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Alliaceae

The Alliaceae or onion family was once included in the monocot family Liliaceae, but is now recognized by many as a separate plant family. The family includes herbaceous (nonwoody) monocot plants that are generally perennial but not evergreen. Most are native to dry or moderately moist regions and other open areas. The family includes bulb or corm-forming plants as well as plants without bulbs or corms. Leaves may be round, flat, or angular in cross section and are alternately or spirally arranged. The leaves of most species in the Alliaceae are aromatic, frequently smelling like onion. Flowers are generally organized into ball-or umbrella-shaped clusters called umbels.

Alliaceae includes several genera. Most genera are not commonly grown, although some species, including examples from Tulbaghia, Nothoscordum, and Ipheion, are occasionally grown as ornamentals. The only widely grown genus in the family is Allium, with approximately five hundred species that are native throughout the Northern Hemisphere. Important Allium species used for food include onion and shallot (A. cepa), garlic (A. sativum), leek and elephant garlic (A. ampeloprasum), Japanese bunching onion (A. fistulosum), chives (A. schoenoprasum), and garlic chives (A. tuberosum).

Many Allium species are also grown as ornamentals including A. giganteum, A. christophii, A. karataviense, A. aflatunense, A. caeruleum, the nodding onion (A. cernuum), the yellow-flowered A. moly, and the interspecific cultivar Globemaster. A few Allium species are also noxious weeds in some parts of the world (e.g., A. vineale and A. triquetrum). The consumption of garlic has been shown to significantly reduce both blood levels of cholesterol and the chance of coronary heart disease. Evidence also suggests that garlic has anticancer and antibiotic properties and can reduce hypertension and blood clotting. Other alliums, particularly onion, have some of the same health benefits of garlic, but effects vary widely between species.