Salvia officinalis, the common sage or just sage, is a perennial, evergreen subshrub, with woody stems, grayish leaves, and blue to purplish flowers. It is a member of the mint family. It's commonly used in the kitchen to season poultry and add a savory flavor to foods. 
It was used in the Middle Ages to treat fevers, liver disease and epilepsy. In England, the tea drunk as a healthful tonic. It was also believed to strengthen the memory.