Oregano is a perennial herb, growing from 20 to 80 cm tall, with opposite leaves 1 to 4 cm long. Oregano will grow in a pH range between 6.0 (mildly acid) and 9.0 (strongly alkaline) with a preferred range between 6.0 and 8.0. The flowers are purple, 3 to 4 mm long, produced in erect spikes. It is sometimes called wild marjoram, and its close relative O. majorana is known as sweet marjoram.
Oregano is high in antioxidant activity, due to a high content of phenolic acids and flavonoids. It also has shown antimicrobial activity against strains of the food-borne pathogen Listeria monocytogenes. [Source: Wikipedia]
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010