Onions come in a variety of sizes, from the size of large marbles to softballs. Onion varieties include full-flavored and versatile yellow onions; cipollini; white onions, which have a higher water content and are slightly sweeter; Spanish onions, which are very large yellow onions; and red onions, also called Bermuda onions, which are sweeter and milder. Sweet onions, such as Vidalia, Maui, and Walla Walla onions, named after the locations in which they’re grown, are usually available only during spring and summer. Green onions are small, with their tender greens still attached, and have a fresh, bright flavor. Scallions are long and slender, with white roots fading into green tops, and a delicate flavor. Leeks look like larger scallions and have an earthier flavor. Ramps look like tiny leeks, but the greens are delicate and can be used with the white bulbs, and the flavor is more assertive and wild. Shallots are sold as firm, violet-tinged bulbs in golden skins; they have a more intense flavor, without the harshness of onions or garlic.