In indigenous systems of medicine, Rubia cordifolia Linn. is the accepted source for Manjistha. A recent research found that market samples of R. cordifolia from south India were derived from R. tinctorium. However, R. tinctorium is not a south Indian plant. A plant, which is not found in south India, might not be a source of the adulterant. Polymorphism and geographical variations were reported in R. cordifolia. We concluded that the south Indian sources of R. cordifolia might be derived from a different subspecies or geographical type or plants with different polymorphism and never be from R. tinctorium.
Mitra, S. K. and Kannan, R.
"Rubia cordifolia Linn. (Manjistha) – Controversial Identity,"
Ethnobotanical Leaflets: Vol. 2007
, Article 5.
Available at: http://opensiuc.lib.siu.edu/ebl/vol2007/iss1/5