Oregano is a perennial herb, growing from 20–80 cm tall, with opposite leaves 1–4 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, 3–4 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]
The ORAC value is expressed in micromoles of Trolox Equivalents per 100 grams of sample (this is the laboratory measure of ORAC).
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