Kohlrabi and Brussels Sprouts Are European
Certain vegetables of American origin have been called "new" in the sense that they have attained widespread importance in the last two hundred years or thereabouts, although those plants doubtless were used for food in America for hundreds, even thousands, of years before its discovery. Kohlrabi and brussels sprouts, however, apparently were unknown anywhere more than a mere 400 to 500 years ago. They appear to be really new, and the only common vegetables of North European origin.
Although kohlrabi (Brassica oleracea variety caulo-rapa) and brussels sprouts (B. oleracea variety gemmifera) appear radically different from each other, they are merely different horticultural forms or races of the same species, Brassica oleracea, to which common cabbage, kale, broccoli, and cauliflower belong. They all came from a common parent, "wild cabbage".
"Kohlrabi" Means "Cabbage Turnip"
"Kohlrabi" is a German word adopted without change into our language, Kohl meaning cabbage and Rabi meaning turnip. This "cabbage" with a turniplike enlargement of the stem above ground was apparently developed in northern Europe not long before the 16th century. The marrow cabbage from which it probably came is a cold-tender, nonheading plant with a thick succulent stem, while kohlrabi as we know it is a hardy vegetable, evidently developed in a cool climate.
The first description of kohlrabi was by a European botanist in 1554. By the end of the 16th century it was known in Germany, England, Italy, Spain, Tripoli, and the eastern Mediterranean. It is said to have been first grown on a field scale in Ireland in 1734, in England in 1837. In the United States, records of its use go back to 1806.
The plant is easy to grow, is remarkably productive, and an ideal garden vegetable if one does not make the mistake of planting too much of it. Some of my war-gardening friends became literally fed up with it a few years ago when they planted long rows of it in their gardens, all at one planting time, and then at harvest tried to eat it all to keep it from being wasted!
Kohlrabi has never become an important vegetable, but it is one of those things of which most of us would enjoy a limited amount. Some dislike its flavor, which is similar to that of the turnip but milder and sweeter if the vegetable is harvested before it becomes too old and tough.
Two main types are grown in America, white and purple. The "white," actually light green, is much the more popular although the purple variety is most attractive. In Europe, fancy kinds with frilled and deeply cut leaves are sometimes grown for ornament.
Like other members of the species B. oleracea, kohlrabi is a biennial-meaning that it requires parts of two growing seasons, with a cool rest period (wintertime) between, in order to produce seed.
Brussels Sprouts Require Cool Climate
Brussels sprouts are so named partly because the plant is supposed to have been grown since time immemorial in the vicinity of Brussels in Belgium. Though it probably first attained importance in that area, or even was developed there, it has been known for about 400 years. The first rough description of it was in 1587, and some famous botanists as late as the 17th century referred to it only as something they had heard about but had never seen.
The brussels sprouts plant is really a tall stemmed cabbage in which many tiny heads ("sprouts") form along the stem at the bases of the leaves instead of making one large head at the top of a short stem. After a head of common cabbage is cut from the plant, numerous tiny heads often will grow from the remaining stem in much the same manner as in brussels sprouts.
Brussels sprouts need a long, cool growing season, like that of northern Europe and the British Isles. Most of the crop grown in America is produced on Long Island, New York.
Because this plant is so new and so limited in the places where it can be grown easily, its history has hardly begun. By 1800, however, it was commonly grown in Belgium and France, and by 1850 it was becoming popular in England, where it is in high favor today.
Although this vegetable has been known since about 1800 in America, it is far from common here and not highly popular.
Varieties range from short to tall, but are otherwise not strikingly different. The existence of few forms and the lack of many names, or old names, support the belief that the brussels sprouts is a new form botanically as well as agriculturally.
Since this plant is actually a form of cabbage, it will hybridize freely with common cabbage and other forms of the same species: kale, cauliflower, kohlrabi, broccoli, and collards. In the production of seed for planting, cross-pollination with any of these other forms is disastrous, because such seed will produce intermediate mixed offspring.