|Flowers of Rehmannia glutinosa|
Rouy 1909 
Libosch. ex Fisch. & C.A. Mey.
Rehmannia is a genus of six species of flowering plants in the order Lamiales and family Orobanchaceae, endemic to China. It is the only member of the monotypic tribe Rehmannieae. Contrary to the immense majority of the taxa of Orobanchaceae, Rehmannia is not parasitic.
The genus was included in the family Scrophulariaceae or Gesneriaceae in some older classifications. The current placement of the genus is in neither Scrophulariaceae s.s. nor Plantaginaceae s.l. (to which many other former Scrophulariaceae have been transferred). Earlier molecular studies suggested that its closest relatives were the genera Lancea and Mazus, which have been included in Phrymaceae. Subsequently, it was found that Rehmannia groups with Triaenophora, and both taxa are jointly the sister group to Lindenbergia and the parasitic Orobanchaceae. Recently, the latest classification of flowering plants, the APG IV, enlarged Orobanchaceae to include Rehmannia, making it the only other genus, along with Lindenbergia, to not be parasitic within the family.
- Rehmannia chingii
- Rehmannia elata
- Rehmannia glutinosa – (gan) di huang in Chinese (Chinese: (干)地黃)
- Rehmannia henryi
- Rehmannia piasezkii
- Rehmannia solanifolia
Sometimes known as Chinese foxglove due to its superficial resemblance to the genus Digitalis, the species of Rehmannia are perennial herbs. The plants have large flowers and are grown as ornamental garden plants in Europe and North America, and are used medicinally in Asia.
Traditional Chinese medicine
It is the main ingredient in a mixture called si wu tang (four substance decoction) along with Dang gui, Chinese peony (bai shao yao), and Ligusticum striatum (chuan xiong) that is considered a fundamental medicine to support making blood.
When two ingredients, peach (tao ren) and safflower (hong hua), are added, it is called tao hong si wu tang (four substance decoction with peach pit and safflower), which is used in TCM for fatigue.
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- Liu, Chongyun; Tseng, Angela; Yang, Sue (2004). Chinese Herbal Medicine: Modern Applications of Traditional Formulas. CRC Press. pp. 174–175. ISBN 9780203493892.
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