Hedyotis is a very problematic genus or group of genera. Neither the overall identity and limits of this lineage, nor the evolutionary patterns within it, are at all understood or delineated. Widely differing treatments have long been used in different regions and floras. The situation is far from resolution or even general consensus and so many authors treat the genus very broadly[
]. In line with several recent (up to 2013) molecular and phylogenic studies, the Kew ‘World Checklist of Selected Plant Families’ has recognised a number of distinct genera and this is the treatment we are adopting here[
Gerontogea umbellata (L.) Cham. & Schltdl.
Hedyotis brevicalyx Sivar.
Hedyotis indica Roem. & Schult.
Hedyotis linarifolia R.Br. ex Wall.
Hedyotis puberula (G.Don) Arn.
Hedyotis umbellata (L.) Lam.
Hedyotis wightii (Hook.f.) K.K.N.Nair
Oldenlandia puberula G.Don
Oldenlandia wightii Hook.f.
Common Name: Chay Root
Chay root is a small, annual plant.
The plant is gathered from the wild for local use as a medicine and dye. It used to be an important source of a red dye before the large-scale production of synthetic dyes started at the end of the 19th Century[
]. It was commonly gathered from the wild and was also at one time often cultivated as a dye plant[
E. Asia - India, Sri Lanka, Myanmar, Vietnam, Indonesia.
Prefers sandy soils along coasts and river banks, where the roots can penetrate the soil deeply[
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Prefers a well-drained, deep sandy soil[
A decoction of the leaves and bark is considered expectorant and is prescribed in cases of bronchial catarrh, bronchitis, tuberculosis and asthma[
A decoction of the leaves is used as a wash for poisonous bites[
The root is used in the treatment of snake bites[
The root bark, when mixed with alum, is the source of a red dye known as 'Indian Madder' or Chay root'[
]. It is used to stain calico, wool and silk[
]. It was at one time much used for a range of purposes, particularly for dyeing turbans and bandana handkerchiefs[
The root is known for its ability to impart a red colour to wool, silk and calico fabrics. It was much employed for dyeing handkerchiefs in Madras, for which that town was once so famous[
]. Small quantities of the dye have been traded to Europe, but without much success[
The dye consists of a complex mixture of quinones. Some constituents are similar to those found in the dye from Indian madder (Rubia cordifolia), such as alizarin, rubichloric acid and ruberythric acid[
]. Other major constituents of the true Indian madder dye, such as purpurin and purpuroxanthin, are not found in this plant[
]. The dye is considered to be somewhat inferior to the dye of Indian madder, possessing only about half the dyeing power of that species[
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