The pearl onion (Allium ampeloprasum var. sectivum or A. ampeloprasum 'Pearl-Onion Group'),^[1] also known as button onion, baby onion or silverskin onion in the UK,^[2] is a close relative of the leek (A. ampeloprasum var. porrum), and may be distinguished from common onions by having only a single storage leaf,^[3] similar to cloves of garlic. In French they are known as oignon grelot. One English-speaking reference also mentions the term petit poireau antillais.^[4]

Pearl onions are cultivated mostly in Germany, the Netherlands, and Italy,^[5] usually in home gardens,^[1] although formerly on a commercial scale.^[4] They are mostly used for pickling.^[6]

Because of its uniquely small size and a taste sweeter than that of a common onion,^[2][7] it has also been used in dishes ranging from mid-20th-century American casserole dishes such as succotash to sweetly flavored onion relishes in Indian cuisine. It can also be used in stews soups or sautéed (fried) with other vegetables.^[8][2][9] It can also be used in cocktails such as "martini standing".^[5]

Pearl onions are a staple to the cuisine of Northern Europe.^{[citation needed]} Also in modern Europe they are used as a flowering plant, and in Israel as a cut flower.^[4]

Pearl onions contain chemical compounds that have health benefits including helping cardiovascular health and stabilize blood sugar levels, and acting as an antioxidant and anti-inflammatory.^{[10][11][better source needed]}

The majority of onions grown for pickling are common onions (A. cepa),^[12] which are normally much larger, but are grown to a small size suitable for pickling by planting them so densely that each one has very little room to grow.^[13]

White varieties of common onions grown in this way for pickling include Crystal Wax^[5] and White Bermuda.^[7] There are red varieties as well, which are milder in flavour.^[10] Common onions grown from seed to produce small bulbs for pickling are ready to harvest in 90 days.^[7] They can be stored for up to a month in a cool, dry, dark place.^[10][11]

Larry Wall's yearly State of the Onion speeches about advancements in Perl programming, an allusion to the many layers of the language, are named as a pun both on the pearl onion and the U.S. president's State of the Union addresses.^{[citation needed]}