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. While these onions are often listed as Allium cepa var. prolifera, recent research has shown that the tree onion is a cross between Allium cepa, the cultivated onion, and Allium fistulosum, the welsh onion. This phenomenon of forming bulblets instead of flowers is also seen in garlic and various wild species of Allium.