Parts Most Frequently Used: Root (Dried, Fresh or Prepared)

Flavors/Temps: Sweet, Cold, Slightly Warm

Caution: Considered safe.

History/Folklore: The species name, “glutinosa” comes from glutinous, referring to the sticky nature of the root. It is closely related to another herb that carries the name of the plant family, Scrophularia ningpoensis. Both herbs are commonly used in China, though rehmannia which is stronger, is used far more frequently. Rehmannia is sweet and cold and Scrophularia is bitter and cold. They are similar in their ability to treat conditions that are cold in nature. They often appear together in formulas for this reason.

In China, its name translates as Big Yellow or Yellow Earth. It is often commonly called Chinese Foxglove due to its superficial resemblance to the genus Digitalis.

Rehmannia is famous for treating broken bones and severed or damaged sinews, by expelling blood impediments, replenishing bone marrow, and promoting growth of muscles and flesh.

Its sweet sticky nature is said to help calm and settle Qi, helping to draw it downward so Qi can rise again in its more natural and regular pathways. The large quantities of sugar that are present in rehmannia can overwhelm the digestion giving a person a heavy feeling or slight nausea. Preparations and other herbs that it can be combined with help to counteract this possible effect.

Catalpol, one of the plants main constituents, makes up 3-11% of the undried root (depending on growing conditions) and only 1-2% in the dried root. It appears that cotalpol stimulates the production of adrenal cortical hormones. These hormones have anti-inflammatory properties that make it useful for treating asthma, skin diseases and arthritis. Catalpol is also involved in the production of sex hormones, explaining its use for treating menopause and impotence. New studies are indicating that catalpol may prevent cell death caused by neurodegenerative disorders.

Rehmannia is said to help re-balance Yin in the body. Traditionally it is prepared with yellow wine and black beans. Sheng Di Huang is dried rehmannia root that has been baked till nearly dry then kneaded into small balls. Xian Di Haung is fresh rehmannia newly harvested, and Shu Di Huang is prepared rehmannia, referring to the dried root having been steamed to a black color and then re-dried. Shu Di Huang is often steamed in wine until both the insides and outsides turn black and moist. When the herb is charred it is best for stopping bleeding.