According to the Encyclopedia Britannica, kohlarbi is a cabbage of recent European origin. I do not know what the Britannica considers "recent" in the domain of vegetables, but Charlemagne ordered that kohlrabi be grown 12 centuries ago. I suspect that the ancient Romans knew it, although their names for the various members of the cabbage family have never been satisfactorily translated.
One reason for suspecting its early presence in Italy is that it is still eaten there, although it is a heavier vegetable than Italians usually favor. Thus its presence could be accounted for by the well-known obstinacy with which eating habits persist through the centuries. It is, of course, possible that Austrian influence accounts for the popularity of kohlrabi in Veneto, once Austrian territory. It is the sort of bulky, filling food which appeals to peoples living in a continental climate who are relatively insensitive to coarse or insipid flavor. This is certainly not true of Italians. But a counterargument may be found on the fact that our word comes from Italian, caroli rape . This passed into German as Kohlrabi, and entered English in the same form only in the 19th century, which is perhaps why the Britannica decided that it was recent.
One of the difficulties in tracing the history of kohlrabi is that few people seem to know what it is. This refers to popular usage, of course. Botanists have it firmly pinned down as one of the kinds of cabbage, all of which belong to the same species, Brassica oleracea . Fully described: kohlrabi is Brassica oleracea, variety gongledes, subvariety caulorapa, as heavy a mouthful as the food itself.
It is often taken from a turnip because of its appearance but it is definitely a cabbage. The stem swells into turnip shape just above the ground (not under it, like the turnip, which is a root). In Germany, where it is also confused with a root vegetable, a distinction is made by calling the cabbage plant Kohlrabi under de Erde, above-ground kohlrabi, and calling the turnip-like Swede kohlrabi under der Erde , underground kohlarbi.
The scant acquaintance Americans and Britons have with this vegetable no doubt accounts for the misinformation regularly printed about it. Some writers describe it as a hybrid between the cabbage and the turnip which would be impossible, since they do not belong to the same species or even the same genera (they do belong to the same family, Brassica)
Others describe it flatly as a turnip which is, of course, a complete error. They may have been led astray by the name sometimes given it - turnip cabbage. But this is meant only as a description of the edible bulb which swells from its stem.
In an attempt to carry the search for the origin or kohlrabi back even beyond the development of the cabbage, Kurt Opitz of Hamburg wrote me three years ago.
"I have not been able to find hard information on the origins of the (unheaded) cabbage (a category which would include kohlrabi, and its predominantly cabbage-like character is confirmed in the southern United States where the bulb is sometimes neglected in favor of eating the leaves and in mixed greens). Yet it is frequently assumed informally in German sources that all varieties ultimately derive from a plant called Melde in German, of which orache seems to be a cultivated variety. The botanical trouble here is that orache and Melde (for which I have only discovered the obscure English name Good King Henry, a translation of French Bon Henri - and English source calls it a translation of the German Heinrich) are assumed to be related to the spinach, both being chenopodiaceae (orache is also called mountain spinach).
"Spinach, however, is similar to the cabbage in being and oleracea, while orache and Melde are called atriplex. Personally, I can see little relationship between the two, judging from their taste. Melde in fact tastes not at all like spinach (it does not seem to contain any oxalic acid, while spinach contains a lot), but rather like kohlarbi, Melde is a wild-growing herb found all over Central and Northern Europe. In my opinion, however, it surpasses any of the cultivated cabbages in mildness provided the stems are removed before cooking; the blossoms can stay on, and are highly desirable, like broccoli - tenderness."
Some persons, curiously, maintain that kohlarbi tastes like turnip. I think they are misled by verbal association, knowing some of the names which refer kohlrabi to turnip. It certainly does not have the pepery bite of the turnip (most perceptible when it is eaten raw, cooling tames it), but is blander and sweeter.
"Kohlrabi is a most underrated vegetable that more people should grow and eat." Richard Gehman wrote in "The Haphazard Gourment."
The fact that he wrote "should grow" underlines one fact: It is not often found on the market nowadays, so if you want taste it you will usually have to grow it yourself.