Oregano

Oregano is a perennial, although it is grown as an annual in colder climates, as it often does not survive the winter. It grows to 90 centimetres (35 in) tall and 50 cm (20 in) wide. The leaves are spade-shaped and olive-green. The flowers are purple, pink or white, 4–7 cm (1+1⁄2–2+3⁄4 in) long and grouped in clusters. Oregano is related to the herb marjoram, sometimes being referred to as wild marjoram.

Chemistry. Oregano contains polyphenols, including numerous flavones. The essential oil of oregano is composed primarily of monoterpenoids and monoterpenes, with the relative concentration of each compound varying widely across geographic origin and other factors. Over 60 different compounds have been identified, with the primary ones being carvacrol and thymol ranging to over 80%, while lesser abundant compounds include p-cymene, γ-terpinene, caryophyllene, spathulenol, germacrene D, β-fenchyl alcohol and δ-terpineol. Drying of the plant material affects both quantity and distribution of volatile compounds, with methods using higher heat and longer drying times having greater negative impact. A sample of fresh whole plant material found to contain 33 g/kg dry weight (3.1 g/kg wet) decreased to below a third after warm-air convection drying. Much higher concentrations of volatile compounds are achieved towards the end of the growing season.

Oregano is a culinary herb, used for the flavour of its leaves, which can be more intense when dried than fresh. It has an earthy, warm, and slightly bitter taste, which can vary in intensity. Good-quality oregano may be strong enough to almost numb the tongue, but cultivars adapted to colder climates may have a lesser flavour. 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 is the staple herb of Italian cuisine, 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, where marjoram is preferred. It became popular in the U.S. after soldiers returning from World War II brought back a taste for the "pizza herb", which had probably been eaten in Southern Italy for centuries. Oregano is widely used in cuisines of the Mediterranean Basin and Latin America, especially in Mexican cuisine and Argentine cuisine. In Turkish cuisine, oregano is mostly used for flavouring meat, especially mutton and lamb. …

Oregano is planted in early spring, the plants being spaced 30 cm (12 in) apart in fairly dry soil, with full sun. It will grow in a pH range between 6.0 (mildly acidic) and 9.0 (strongly alkaline), with a preferred range between 6.0 and 8.0. It prefers a hot, relatively dry climate, but does well in other environments.

The English word "oregano" is a borrowing of the Spanish orégano, which derives from the Latin orīganum, which itself comes from Classical Greek ὀρίγανον (orī́ganon). The ultimate origin is disputed; some claim it is a compound Greek term that consists of ὄρος (óros) meaning "mountain", and γάνος (gános) meaning "joy" while The Oxford English Dictionary states it is "probably a loanword [as] the plant comes from Africa".