vegetable-producing plant, root, tuber or bulb tree onion plant Allium ×proliferum (Moench) Schrad. ex Willd. Tree onions, also commonly called top onions or Egyptian onions, are a strong-growing onion with a bunch of bulblets where a normal onion would have flowers. In some varieties these bulblets will sprout and grow while still on the original stalk, which may bend down under the weight of the new growth, giving rise to the name, walking onion. [Source: Wikipedia] beltsville bunching onion catawissa onion egyptian onion top onion wakegi onion allium species requires discussion