Wikipedia Article About Welsh Onion on Wikipedia Welsh onions are Allium fistulosum (Alliaceae). They are also known as green onions, bunching onions and scallions, but those terms refer more to function than taxonomy and can include some types of garden onion (Allium cepa) or shallots. Welsh onions never form a solid bulb, and the scape, like the leaves, is hollow and fragile. In addition to their use in cooking, they are often grown in a bunch as a foliage ornamental perennial.