Scallions generally have a milder taste than most onions and their close relatives include garlic, shallot, leek, chive, and Chinese onions. The onion, also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus Allium. The shallot is a botanical variety of the onion which was classified as a separate species until 2010. Its close relatives include garlic, scallion, leek, and chive. Spring onions, on the other hand, are a different thing. The bulb of a spring onion is much larger, compared to the small, not-so-bulbous scallion. The bulb of a spring onion actually looks like a mini onion, spherical and bright white. Green onions and scallions are actually the same thing! They are either harvested very young from the regular bulb-forming onions we are familiar with, or they can come from other varieties that actually never form bulbs. Scallions are long, with a white stem end that does not bulge out. They are called scales – outer ones are membranous and inner ones fleshy. The protective thin outer covering is called tunic. An onion is neither a root nor a stem. It is a tunicate bulb having a cluster of fleshy leaves. An onion is a modified underground stem structure. The onion plant stores its processed food in the bulged leaf structure at the base. Onions consist mostly of water, carbs, and fiber. Their main fibers, fructans, can feed the friendly bacteria in your gut, though they may cause digestive problems in some people. Abstract. Allium cepa, commonly known as onion, is a worldwide culinary and therapeutic spice belonging to the family Liliaceae. Onion is an essential ingredient in many African sauces and is mostly produced locally, with Egypt being the first producer in the continent.