Leek

Leek is a biennial plant that forms thick cylindrical white shafts and flat blue-green leaves in its first year. In the second year it sends up a tall flower stalk topped with a large round umbel of tiny pinkish-white flowers. These produce small, angular, matte black seeds about 2 to 3 millimetres across, wrinkled and shaped like a segment of an orange, with a faint onion smell when crushed. Seeds are sold in packets for gardeners and in bulk for commercial growers, with varieties ranging from fast summer leeks to hardy winter types. Leek seeds are also sold as sprouting seeds, which grow into thin green shoots with a mild onion flavour.

The leek is a cultivated form of Allium ampeloprasum, a wild species native across the Mediterranean and western Asia. It was domesticated in the eastern Mediterranean or Near East, with selection for thick blanched shafts. The scientific name ampeloprasum comes from Greek words meaning vine leek, and porrum is the Latin word for leek. The English word leek comes from Old English leac, a word that also appears in garlic, which originally meant spear leek. The seed shape and color are typical of onion-family plants.

Leeks were grown in ancient Egypt and Mesopotamia, and are mentioned in the Bible among the foods the Israelites missed in the wilderness. Egyptians left leek remains in tombs, and the Greeks and Romans prized the vegetable. The Roman emperor Nero was nicknamed Porrophagus, the leek-eater, because he ate it for his voice, according to Pliny, and Romans carried leeks to Britain.

In the medieval period, leeks were a staple in northern Europe in pottage and soups, and the leek became a national symbol of Wales, where tradition links it to a battle in which soldiers wore leeks to identify each other. Shakespeare refers to this in Henry V.

Selection through the centuries created long-shafted varieties in France, Belgium and the Netherlands, with seed saved by growers who left plants to flower in their second year. Modern seed companies breed hybrids with resistance to rust and bolting. Leek seeds stay viable for only a short time compared with many vegetables, usually two to three years if stored cool and dry, so fresh seed is advised for good germination.

Leek seed is mostly sown to raise leeks, which are used in soups such as vichyssoise and cock-a-leekie, tarts, gratins, braises and stocks. Seeds can also be sprouted or grown as microgreens to add a gentle onion flavour to salads and garnishes. Leeks are started in seed trays in spring and transplanted into deep holes or trenches to blanch the stems. The flowering heads are attractive to bees and are sometimes grown as ornamentals. Dry seed heads are used in dried flower arrangements.

Leek leaves and shafts provide vitamin K, folate, vitamin A and manganese, as well as sulfur compounds and flavonoids such as kaempferol. Allium vegetables as a group have been linked in population studies to lower risk of some digestive cancers, but the evidence for leeks specifically is limited and does not show that they treat or prevent disease. Leek seeds are not a significant food source of nutrients, and sprouts are eaten in small amounts for flavour.