Oregano (Origanum vulgare), also called wild majoram, is in the mint family (Lamiaceae). It is used both as a culinary and medicinal plant and is closely related to sweet majoram. Greek oregano is a subspecies, which is also called Italian oegano, and is considered to be the best all-purpose culinary garlic.
From Wikipedia: “Oregano is related to the herb marjoram, sometimes being referred to as wild marjoram. Oregano has purple flowers and spade-shaped, olive-green leaves. It is a perennial, although it is grown as an annual in colder climates, as it often does not survive the winter. Oregano is planted in early spring, the plants being spaced 30 cm (12 in) apart in fairly dry soil, with full sun. ... It prefers a hot, relatively dry climate, but does well in other environments”
“Oregano is an important culinary herb, used for the flavour of its leaves, which can be more flavourful when dried than fresh. It has an aromatic, warm, and slightly bitter taste, which can vary in intensity. Good-quality oregano may be strong enough almost to numb the tongue, but cultivars adapted to colder climates often have a lesser flavor. Factors such as climate, season, and soil composition may affect the aromatic oils present, and this effect may be greater than the differences between the various species of plants. Among the chemical compounds contributing to the flavour are carvacrol, thymol, limonene, pinene, ocimene, and caryophyllene. ...
Oregano's most prominent modern use is as the staple herb of Italian-American cuisine. Its popularity in the U.S. began when soldiers returning from World War II brought back with them a taste for the "pizza herb", which had probably been eaten in southern Italy for centuries. There, it is most frequently used with roasted, fried, or grilled vegetables, meat, and fish. Oregano combines well with spicy foods popular in southern Italy. It is less commonly used in the north of the country, as marjoram generally is preferred.
The dried and ground leaves are most often used in Greece to add flavor to Greek salad, and is usually added to the lemon-olive oil sauce that accompanies fish or meat grills and casseroles.”
Dried oregano as raw food:
If dried correctly, oregano is a raw food. It can be added to a number of raw or cooked dishes.
“Oregano contains essential oils such as thymol, carvacrol, and p-cymene as well as tannins and bitter substances. It also contains 267.2 mg of vitamin C per 100 g of fresh oregano.*”
“Thanks to its high levels of phenols, oregano oil is used in aromatherapy as an effective remedy against bacteria. Since it can irritate the skin, it should only be taken orally and diluted with a carrier oil (e.g., sunflower oil). A single dose is 50 mg (two drops) and can be taken up to ten times daily.
It has been shown that oregano has a positive effect on digestive problems and infectious diseases of the upper respiratory tract. Carvacrol has anti-inflammatory properties.*”
“Many subspecies and strains of oregano have been developed by humans over centuries for their unique flavours or other characteristics. Tastes range from spicy or astringent to more complicated and sweet. Simple oregano sold in garden stores as Origanum vulgare may have a bland taste and larger, less-dense leaves, and is not considered the best for culinary use, with a taste less remarkable and pungent. It can pollinate other more sophisticated strains, but the offspring are rarely better in quality.
The related species, Origanum onites (Greece, Turkey) and O. syriacum (West Asia), have similar flavours. A closely related plant is marjoram from Turkey, which differs significantly in taste though, because phenolic compounds are missing from its essential oil. Some varieties show a flavour intermediate between oregano and marjoram.”
Note (italics): * = Translation from a German Wikipedia entry