Allium

Allium is the genus of onions with about 1250 species of perennial bulbous plants. The onion is probably native to southwestern Asia but is now grown throughout the world, chiefly in the temperate regions. There are several species of Allium or onion that are grown exclusively for their flowers instead of their bulbous structures. Ornamental onions are not planted in the vegetable garden, but in beds or borders with other perennial flowers. Flower heads on ornamental onions are usually globe shaped and appear in late spring to mid summer.

Kingdom

Plantae

Division

Magnoliophyta

Class

Liliopsida

Order

Asparagales

Family

Alliaceae

Genus

Allium

Allium plants vary in height between 5 cm and 150 cm. The flowers of allium form an umbel at the top of a leafless stalk. Alliums have strappy, undistinguished leaves and straight tubular flower stalks. The flower form in clusters and are best known in the round pom-pom form, but they can be start shaped, cup-shaped, semi-circular or pendulous.
The Allium bulbs vary in size between species, from very small to rather big. Some species (such as chives, Allium schoenoprasum) develop thickened leaf-bases rather than forming bulbs. Most bulbous alliums increase by forming little bulbs or offsets around the old one, as well as by seed. Several species can form many bulbils (tiny bulbs) in the flowerhead; in the so-called tree onion (Allium cepa Proliferum Group) the bulbils are few, but large enough to be used for pickling.

Facts About Alliums

• Onions were used extensively by the ancient Egyptians, as shown by drawings and inscriptions on their monuments.
• The wide use of alliums as ornamental plants is a more recent phenomenon, first gaining favor about the middle of the 19th century.
• Onions are among the world's oldest cultivated plants. They were probably known in India, China, and the Middle East before recorded history. Ancient Egyptians regarded the spherical bulb as a symbol of the universe.