Giant onion

Description

Allium giganteum, common name giant onion, is an Asian species of onion, native to central and southwestern Asia but cultivated in many countries as a flowering garden plant. It is the tallest species of Allium in common cultivation, growing to 1.5 metres (4.9 ft). In early to midsummer, small globes of intense purple umbels appear, followed by attractive fruiting umbels. A popular cultivar, 'Globemaster', is shorter (80 centimetres (31 in)) but produces much larger, deep violet, umbels (15–20 centimetres (5.9–7.9 in)). Both varieties have been granted the Royal Horticultural Society's Award of Garden Merit. In nature, the species is found in Iran, Afghanistan, Turkey, Turkmenistan, Tajikistan, and Uzbekistan. In cultivation in the US, it performs well in USDA hardiness zones 6–10. Eating flowers, seeds, leaves, and stems can cause nausea, vomiting, and diarrhea due to the sulfides they contain. Allium is a genus of monocotyledonous flowering plants that includes hundreds of species, including the cultivated onion, garlic, scallion, shallot, leek, and chives. The generic name Allium is the Latin word for garlic, and the type species for the genus is Allium sativum which means "cultivated garlic". Carl Linnaeus first described the genus Allium in 1753. Some sources refer to Greek ἀλέω (aleo, to avoid) by reason of the smell of garlic. Various Allium have been cultivated from the earliest times, and about a dozen species are economically important as crops, or garden vegetables, and an increasing number of species are important as ornamental plants. The decision to include a species in the genus Allium is taxonomically difficult, and species boundaries are unclear. Estimates of the number of species are as low as 260, and as high as 979. Allium species occur in temperate climates of the Northern Hemisphere, except for a few species occurring in Chile (such as A. juncifolium), Brazil (A. sellovianum), and tropical Africa (A. spathaceum). They 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 small (around 2-3 mm in diameter) to rather large (8-10 cm). Some species (such as Welsh onion A. fistulosum and leeks (A. ampeloprasum)) develop thickened leaf-bases rather than forming bulbs as such. Plants of the genus Allium produce chemical compounds, mostly derived from cysteine sulfoxides, that give them a characteristic onion or garlic taste and odor.