The root tuber of Rehmannia glutinosa Libosch. (Fam. Scrophulariaceae).
Mainly in Chinese provinces such as Henan.
Harvest & Processing
Dig out root tubers in autumn; remove rootstocks and rootlets; wash root tubers clean; use while fresh - commonly known as 'Xian dihuang' (Fresh Rehmannia Root). Gently roast Xian dihuang until inside turns black and nearly dry; knead into lumps-commonly known as ' Sheng dihuang' (Raw Rehmannia Root).
Mostly irregular pieces, or oblong and orbicular (round); middle part bulgy, narrower at two ends; 6-12 cm long, 3-6 cm in diameter. Some are small, long and rod-like, slightly flattened and gnarled. Outer surface greyish-black or greyish-brown; extremely wrinkled; lined with irregular transverse curves. Heavy; relatively soft and pliable, does not break easily. When broken, surface brownish-black or pitch-black, lustrous and sticky. Odourless; taste: slightly sweet.
1. Haemoptysis, epistaxis, menorrhagia
2. Menstrual disorders
1. Anaemia, Weakness
2. Nocturnal emission
3. Lowgrade afternoon fever
4. Night sweating
Mainly contains iridoid glycosides such as catalpol and rehmannioside A, B, C, D.
According to C.P., also commonly used is a processed Radix Rehmanniae called ' Shu dihuang' (Prepared Rehmannia Root).
Remark: C.P. = Chinese Pharmacopoeia
The information and images in this Online Herbal Exhibition is form the book, "An Illustrated Chinese Materia Medica in Hong Kong", edited by Professor Zhao Zhongzhen, School of Chinese Medicine, Hong Kong Baptist University. For the complete collection of Chinese Materia Medica compiled by Professor Zhao, please go to this website: http://www.bucmm.org.