The leek is a vegetable, a cultivar of Allium ampeloprasum, the broadleaf wild leek. The eatable part of the forest is a bundle of leaf sheaths that is sometimes erroneously called a stem or stalk. The genus Allium then contains the onion, garlic, shallot, scallion, chive, and Chinese onion.
Historically, many scientific names were used for leeks, but they are now everything treated as cultivars of A. ampeloprasum. The name ‘leek’ developed from the Old English word leac, from which the advanced English read out of garlic in addition to derives. Three next door to related vegetables, elephant garlic, kurrat and Persian leek or tareh, are with cultivars of A. ampeloprasum, although alternative in their uses as food.