From The Food Encyclopedia by Jacques Rolland and Carol Sherman
The common name of several freely spreading species of the Origanum genus (which also embraces O. majorana or sweet marjoram) used in cooking. Native to the Mediterranean basin, many are hardy to zone 5 and have become a favorite perennial in sunny North American herb gardens since the Second World War (the story goes that soldiers brought back both the herb and an appetite for it). Oregano, particularly O. vulgare cultivars, has a sharp scent and mint-tinged flavor that survives drying, so it's commonly sold, dried and crumbled, alone and in ready-made Italian seasoning mixes, but oregano is also sold fresh in most supermarkets. A must-have herb in many pasta sauce and pizza recipes, oregano leaves are also used to make oil that's touted as a natural health elixir. Lippia graveolens, known as Mexican oregano and a familiar seasoning in Mexican and Tex-Mex cuisine, is indigenous to the American Southwest and Central America where it was used in traditional folk medicines. See also marjoram.
