But although chay (Oldenlandia umbellata
L.) belongs to the Rubiaceae family, like the usual source of "dyer's madder" (Rubia tinctorum L.), it is different from all the others as it contains only one red colorant, alizarin, present in the roots both as the aglycone and in the form of glycosides.
Illustration of Oldenlandia umbellata in Plants of the Coast of Coromandel by William Roxburgh, 1795.
Herbarium sample of Oldenlandia umbellata, Botanical Survey of India, Coimbatore.
Oldenlandia umbellata in the wild, Women's Christian College Campus, Chennai.