of which are naturalized varieties of cultivated species. A few species are invasive into natural habitats, for example, the marsh cress (Rorippa amphibia ), garlic-mustard (Alliaria petiolata ), and dame’s rocket (Hesperis matronalis ). A few species are minor, aesthetic weeds of lawns and paths, for example, shepherd’s purse (Capsella bursa-pastoris ) and whitlow-grass (Draba verna ).
Judd, Walter S., Christopher Campbell, Elizabeth A. Kellogg, Michael J. Donoghue, and Peter Stevens. Plant Systematics: A Phylogenetic Approach. 2nd ed. with CD-ROM. Suderland, MD: Sinauer, 2002.