Rehmannia


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.

Systematics

Etymology

Rehmannia is named for Joseph Rehmann, a physician 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. 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.

Species list

According to The Plant List, Rehmannia comprises six species.
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 TCM for fatigue.

Chemical constituents

Rehmannia contains the vitamins A, B, C, and D, as well as other compounds, such as catalpol, an iridoid glycoside.