Allium cepa
Bulbiferous herb with scales, dividing bulbs of up to 10 cm in diameter, tunicated. Basal leaves, up to 40 cm, hollow, semicircular in cross section. Scape of up to 60 cm in height. Abundant purple or almost white flowers, grouped in a large spherical umbel, with 2 to 3 bracts. Capsular fruit. Rarely produces seeds.