The leek is a vegetable, a cultivar of Allium ampeloprasum, the broadleaf wild leek. The edible part of the plant is a bundle of leaf sheaths that is sometimes erroneously called a stem or stalk.

Exhibit A: elephant garlic (Allium ampeloprasum var. ampeloprasum). You might be familiar with the giant elephant garlic bulbs you've seen at the grocery store, but the plant's gorgeous flowers ...