Oregano

Oregano is an important culinary herb, used for the flavor of its leaves, which can be more flavourful when dried than fresh.[7] 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 the cultivars adapted to colder climates often have a lesser flavor. Factors such as climate, seasons 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.

(Ingredient Description Reference: http://en.wikipedia.org/wiki/Oregano)