Barley grass grows to be about three feet tall and is cultivated in temperate regions around the world. Barley has been used as a food source since Neolithic times. Historically, barley was often given as a porridge, and in ancient China, it was used to give the liver a rest because they believed it to be so easily digested. Barley grass is a common ingredient in juice supplements.
Barley - Herbal Encyclopedia, http://www.cloverleaffarmherbs.com/barley/ (accessed March 13, 2017).