The common foxglove plant, digitalis purpurea, is an attractive addition to any garden. Its pink or purple flowers cascade down spikes similar to snapdragons. Most foxglove spikes grow over three feet tall, but some can grow as tall as six feet. However, the Chinese foxglove plant, or rehmannia glutinosa, grows much closer to the ground, with spikes that feature single trumpet-shaped flowers. Regardless of the species, a thick patch of foxglove plants with their colorful flowers can brighten up your garden.
In addition to being a beautiful garden plant, the root of the Chinese foxglove plant is an important herb in Chinese medicine. Actually, this foxglove root is the basis for two different Chinese herbs, depending on how they’re prepared. Fresh Chinese foxglove root is called Sheng Di Huang, which translates to Fresh Earth Yellow, as it is the uncooked (fresh) yellow-colored root that comes from the Earth. Herbalists often shorten the name to simply Sheng Di.
Fresh rehmannia, or Sheng Di, is best known for its ability to clear heat. It’s used when an illness like a cold or the flu doesn’t get better, and instead goes deeper into your body causing a high fever, a very red or scarlet tongue and intense thirst. This kind of heat can also cause spontaneous bleeding or pinpoint bleeding under the skin, called petechiae.
Sheng Di can also be used for a condition called Heart Fire that rises upward, causing sores in your mouth or on your tongue and make your cheeks flush and appear red. In addition, because your Chinese Heart also governs your spiritual and emotional self, this kind of heat can also cause irritability, restlessness and insomnia.
While fresh rehmannia is cooling and is most frequently used to treat heat, it also has the ability to nourish and moisten Yin. That means it can also be used to treat the after effects of heat. In this case, Sheng Di might be added to a formula to help replenish depleted fluids and to treat a dry mouth, constipation, a chronic low-grade fever and many dry skin conditions like eczema.
When rehmannia is cooked in wine, it becomes Shu Di Huang, or Cooked Earth Yellow. Cooking this herb makes it warmer and shifts its actions to one of nourishing and revitalizing. It’s used in formulas to nourish blood, treating symptoms such as dizziness, a pale complexion, and heart palpitations—something similar to certain kinds of anemia. Shu Di is especially useful in women’s reproductive health, too, when blood depletion causes conditions such as irregular periods, light periods, lack of menses and uterine or postpartum bleeding.
Not only does Shu Di Huang tonify your blood, but it also nourishes Yin and Essence related to your Chinese Kidney system. This includes conditions such as low back pain, leg or knee weakness, diabetes, feeling light-headed or dizzy, ringing ears (tinnitus), diminished hearing, and prematurely graying hair. Because Yin is something akin to your body’s nourishing and moistening coolant, when Yin is in short supply, heat can flare up—a condition called deficiency heat, which may take the form of night sweats, a flushed face and the sensation that your bones are hot.
While it sounds like both fresh and cooked rehmannia treat heat and nourish Yin, there’s a difference between the two. Fresh rehmannia, Sheng Di, is better at clearing heat, but can also treat Yin depletion. However, cooked rehmannia, Shu Di is better at treating depleted Yin, Blood and Essence, but can also be used to clear heat related to those deficiencies.
Scientists studying the effects of Chinese foxglove have found that this herb can be effective in treating a variety of conditions, such as high blood pressure, diabetes and fatigue. It was also found to improve bone metabolism for patients with osteoporosis, enhance immunity and have neuro protective properties (protecting nerve cells from degeneration or injury).
Unlike Chinese foxglove, the common foxglove plant, while stately and beautiful, is poisonous. Unfortunately, it is sometimes confused with borage, which is another medicinal plant and sometimes used as a salad green. While gardening or handling the common foxglove plant, it is advised that you wear gloves. These tall, spikey plants contain chemicals called cardiac glycosides, which are used to make the drug digitalis. Digitalis is used to improve both the strength and efficiency of the heart, which helps promote better circulation and controls swelling in the extremities in cardiac patients. If you were to feel the pulse of someone who is taking this drug, it would feel a very strong and powerful!
While it’s interesting that foxglove plants are similar in that they have medicinal properties and both must be prepared in specific ways, the similarities stop there. The common foxglove plant is toxic and Chinese foxglove is not. This underscores the importance of working with a trained, certified and experienced practitioner of Chinese herbal medicine—not only for safety, but also for effective results. If you’d like to know if acupuncture or herbal medicine can help you, please contact me.
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Dr. Jeda Boughton is a Doctor of Traditional Chinese Medicine and Registered Acupuncturist in Vancouver. She is also a Registered Herbologist and the founder of BodaHealth.
