Is the onion genus, with 600-750 species, making it one of the largest plant genera in the world.

They are perennial bulbous plants that produce chemical compounds (mostly cysteine sulfoxide) that give them a characteristic onion or garlic taste and odor, and many are used as food plants, though not all members of the family are equally flavorful.

Allium species occur in temperate climates of the northern hemisphere, except for a few species occurring in Chile (such as Allium juncifolium), Brazil (Allium sellovianum) or tropical Africa (Allium spathaceum). They can vary in height between 5 cm and 150 cm. The flowers form an umbel at the top of a leafless stalk. The bulbs vary in size between species, from very small (around 2–3 mm in diameter) to rather large (8–10 cm). Some species (such as Welsh onion, A. fistulosum) develop thickened leaf-bases rather than forming bulbs as such.

from: Wikipedia