Large genus of onion- or garlic-scented bulbous herbs of the amaryllis family (Amaryllidaceae). Allium species are found in most regions of the world except the tropics and New Zealand and Australia. Several are important food crops, including the onion (Allium cepa), garlic (A. sativum), chive (A. schoenoprasum), and leek (A. porrum), and some are cultivated as ornamental border plants.