Rehmannia
Rehmannia is a genus of seven species of flowering plants in the order Lamiales and family Orobanchaceae, which is native to China and Japan. It has been placed as the only member of the monotypic tribe Rehmannieae, but molecular phylogenetic studies suggest that it forms a clade with Triaenophora. Contrary to the vast majority of the taxa of Orobanchaceae, Rehmannia is not parasitic.
Systematics
Etymology
Rehmannia is named for Joseph Rehmann, a physician who worked in St. Petersburg.Homonymy
The name "Rehmannia" has also been given to a genus of Jurassic ammonites of the family Reineckeidae.Classification
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.. 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. A 2016 classification of flowering plants, the APG IV system enlarged Orobanchaceae to include Rehmannia, making it one of the few genera in the family, along with Lindenbergia, not to be parasitic.Species list
, Plants of the World Online accepted seven species:| Image | Scientific name | Distribution |
| Rehmannia chingii H.L.Li | China | |
| Rehmannia chrysantha M.H.Li & C.H.Zhang | Inner Mongolia | |
| Rehmannia glutinosa DC. | China | |
| Rehmannia henryi N.E.Br. | China | |
| Rehmannia japonica Makino | Japan | |
| Rehmannia piasezkii Maxim. | China | |
| Rehmannia solanifolia P.C.Tsoong & T.L.Chin | China |
Uses
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
Known as dìhuáng or gān dìhuáng in Chinese, R. glutinosa is used as a medicinal herb for many conditions within Chinese traditional formulations.It is the main ingredient in a mixture called si wu tang along with Dang gui, Chinese peony, and Ligusticum striatum that is considered a fundamental medicine to support making blood.
When two ingredients, peach and safflower, are added, it is called tao hong si wu tang, which is used in traditional chinese medicine for fatigue.