Botany of Onions

• • Onion family, Allium, crops have been cultivated for millennia by people worldwide for sustenance, flavour, and medicinal purposes.

  • Each of these three properties is closely connected to a suite of unique organosulfur compounds present in Allium crops that make them distinct from other wild and cultivated food plants.

  • These compounds impart the characteristic flavours and odours of edible alliums.

  • A substantial body of scientific literature suggests that these organosulfur compounds likely arose through natural selection for pest resistance.

  • In a fortuitous circumstance, humans find these odours and flavours appealing, thus what confers functional significance to the Allium crop for its survival also confers culinary significance to the Allium consumer for gastronomic pleasure.

  • In the allium crops where bulbs are prominent, leaf bases are swollen due to the accumulation of carbohydrates from photosynthesis.

  • In those crops where pseudostems are the edible portion, overlapping leaf bases form a hollow column that has the appearance of a stem, such as the base of the leek.

  • For other allium crops the edible portion is the leaf blade, which also serves as the primary photosynthetic organ. See rampion (Allium tricoccum)

Table 1

• • In addition, at least 18 other Alliums are consumed as a fresh vegetable, pickled, or used as flavouring.

  • The garden (bulb) onion is the most valuable Allium with a total world production of over 30 million metric tons (MT) per year.

  • The world-wide production of garlic is about 10% that of garden onion.

  • Leek and the Japanese bunching onion (scallion) are the next most valuable Alliums with production concentrated in Europe and the Orient, respectively.