The orange (Citrus x sineinsis -- also known as the sweet orange) is a flowering, evergreen fruit tree originally native to China, but now grown all over the world. The orange is the most commonly grown fruit tree and has an ancient history, dating back to at least 2500 BCE. The fruit of the orange tree (commonly called oranges) is a type of berry called a hesperidium, which typically have a segmented fruit surrounded by a leathery, inedible skin. The skin of the orange is green originally, but turns golden orange when ripe. While oranges will not ripen once picked, ethylene gas is commonly used to force patches of green skin to turn orange.
Most examples of the genus Citrus are infertile, which leads to many hybrid crosses that are commercially grown. These crosses include the bitter orange, the bergamot, the blood orange and the mandarin. Orange trees are typically grafted, usually onto a sour orange rootstock.
Nearly every part of the orange has commercial application. The fruit can be eaten out of hand, juiced, and the peel candied or made into marmalade. The flowers of the bitter orange can be distilled into orange flower water and neroli (a common perfume component), and the green twigs can be steam distilled into another perfume component called petitgrain. The characteristic aroma of oranges is a complex blend of limonene, pinene, and neral and geraniol (both of which are isomers of citral).
Brazil, followed by the United States and India are the three largest growers of oranges and their juice. In the United States, Florida produces 80% of the orange crop.
An orange wheel is a slice of orange meant to fit on the side of a cocktail glass as a garnish. Orange wheels should be cut toward the middle of the orange, so as to maximize fruit and minimize pith, then radially sliced so they sit on the rim of the glass. Using an orange wheel as a garnish forces drinkers to get their nose close to the fruit, which maximizes fresh orange aroma in the cocktail.