Libosch. ex Fisch. & C.A. Mey.
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 (Oxelman et al., 2005), which have been included in Phrymaceae (Beardsley & Olmstead, 2002). Subsequently, it was found (Xie et al., 2009) that Rehmannia and Triaenophora 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.
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 (chuang 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.
Species include: 
- Rehmannia chingii
- Rehmannia elata
- Rehmannia glutinosa - (Gan) Di huang in Chinese (Chinese: (干)地黃)
- Rehmannia henryi
- Rehmannia piasezkii
- Rehmannia solanifolia
- The Angiosperm Phylogeny Group (January 2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181: 1–20. doi:10.1111/boj.12385.
- Jim English (2010). "Traditional Chinese Herbs for Arthritis". Nutrition Review. 5 (2). Archived from the original on 2011-12-10. Retrieved 2011-12-29.
- Liu, Chongyun; Tseng, Angela; Yang, Sue (2004). Chinese Herbal Medicine: Modern Applications of Traditional Formulas. CRC Press. pp. 174–175. ISBN 9780203493892.
- "Rehmannia". The Plant List. Retrieved 7 October 2013.
- Gledhill, David (2008). "The Names of Plants". Cambridge University Press. ISBN 9780521866453 (hardback), ISBN 9780521685535 (paperback). pp 328
|Wikimedia Commons has media related to Rehmannia.|
- Oxelman, B.; Kornhall, P.; Olmstead, R.G.; Bremer, B. 2005. Further disintegration of the Scrophulariaceae. Taxon 54 (2): 411-425.
- Beardsley, P. M. & Olmstead, R. G. 2002. Redefining Phrymaceae: the placement of Mimulus, tribe Mimuleae, and Phryma.American Journal of Botany 89: 1093-1102 (available online)
- Zhi Xia, Yin-Zheng Wang and James F. Smith 2009. Familial placement and relations of Rehmannia and Triaenophora (Scrophulariaceae s.l.) inferred from five gene regions, American Journal of Botany 96: 519-530(available online).
- Flora of China: Rehmannia