cepa

Cepa is best known in biology as the species epithet of the common onion, Allium cepa. The Latin cepa means onion, and the plant belongs to the genus Allium in the Amaryllidaceae family. Allium cepa is typically grown as an annual for its edible bulb and is widely cultivated around the world.

Allium cepa is a bulbous, herbaceous plant. The bulb consists of concentric fleshy scales, usually covered by a papery tunic. From the bulb arise hollow leaves and a flowering stalk that bears an umbel of small flowers, commonly white to purple depending on the cultivar. Although a biennial by nature, it is grown and harvested as an annual in agriculture and home gardens.

Cultivation varies by climate. There are short-day and long-day varieties suited to different latitudes. Successful growth requires well-drained soil, regular moisture, and adequate daylight. After harvest, onions store well and are a staple ingredient in many cuisines. Global production includes both bulb onions and greens commonly referred to as scallions or spring onions.

Uses and varieties. The bulb is the primary edible portion and is used in countless culinary traditions for flavor and texture. Green onions, harvested immature, are also widely consumed. Onions contain sulfur-containing compounds that contribute to aroma and flavor, and they provide nutrients such as vitamin C, dietary fiber, and potassium.

Etymology. The epithet cepa derives from Latin for onion, a reflection of the plant’s long history in cultivation. The name Allium cepa distinguishes the common onion from related Allium species.