Rehmannia, di-huang, Rehmannia glutinosa (Scrophulariaceae, sometimes placed in the Gesneriaceae, and now with new genetic information, placed in the Plantaginaceae-who would have guessed based on morphological features!) is a widely used drug in traditional Chinese medicine (TCM). There are as many varieties of Rehmannia in China as apples in the United States. The brick-red tuberous roots are used in prescriptions related to concepts of blood in TCM paradigms, nourishing yin, cooling the blood, stops bleeding, nourishes the blood, etc. This relative small plant, growing to about 18 inches in height has beautiful, glandular-hairy, reddish, tubular flowers that superficially resemble those of foxglove (Digitalis). There’s lots more on Rehmannia in my book Herbal Emissaries-Bringing Chinese Herbs to the West (with Yue Chongxi).