Rhodiola (Rhodiola rosea) is indigenous to the Arctic and Alpine regions of Europe, Asia and America and has long been used as a tonic by many cultures, including the Ancient Greeks. Rhodiola is generally known as an "adaptogen", a term which refers to any agent possessing the ability to increase the body's capacity to adapt to stressful conditions.

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http://en.wikipedia.org/wiki/Rhodiola_rosea