The bulbous onion and its numerous relatives belong to the Lily family. Some of these alliums are distinctly ornamental; a few others, notably garlic, leek, Welsh onion, and chive, are common vegetables. All of the edible forms have related flavors and odors that are due principally to a volatile, irritating substance.
Our word "onion" comes from the Middle English union, from the French oignon, which came in turn from the Latin unio, meaning "onion." Ancient names for this plant in Sanskrit, Hebrew, Greek, and Latin are apparently unrelated, indicating a widespread culture of onions from prehistoric times.
The common onion (Allium cepa), leek, and garlic originated in middle Asia, with secondary centers of development and distribution in western Asia and the Mediterranean lands. The Welsh onion is believed to be of Chinese origin. The word "Welsh" here is a translation of the German 'walsch', both meaning "foreign," and does not refer specifically to Wales but to the distant origins of the plant.
Onions were used extensively by the ancient Egyptians, as shown by drawings and inscriptions on their monuments. The Bible states how, during the wanderings of the Israelites in the wilderness, they longed for the onions, leeks, and garlic they had had in Egypt.
In the first century, many varieties of onion were known: long, round, red, yellow, white, strong, and mild kinds. For a time in the Middle Ages, it appears that the onion was less popular than leek and garlic, while now the reverse is true.
The onion was introduced by the Spanish into the West Indies soon after their discovery. From there it soon spread to all parts of the Americas. Onions were grown by the earliest colonists and soon afterward by the Indians.
The Welsh onion (A. fistulosum) never forms a rounded bulb-only one to several long white scallions. This form is most popular in the Orient but is grown almost everywhere. In Japan, it is often incorrectly called "Japanese leek."
One form of onion, the so-called Egyptian tree onion, or top onion, produces "sets" (tiny bulbs) at the top of the stalk instead of flowers and seeds.
The leek (A. porrum), like the Welsh onion, forms only a cylindrical instead of a rounded bulb. The leaf of the leek, however, is flattened and solid, while the leaf of the onion is cylindrical and hollow.
Our word "leek" comes from the Anglo-Saxon leac. The Romans called it porrum, that term is retained in its present Latin name. It has been used for food since prehistoric times.
In the first century, the Romans considered that the best leeks came from Egypt, where they had been known in the earliest Biblical times. Emperor Nero is reported to have been nicknamed Porrophagus because of his inordinate appetite for leeks. He imagined that frequent eating of leeks improved his voice!